Human anatomy and physiology sapin. Anatomy and physiology of a person with age-related characteristics of a child's body - Sapin M.R.

TEACHER EDUCATION

M. R. SAPIN, V. I. SIVOGLAZOV

ANATOMY

AND HUMAN PHYSIOLOGY

(WITH AGE CHARACTERISTICS OF CHILDREN'S ORGANISM)

Ministry of Education of the Russian Federation as a teaching aid for students of secondary pedagogical educational institutions

3rd edition stereotypical

UDC611/612(075.32) BBK28.86ya722

Publishing program "Textbooks and teaching aids for teacher training schools and colleges"

Program Manager Z.A. Nefedova

R e e n s e n t s:

head Department of Anatomy and Sports Morphology of the Academy of Physical Culture, Corresponding Member of the Russian Academy of Medical Sciences,

Professor B.A. Nikityuk;

head Head of the Department of Human Anatomy of the Moscow Medical Dental Institute, Doctor of Medical Sciences, Professor L. L. Kolesnikov

Sapin M.R., Sivoglazov V.I.

C19 Human anatomy and physiology (with age-related characteristics of the child's body): Proc. allowance for students. avg. ped. textbook establishments. - 3rd ed., stereotype. - M.: Publishing Center "Academy", 2002. - 448 p., 8 p. ill.: ill.

ISBN 5-7695-0904-X

The manual provides basic information on human anatomy and physiology from the standpoint of modern medical science. The age-related changes that occur in the child's body are especially highlighted.

The book is written in an accessible form. The texts are provided with drawings, charts, tables, which facilitate easy assimilation of the material.

Students of pedagogical universities can also use the textbook.

UDC 611/612(075.32) BBK28.86ya722

INTRODUCTION

Anatomy and physiology are the most important sciences about the structure and functions of the human body. Every physician, every biologist should know how a person works, how his organs “work”, especially since anatomy and Physiology belongs to the biological sciences.

Man, as a representative of the animal world, obeys the biological laws inherent in all living beings. At the same time, man differs from animals not only in his structure. He is distinguished by developed thinking, intellect, the presence of articulate speech, social conditions of life and social relationships. Labor and the social environment have had a great influence on the biological characteristics of a person and have significantly changed them.

Knowledge of the features of the structure and functions of the human body is useful to any person, especially since sometimes, under unforeseen circumstances, there may be a need to help the victim: stop the bleeding, make artificial respiration. Knowledge of anatomy and physiology makes it possible to develop hygiene standards necessary in everyday life and at work to maintain human health.

human anatomy(from Greek. anatome- dissection, dismemberment) is the science of forms and structure, origin and development of the human body, its systems and organs. Anatomy studies the external forms of the human body, its organs, their microscopic and ultramicroscopic structure. Anatomy studies the human body at various periods of life, from the origin and formation of organs and systems in the embryo and fetus to old age, studies a person under the influence of the external environment.

Physiology(from Greek. physis- nature, logos- science) studies the functions, life processes of the entire or-

ganism, its organs, cells, relationships and interactions in the human body in different age periods and in a changing environment.

Much attention in anatomy and physiology is paid to childhood, during the period of rapid growth and development of the human body, as well as to the elderly and senile age, when involutive processes are manifested, often contributing to various diseases.

Knowledge of the basics of anatomy and physiology allows not only to understand oneself. Detailed knowledge of these subjects forms the biological and medical thinking of specialists, makes it possible to understand the mechanisms of processes occurring in the body, to study the relationship of a person with the external environment, the origin of body types, anomalies and malformations.

Anatomy studies the structure, and physiology - the functions of a practically healthy, "normal" person. At the same time, among the medical sciences there are pathological anatomy and pathological physiology (from the Greek. pathia- disease, suffering), which examine organs altered by diseases and physiological processes disturbed in this case.

Normal can be considered such a structure of the human body, its organs, when their functions are not impaired. However, there is a concept of individual variability (variants of the norm), when body weight, height, physique, metabolic rate deviate in one direction or another from the most common indicators. Strongly pronounced deviations from the normal structure are called anomalies (from the Greek. anomaly- irregularity, abnormality). If an anomaly has an external manifestation that distorts the appearance of a person, then they speak of malformations, deformities, the origin and structure of which is studied by the science of teratology (from the Greek. teras- freak). Anatomy and physiology are constantly updated with new scientific facts, new patterns are revealed. The progress of these sciences is associated with the improvement of research methods, the widespread use of the electron microscope, scientific achievements in the field of molecular

polar biology, biophysics, genetics, biochemistry.

Human anatomy, in turn, serves as the basis for a number of other biological sciences. This is anthropology (from the Greek. anthropos- man) - the science of man, his origin, human races, their distribution over the territory

riyam of the earth; histology (from the Greek. histos- tissue) - the doctrine of the tissues of the human body, from which organs are built; cytology (from the Greek. kitus- cell) - the science of the structure and vital activity of various types of cells; embryology (from the Greek. embryonic- embryo) - a science that studies the development of a person (and animals) in the prenatal period of life, education, formation of individual organs and the body as a whole. All these sciences are part of the general doctrine of man. However, having appeared in the depths of anatomy, they separated from it at different times due to the emergence of new research methods and the development of new scientific directions.

Plastic anatomy contributes to the study of a person, his external forms and proportions of his body. X-ray anatomy, due to the penetrating ability of X-rays, examines the structure and position of the bones of the skeleton and other organs with different tissue densities. Endoscopy method (from the Greek. endo- inside, scopia- at the end of the word - research with mirrors) makes it possible to examine hollow internals from the inside with the help of tubes and optical systems. Anatomy and physiology use various experimental methods, which makes it possible to investigate and understand the mechanisms of changes and adaptive processes in organs and tissues, to study reserve possibilities their livelihoods.

Anatomy and physiology study the structure and functions of the human body in parts, first - its individual organs, systems and apparatuses of organs. Analyzing the results obtained, anatomy and physiology ultimately study the integral human organism.

MAIN STAGES OF HUMAN DEVELOPMENT

Each person has his own individual characteristics, the presence of which is determined by two factors. This is heredity - traits inherited from parents, as well as the result of the influence of the external environment in which a person grows, develops, studies, works.

Individual development, or development in ontogenesis, occurs in all periods of life - from conception to death. In human ontogenesis (from the Greek. on, genus. case ontos- existing) distinguish two periods: before birth (intrauterine) and after birth (extrauterine). In the intrauterine period, from conception to birth, the embryo (embryo) develops in the mother's body. During the first 8

weeks, the main processes of formation of organs and parts of the body take place. This period is called the embryonic period, and the organism of the future person is called an embryo (embryo). Starting from the 9th week of development, when the main external human features have already begun to be identified, the organism is called a fetus, and the period is called fetal.

After fertilization(fusion of sperm and egg), which usually occurs in the fallopian tube, a unicellular embryo is formed - a zygote. Within 3-4 days, the zygote is crushed (divided). As a result, a multicellular vesicle is formed - a blastula with a cavity inside. The walls of this vesicle are formed by two types of cells: large and small. From small cells, the walls of the vesicle are formed - the trophoblast, from which the outer layer of the shells of the embryo is subsequently created. Larger cells (blastomeres) form clusters - embryoblast (embryo rudiment), which is located inside the trophoblast (Fig. 1). The embryo and adjacent extraembryonic structures (except for the trophoblast) develop from this accumulation (“nodule”). The embryo, which looks like a ka, on the 6-7th day of pregnancy is introduced (implanted) into the uterine mucosa. In the second week of development, the embryo (embryoblast) is divided into two plates.

Rice. 1. The position of the embryo and embryonic membranes at different stages of human development:

A - 2-3 weeks; B - 4 weeks; 1 - amnion cavity, 2 - body of the embryo, 3 - yolk sac, 4 - trophoblast; B - 6 weeks; D - fetus 4-5 months: 1 - body of the embryo (fetus), 2 - amnion, 3 - yolk sac, 4 - chorion, 5 - umbilical cord

ki. One plate adjacent to the trophoblast is called the outer germ layer (ectoderm). The inner plate, facing the cavity of the vesicle, makes up the inner germ layer (endoderm). The edges of the inner germ layer grow to the sides, bend and form a vitelline vesicle. The outer germ layer (ectoderm) forms the amniotic vesicle. In the cavity of the trophoblast around the vitelline and amniotic vesicles, cells of the extraembryonic mesoderm, the embryonic connective tissue, are loosely located. At the point of contact between the vitelline and amniotic vesicles, a two-layer plate is formed - the germinal shield. The plate that belongs

to the amniotic vesicle, forms the outer part of the germinal shield (ectoderm). The plate of the germinal shield, which is adjacent to the yolk vesicle, is the germinal (intestinal) endoderm. From it develop the epithelial cover of the mucous membrane of the digestive organs (digestive tract) and respiratory tract, as well as the digestive and some other glands, including the liver and pancreas.

The trophoblast, together with the extraembryonic mesoderm, form the villous membrane of the embryo - the chorion, which participates in the formation of the placenta ("children's place"), through which the embryo receives nutrition from the mother's body.

On the 3rd week of pregnancy (from the 15th-17th day of embryogenesis), the embryo acquires a three-layer structure, its axial organs develop. The cells of the outer (ectodermal) plate of the germinal shield are displaced towards its posterior end. As a result, a thickening is formed near the ectodermal plate - a primary strip oriented anteriorly. The anterior (cranial) part of the primary strip has a slight elevation - the primary (Hensen's) nodule. The cells of the outer nodule (ectoderm), lying in front of the primary vesicle, plunge into the gap between the outer (ectodermal) and inner (endodermal) plates and form the chordal (head) process, from which the dorsal string is formed - the chord. The cells of the primary streak, growing in both directions between the outer and inner plates of the germinal shield and on the sides of the notochord, form the middle germinal layer - the mesoderm. The embryo becomes three-layered. At the 3rd week of development, the neural tube begins to form from the ectoderm.

The allantois protrudes from the back of the endodermal plate into the extraembryonic mesoderm (the so-called amniotic stalk). In the course of the allantois from the embryo through the amniotic stalk to the chorion villi, blood (umbilical) vessels also sprout, which later form the basis of the umbilical cord.

At the 3-4th week of development, the body of the embryo (embryonic shield) gradually separates from extraembryonic organs (yolk sac, allantois, amniotic stalk). The embryonic shield is bent, a deep furrow is formed on its sides - the trunk fold. This fold delimits the edges of the germ layer from the amniotic

she is. The body of the embryo from a flat shield turns into a three-dimensional one, the ectoderm covers the embryo from all sides.

The endoderm, which is inside the body of the embryo, rolls up into a tube and forms the rudiment of the future intestine. The narrow opening connecting the embryonic intestine with the yolk sac later turns into the umbilical ring. From the endoderm, the epithelium and glands of the gastrointestinal tract and respiratory tract are formed. From the ectoderm, the nervous system, the epidermis of the skin and its derivatives, the epithelial lining of the oral cavity, the anal part of the rectum, the vagina and other organs are formed.

The embryonic (primary) intestine is initially closed in front and behind. In the anterior and posterior ends of the body of the embryo, invaginations of the ectoderm appear - the oral fossa (future oral cavity) and the anal (anal) fossa. There is a two-layer (ectoderm and endoderm) anterior (pharyngeal) membrane in front between the cavity of the primary intestine and the oral fossa. Between the intestine and the anal fossa there is an anal membrane, also two-layered. The anterior (pharyngeal) membrane breaks through at 3-4 weeks of development. At the 3rd month, the posterior (anal) membrane breaks. The amnion, filled with amniotic fluid, surrounds the embryo, protecting it from various injuries and concussions. The growth of the yolk sac gradually slows down, and it is reduced.

At the end of the 3rd week of development, mesoderm differentiation begins. The mesenchyme arises from the mesoderm. The dorsal part of the mesoderm, located on the sides of the chord, is subdivided into 43-44 pairs of body segments - somites. Three parts are distinguished in somites. The anteromedial is the sclerotome, from which the bones and cartilages of the skeleton develop. Lateral to the sclerotome is the myotome, from which the striated skeletal muscles are formed. Outside lies the dermatome, from which the skin itself arises.

pleural and pericardial cavities. From the mesenchyme of the ventral non-segmented mesoderm (splanchnotome), unstriated smooth muscle tissue, connective tissue, blood and lymphatic vessels, and blood cells are formed. The heart, kidneys, adrenal cortex, gonads, and other structures also develop from the mesenchyme of splanchnotomes.

By the end of the first month of intrauterine development, the laying of the main organs of the embryo, which has a length of 6.5 mm, ends.

On the 5th-8th week, the fin-like rudiments of the upper and then the lower extremities appear in the embryo in the form of skin folds, into which the anlagen of bones, muscles, vessels and nerves later grow.

On the 6th week, the laying of the outer ear appears, on the 6-7th week, the fingers begin to form, and then the toes. On the 8th week, the laying of organs ends. Starting from the 3rd month of development, the embryo takes on the appearance of a person and is called a fetus. On the 10th month, the fetus is born.

During the entire fetal period, there is a growth and further development of already formed organs and tissues. The differentiation of the external genitalia begins. Nails are laid on the fingers. At the end of the 5th month, eyebrows and eyelashes appear. At the 7th month, the eyelids open, fat begins to accumulate in the subcutaneous tissue. After birth, the child grows rapidly, the weight and length of his body, and the surface area of the body increase (Table 1). Human growth continues during the first 20 years of his life. In men, the increase in body length ends, as a rule, at 20-22 years old, in women - at 18-20 years old. Then, up to 60-65 years, the body length almost does not change. However, in the elderly and senile age (after 60-70 years), due to an increase in the bends of the spinal column and a change in body posture, thinning of the intervertebral discs, flattening of the arches of the foot, the body length decreases by 1-1.5 mm annually.

During the first year of life after birth, the height of the child increases by 21-25 cm.

During the periods of early and first childhood (1 year - 7 years) the growth rate decreases rapidly, at the beginning of the period of the second childhood (8-12 years) the growth rate is 4.5-5.5 cm per year, and then increases. In adolescence (12-16 years), the annual increase in body length for boys is on average 5.8 cm, for girls - about 5.7 cm.

Length, body weight and body surface area in different age periods of postnatal ontogenesis

Indicators	Newborn	Age periods / gender (m-male, w-female)
8 years	10 years	12 years	14 years old
	m f	m f	m f	m f	m f
Body length, cm	50,8 55,0	126,3 126,4	136,3 137,3	143,9 147,8	157,0 157,3
Body weight, kg	3,5 3,4	26,1 25,6	32,9 31,8	35,8 38,5	46,1 49,1
Surface area	2200 2200
body weight, cm2
Indicators	Age periods
	16 years	18 years	20 years	22		24-60 years old
	m f	m f	m f	m f	m f	m f
Body length, cm	169,8 160,2	161,8	173,6 162,8	174,7 162,7	174,7 162,8	174,5 162,6
Body weight, kg	59,1 56,8	67,6	70,2 57,1	57,3	71,9 57,5	71,7 56,7
Surface area						18000 16000
body weight, cm2

Note: figures are taken from the books “Man. Morphobiological Data” (1977), “Human Morphology”, ed. Nikityuk, Chtetsova (1990).

At the same time, in girls, the most intensive growth is observed at the age of 10 to 13 years, and in boys - in adolescence. Then growth slows down.

Body weight doubles by 5-6 months after birth. Body weight triples by one year and increases by about 4 times by two years. The increase in body length and weight is approximately the same speed. The maximum annual increase in body weight is observed in adolescents: in girls at the 13th, and in boys - at the 15th year of life. Body weight increases up to 20-25 years, and then stabilizes. Stable body weight usually persists until 40-46 years. It is considered important and physiologically justified to maintain body weight until the end of life within the figures of 19-20 years of age.

Over the past 100-150 years, there has been an acceleration of morphofunctional development and maturation of the whole organism in children and adolescents (acceleration), which is more pronounced in economically developed countries. Thus, the body weight of newborns increased by an average of 100-300 g over a century, and that of one-year-olds by 1500-2000 g. The body length also increased by 5 cm. The body length of children during the second childhood and in adolescents increased by 10-15 cm, and in adult men - by 6-8 cm. The time during which the length of the human body increases has decreased. At the end of the 19th century, growth continued up to 23-26 years. At the end of the 20th century, in men, the growth of the body in length occurs up to 20-22 years, and in women up to 18-20 years. Accelerated eruption of milk and permanent teeth. Faster mental development, puberty. At the end of the 20th century, compared with its beginning, the average age of menstruation in girls decreased from 16.5 to 12-13 years, and the time of menopause increased from 43-45 to 48-50 years.

After birth, during the period of continuing human growth, each age has its own morphological and functional features.

A newborn child has a round, large head, a short neck and chest, a long belly, short legs, and long arms (Fig. 2). The circumference of the head is 1-2 cm larger than the circumference of the chest, the cerebral part of the skull is relatively larger than the facial part. The shape of the chest is barrel-shaped. The spine is devoid of curves, the promontory is only slightly pronounced. The bones that form the pelvic bone are not fused together. The internal organs are relatively larger than those of an adult. For example, the mass of the liver

Rice. 2. Changes in the proportions of body parts in the process of growth.

newborn baby is "/20 body weight, while at an adult - "/ 50. The length of the intestine is 2 times the length of the body, at an adult - 4-4.5 times. The mass of the brain of a newborn is 13-14% of body weight, and at only about 2% of an adult. The adrenal glands and thymus are large.

In infancy (10 days - 1 year) the child's body grows most rapidly. From about 6 months, the eruption of milk teeth begins. During the first year of life, the sizes of a number of organs and systems reach the sizes characteristic of an adult (eye, inner ear, central nervous system). During the first years of life, the musculoskeletal system, digestive and respiratory systems rapidly grow and develop.

During early childhood (1-3 years) all milk teeth erupt and the first “rounding” occurs, i.e. the increase in body weight outstrips the growth of the body in length. The mental development of the child, speech, memory is rapidly progressing. The child begins to navigate in space. During the 2nd-3rd years of life, the growth in length prevails over the increase in body weight. At the end of the period, the eruption of permanent teeth begins. In connection with the rapid development of the brain, the mass of which by the end of the period already reaches 1100-

1200 g, mental abilities develop rapidly, visual thinking, the ability to recognize for a long time, orientation in time, in the days of the week.

In early childhood(4-7 years old) gender differences (except for primary sexual characteristics) are almost not expressed,

During the second childhood(8-12 years old) growth in width again prevails, however, at this time puberty begins, and by the end of the period, body growth in length intensifies, the rate of which is greater in girls.

The mental development of children is progressing. Orientation towards months and calendar days develops. Puberty begins, earlier in girls, which is associated with increased secretion of female sex hormones. In girls, at 8-9 years old, the pelvis begins to expand and the hips become rounded, the secretion of the sebaceous glands increases, pubic hair grows. The boys in 10-11 years of age, the growth of the larynx, testicles and penis begins, which by the age of 12 increases by 0.5-0.7 cm.

AT adolescence(12-16 years old) growing fast and sexual organs develop, secondary sexual characteristics intensify. In girls, the amount of hair on the skin of the pubic area increases, hair appears in the armpits, the size of the genital organs and mammary glands increase, the alkaline reaction of the vaginal secretion becomes acidic, menstruation appears, and the size of the pelvis increases. In boys, the testicles and penis rapidly increase, at first the pubic hair develops according to the female type, the mammary glands swell. By the end of adolescence (15-16 years), hair growth begins on the face, body, in the armpits, and on the pubis - according to the male type, the skin of the scrotum becomes pigmented, the genitals increase even more, the first ejaculations occur (involuntary ejaculations).

In adolescence, mechanical and verbal-logical memory develops.

Youth age (16-21 year) coincides with the period of maturation. At this age, the growth and development of the body in basically ends, all apparatuses and organ systems practically reach morphofunctional maturity.

body structure in adulthood(22-60 years old) changes little, and in the elderly(61-74 years old) and senile(75-90 years old) there are restructurings characteristic of these ages, which are studied by a special science - gerontology (from the Greek .geron- old man). Temporary boundaries

rhenium varies widely in different individuals. In old age, there is a decrease in the adaptive capabilities of the body, a change in the morphofunctional parameters of all apparatuses and organ systems, among which the most important role belongs to the immune, nervous and circulatory systems.

An active lifestyle and regular physical activity slow down the aging process. However, this is possible within the limits due to hereditary factors.

A man is distinguished from a woman by sexual characteristics (Table 2). They are divided into primary (genital organs) and secondary (development of pubic hair, development of mammary glands, voice changes, etc.).

table 2

Some gender differences between men (m) and women(g)

Indicators	Floor
m	well
Body length	More	Smaller
Body mass	More	Smaller
Trunk (relative	Briefly speaking	Longer
dimensions)
limbs {%%)	Longer	Briefly speaking
Shoulders	Shire	Already
Taz	Already	Shire
Rib cage	Longer, wider	In short, already
Stomach	Briefly speaking	Longer
Muscle mass	More	Smaller
subcutaneous adipose	Smaller	More
cellulose
Leather	thicker	Thinner
Hair	More on the face	Less than
	body, end	abdomen is absent
	nostalgia, plentiful	there are
	on the forehead and abdomen
	to the navel

body structures are approaching the average values of the norm (taking into account age, gender). faces brachymorphic(from Greek. brachys- short) body types (hypersthenics) are short in stature, have a wide body, and tend to be overweight. Their diaphragm is located high, the heart lies on it almost transversely, the lungs are short, the muscles are well developed. Persons dolichomorphic body type (from the Greek. dolichos- long) high stature, long limbs. The muscles are poorly developed. The diaphragm is low, the lungs are long, the heart is located almost vertically.

Human anatomy studies the structure of a normal (averaged) person, therefore such anatomy is called normal. For the convenience of studying the position of organs and parts of the body, three mutually perpendicular planes are used. Sagittal plane(from Greek. sagitta- arrow) vertically cuts the body from front to back. Frontal plane(from lat. from- forehead) is located perpendicular to the sagittal, oriented from right to left. horizontal plane occupies a perpendicular position with respect to the first two, it separates the upper part of the body from the lower.

A large number of such planes can be drawn through the human body. The sagittal plane separating the right half of the body from the left is called the median plane. The frontal plane separates the front of the body from the back.

In anatomy, terms are distinguished average(medial, lying closer to the median plane) and side(lateral, located at a distance from the median plane). To designate parts of the upper and lower extremities, the concepts proximal- located closer to the beginning of the limb, and distal- located farther from the body.

When studying anatomy, terms such as right and left, large and small, superficial and deep are used.

When determining the position of organs in a living person, the projections of their boundaries on the surface of the body use vertical lines drawn through certain points. Anterior median line is carried out in the middle of the front surface of the body. Posterior median line runs along the spinous processes of the vertebrae. Both of these lines connect the right half of the body with the left. Right and left

sternal (oblosternal) lines run along the corresponding edges of the sternum. midclavicular line runs vertically through the middle of the clavicle. Axillary (anterior, middle and posterior) lines are drawn through the middle and the corresponding edges of the axillary fossa. The scapular line passes through the lower angle of the scapula. Paravertebral line is carried out next to the spine through the costotransverse joints.

Questions for repetition and self-control:

1. What is a zygote? What and where is it formed from?

2. What embryonic structures form the ectoderm and endoderm? Which organs of them develop in the future?

3. When and from what is the middle germ layer formed?

4. What parts are isolated from somites and from splanchnotome?

5. What factors influence the development of the embryo?

6. What anatomical features are typical for a newborn?

7. What systems and apparatuses of organs grow and develop faster in children, adolescents, in adolescence?

8. Name the body types you know and their distinctive features.

STRUCTURE OF THE HUMAN BODY

The human body, which is a single, integral, complex system, consists of organs and tissues. Organs that are built from tissues are combined into systems and apparatuses. Tissues, in turn, consist of various types of cells and intercellular substance.

Cell is an elementary, universal unit of living matter. The cell has an ordered structure, is able to receive energy from outside and use it to perform the functions inherent in each cell. Cells actively respond to external influences (irritations), participate in metabolism, have the ability to grow, regenerate, reproduce, transfer genetic information, and adapt to environmental conditions.

Cells in the human body are diverse in shape, they can be flat, round, ovoid, spindle-

shaped, cubic, process. The shape of cells is determined by their position in the body and function. Cell sizes vary from a few micrometers (eg, a small lymphocyte) to 200 microns (an ovum).

The intercellular substance is a product of cell vital activity and consists of the main substance and various connective tissue fibers located in it.

Despite the great diversity, all cells have common structural features and consist of a nucleus and cytoplasm enclosed in a cell membrane - the cytolemma (Fig. 3). The cell membrane, or cell membrane (lemma, plasmalemma), delimits the cell from the external environment. The thickness of the cytolemma is 9-10 nm (1 nanometer is equal to m or 0.002 microns). The cytolemma is built from protein and lipid molecules and is a three-layer structure, the outer surface of which is covered with fine fibrillar glycocalyx. The glycocalyx contains various carbohydrates that form long branching chains of polysaccharides. These polysaccharides are associated with protein molecules that are part of the cytolemma. In the cytolemma, the outer and inner electron-dense lipid layers (lamellae) are about 2.5 nm thick, and the middle electron-transparent layer (hydrophobic zone of lipid molecules) is about 3 nm thick. The bilipid layer of the cytolemma contains protein molecules, some of which pass through the entire thickness of the cell membrane.

The cytolemma not only separates the cell from the external environment. It protects the cell, performs receptor functions (perceives the effects of the external environment for the cell), and a transport function. Various substances (water, low molecular weight compounds, ions) are transferred through the cytolemma both inside the cell and out of the cell. When energy is consumed (ATP splitting), various organic substances (amino acids, sugars, etc.) are actively transported through the cytolemma.

Rice. 3. Scheme of the ultramicroscopic structure of the cell: 1 - cytolemma (plasma membrane), 2 - pinocytic vesicles, 3 - centrosome (cell center, cytocenter), 4 - hyaloplasm, 5 - endoplasmic reticulum (a - membranes of the endoplasmic reticulum, b - ribosomes), 6 - nucleus, 7 - connection of the perinuclear space with the cavities of the endoplasmic reticulum, 8 - nuclear pores, 9 - nucleolus, 10 - intracellular reticular apparatus (Golgi complex), 11 - secretory vacuoles, 12 - mitochondria, 13 - lysosomes, 14 - three successive stages of phagocytosis, 15 - connection of the cell membrane (cytolemma) with the membranes of the endoplasmic reticulum

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PEDAGOGICAL EDUCATION M.R. SAPIN, V.I.

as a textbook for students of secondary pedagogical educational institutions 3rd edition, stereotypical Moscow ACADEMA 2002 UDC611/612(075.32) BBK28.86ya722 19 Publishing program "Textbooks and teaching aids for pedagogical schools and colleges" Head of the program Z.A. Nefedova Rece n e nt s:

head Department of Anatomy and Sports Morphology of the Academy of Physical Culture, Corresponding Member of the Russian Academy of Medical Sciences, Professor B.A. Nikityuk;

head Department of Human Anatomy of the Moscow Medical Dental Institute, Doctor of Medical Sciences, Professor L. L. Kolesnikov Sapin M.R., Sivoglazov V.I.

C19 Human anatomy and physiology (with age-related characteristics of the child's body): Proc. allowance for students. avg. ped. textbook establishments. - 3rd ed., stereotype. - M.: Publishing Center "Academy", 2002. - 448 p., 8 p. ill.: ill.

ISBN 5-7695-0904-X The manual provides basic information on human anatomy and physiology from the standpoint of modern medical science.

The age-related changes that occur in the child's body are especially highlighted.

The book is written in an accessible form. The texts are provided with pictures, diagrams, tables, which facilitate easy assimilation of the material.

Students of pedagogical universities can also use the textbook.

UDC 611/612(075.32) BBK28.86ya © Sapin M.R., Sivoglazov V.I., ISBN 5-7695-0904-X © Publishing Center "Academy", INTRODUCTION Anatomy and physiology are the most important sciences about the structure and functions of the human body. Every physician, every biologist should know how a person works, how his organs “work”, especially since both anatomy and physiology are biological sciences.

Knowledge of the features of the structure and functions of the human body is useful to any person, especially since sometimes, under unforeseen circumstances, there may be a need to help the victim: stop bleeding, make artificial respiration. Knowledge of anatomy and physiology makes it possible to develop hygiene standards necessary in everyday life and at work to maintain human health.

Human anatomy (from the Greek anatome - dissection, dissection) is the science of the forms and structure, origin and development of the human body, its systems and organs. Anatomy studies the external forms of the human body, its organs, their microscopic and ultramicroscopic structure. Anatomy studies the human body at various periods of life, from the origin and formation of organs and systems in the embryo and fetus to old age, studies a person under the influence of the external environment.

Physiology (from the Greek physis - nature, logos - science) studies the functions, life processes of the whole organism, its organs, cells, relationships and interactions in the human body at different age periods and in a changing environment.

Knowledge of the basics of anatomy and physiology allows not only to understand oneself. Detailed knowledge of these subjects forms the biological and medical thinking of specialists, makes it possible to understand the mechanisms of the processes occurring in the body, to study the relationship of a person with the external environment, the origin of body types, anomalies and malformations.

Anatomy studies the structure, and physiology - the functions of a practically healthy, "normal" person. At the same time, among the medical sciences there are pathological anatomy and pathological physiology (from the Greek pathia - disease, suffering), which explore organs altered by diseases and physiological processes disturbed.

Strongly pronounced deviations from the normal structure are called anomalies (from the Greek anomalia - irregularity, abnormality). If an anomaly has an external manifestation that distorts the appearance of a person, then they speak of malformations, deformities, the origin and structure of which is studied by the science of teratology (from the Greek teras - freak).

Anatomy and physiology are constantly updated with new scientific facts, reveal new patterns.

The progress of these sciences is associated with the improvement of research methods, the widespread use of the electron microscope, and scientific achievements in the field of molecular biology, biophysics, genetics, and biochemistry.

histology (from the Greek histos - tissue) - the study of the tissues of the human body from which organs are built;

cytology (from the Greek kytus - cell) - the science of the structure and vital activity of various types of cells;

embryology (from the Greek embryon - embryo) is a science that studies the development of a person (and animals) in the prenatal period of life, the formation, formation of individual organs and the body as a whole. All these sciences are part of the general doctrine of man. However, having appeared in the depths of anatomy, they separated from it at different times due to the emergence of new methods of research, the development of new scientific directions.

The method of endoscopy (from the Greek endo - inside, scopia - at the end of the word - examination with mirrors) makes it possible, using tubes and optical systems, to examine hollow internals from the inside. Anatomy and physiology use various experimental methods, which makes it possible to investigate and understand the mechanisms of changes and adaptive processes in organs and tissues, to study the reserve possibilities of their vital activity.

MAIN STAGES OF HUMAN DEVELOPMENT Each person has his own individual characteristics, the presence of which is determined by two factors. This is heredity - traits inherited from parents, as well as the result of the influence of the external environment in which a person grows, develops, learns, works.

Individual development, or development in ontogenesis, occurs in all periods of life - from conception to death.

In human ontogenesis (from the Greek on, genus case ontos - existing) there are two periods: before birth (intrauterine) and after birth (extrauterine). In the intrauterine period, from conception to birth, the embryo (embryo) develops in the mother's body. During the first weeks, the main processes of formation of organs and parts of the body take place. This period is called embryonic, and the organism of the future person is an embryo (embryo). Starting from the 9th week of development, when the main external human features have already begun to be identified, the organism is called a fetus, and the period is fetal.

After fertilization (the fusion of the spermatozoon and the egg of the cell), which usually occurs in the fallopian tube, a unicellular embryo is formed - the zygote. Within 3 days, the zygote splits (divides). As a result, a multicellular vesicle is formed - a blastula with a cavity inside.

The walls of this vesicle are formed by two types of cells:

large and small. Small cells form the walls of the vesicle - the trophoblast, from which the outer layer of the shells of the embryo is subsequently created. Larger cells (blastomeres) form clusters - embryoblast (embryo bud), which is located inside the trophoblast (Fig. 1). The embryo and adjacent extraembryonic structures (except for the trophoblast) develop from this accumulation (“nodule”). The embryo, which looks like a ka, on the 6-7th day of pregnancy is introduced (implanted) into the uterine mucosa. In the second week of development, the embryo (embryoblast) is divided into two plates (Fig. 1. The position of the embryo and embryonic membranes at different stages of human development:

A - 2-3 weeks;

1 - amnion cavity, 2 - body of the embryo, 3 - yolk sac, 4 - trophoblast;

D - fetus 4-5 months:

1 - body of the embryo (fetus), 2 - amnion, 3 - yolk sac, 4 - chorion, 5 - umbilical cord. One plate adjacent to the trophoblast is called the outer germ layer (ectoderm).

The inner plate, facing the cavity of the vesicle, makes up the inner germ layer (endoderm).

The edges of the inner germ layer expand to the sides, bend and form a yolk vesicle. The outer germ layer (ectoderm) forms the amniotic vesicle. In the cavity of the trophoblast around the vitelline and amniotic vesicles, cells of the extraembryonic mesoderm, the embryonic connective tissue, are loosely located. At the point of contact of the vitelline and amniotic vesicles, a two-layer plate of the ka is formed - the germinal shield. That plate, which is adjacent to the amniotic vesicle, forms the outer part of the germinal shield (ectoderm). The plate of the germinal shield, which is adjacent to the yolk vesicle, is the germinal (intestinal) endoderm. From it develop the epithelial cover of the mucous membrane of the digestive organs (alimentary tract) and respiratory tract, as well as the digestive and some other glands, including the liver and pancreas.

The trophoblast, together with the extra-embryonic mesoderm, form the villous membrane of the embryo - the chorion, which participates in the formation of the placenta ("children's place"), through which the embryo receives nutrition from the mother's body.

At the 3rd week of pregnancy (from the 15th-17th day of embryogenesis), the embryo acquires a three-layer structure, its axial organs develop. The cells of the outer (ectodermal) plate of the germinal shield are displaced towards its posterior end. As a result, a thickening is formed near the ectodermal plate - a primary strip oriented anteriorly. The anterior (cranial) part of the primary strip has a slight elevation - the primary (Hensen's) nodule. The cells of the outer nodule (ectoderm), which lie in front of the primary vesicle, plunge into the gap between the outer (ectodermal) and inner (endodermal) plates and form the chordal (head) process, from which the dorsal string is formed - the chord. The cells of the primary streak, growing in both directions between the outer and inner plates of the germinal shield and on the sides of the notochord, form the middle germinal layer - the mesoderm. The embryo becomes three-layered. At the 3rd week of development, the neural tube begins to form from the ectoderm.

From the back of the endodermal plate, the allantois protrudes into the extraembryonic mesoderm (the so-called amniotic stalk). In the course of the allantois, from the embryo through the amniotic stalk to the chorion villi, blood (umbilical) vessels also sprout, which later form the basis of the umbilical cord.

At the 3rd-4th week of development, the body of the embryo (embryonic shield) gradually separates from the extraembryonic organs (yolk sac, allantois, amniotic stalk). The embryonic shield is bent, a deep furrow is formed on its sides - the trunk fold. This fold delimits the edges of the germ layer from the ammonium. The body of the embryo from a flat shield turns into a three-dimensional one, the ectoderm covers the embryo from all sides.

The endoderm, which is inside the body of the embryo, rolls up into a tube and forms the rudiment of the future intestine.

The narrow opening connecting the embryonic intestine with the yolk sac later turns into the umbilical ring. The epithelium and glands of the gastrointestinal tract and respiratory tract are formed from the endoderm. From the ectoderm, the nervous system, the epidermis of the skin and its derivatives, the epithelial lining of the oral cavity, the anal part of the rectum, the vagina and other organs are formed.

Between the cavity of the primary intestine and the oral fossa in front there is a two-layer (ectoderm and endoderm) anterior (pharyngeal) membrane. Between the intestine and the anal fossa there is an anal membrane, also two-layered. The anterior (pharyngeal) membrane breaks through at 3-4 weeks of development. At the 3rd month, the posterior (anal) membrane breaks. The amnion, filled with amniotic fluid, surrounds the embryo, protecting it from various injuries and concussions. The growth of the yolk sac gradually slows down, and it is reduced.

At the end of the 3rd week of development, mesoderm differentiation begins. The mesenchyme arises from the mesoderm. The dorsal part of the mesoderm, located on the sides of the chord, is subdivided into 43-44 pairs of body segments - somites. Three parts are distinguished in somites. Anterior medial - sclerotome, from which the bones and cartilages of the skeleton develop. Lateral to the sclerotome is the myotome, from which the striated skeletal muscles are formed.

Outside lies the dermatome, from which the skin itself arises.

From the anterior (ventral) non-segmented part of the mesoderm (splanchnotome), two plates are formed. One of them (medial, visceral) is adjacent to the gut and is called splanchnopleura. The other (lateral, external) is adjacent to the wall of the body of the embryo, to the ectoderm and is called the somatopleura. From these plates, the peritoneum, pleura (serous membranes) develop, and the space between the plates turns into the peritoneal, pleural and pericardial cavities. From the mesenchyme of the ventral non-segmented mesoderm (splanchnotome), unstriated smooth muscle tissue, connective tissue, blood and lymphatic vessels, and blood cells are formed. The heart, kidneys, adrenal cortex, gonads, and other structures also develop from the mesenchyme of splanchnotomes.

By the end of the first month of intrauterine development, the laying of the main organs of the embryo, which has a length of 6.5 mm, ends.

On the 5th-8th week, the fin-like rudiments of the upper and then the lower limbs appear in the embryo in the form of skin folds, into which the anlagen of bones, muscles, vessels and nerves later grow.

During the entire fetal period, there is a growth and further development of already formed organs and tissues. The differentiation of the external genital organs begins. Nails are laid on the fingers. At the end of the 5th month, eyebrows and eyelashes appear. At the 7th month, the eyelids open, fat begins to accumulate in the subcutaneous tissue.

After birth, the child grows rapidly, the weight and length of his body, and the surface area of the body increase (Table 1).

Human growth continues during the first 20 years of his life. In men, the increase in body length ends, as a rule, at 20-22 years old, in women - at 18-20 years old. Then, up to 60-65 years, the body length almost does not change. However, in the elderly and senile age (after 60-70 years), due to an increase in the bends of the spinal column and a change in the posture of the body, thinning of the intervertebral discs, flattening of the arches of the foot, the body length decreases by 1-1.5 mm annually.

During the first year of life after birth, the height of the child increases by 21-25 cm.

In the periods of early and first childhood (1 year - 7 years), the growth rate decreases rapidly, at the beginning of the second childhood period (8-12 years), the growth rate is 4.5-5 cm per year, and then increases. In adolescence (12-16 years), the annual increase in body length in boys is on average 5.8 cm, in girls - about 5.7 cm.

Length, body weight and body surface area in different age periods of postnatal ontogenesis Indicators Newborn Age periods / sex (m-male, f-female) 8 years 10 years 12 years 14 years m f m f m f m f f f cm 50.8 55.0 126.3 126.4 136.3 137.3 143.9 147.8 157.0 157.3.5 3.4 26.1 25.6 32.9 31.8 35, 8 38.5 46.1 49, Body weight, kg Surface area 2200 2200 8690 9610 10750 body, cm Indicators Age periods 16 years 18 years 20 years 22 years 24 24-60 years f m f Body length, cm 169.8 160.2 161.8 173.6 162.8 174.7 162.7 174.7 162.8 174.5 162 Body weight, kg 59.1 56.8 67 ,6 70.2 57.1 57.3 71.9 57.5 71.7 56, Surface area 14300 15850 17255 17535 18000 body, cm Morphobiological Data” (1977), “Human Morphology”, ed. Nikityuk, Chtetsova (1990).

At the same time, in girls, the most intensive growth is observed at the age of 10 to 13 years, and in boys - in adolescence. Then growth slows down.

Body weight doubles by 5-6 months after birth.

Body weight triples by one year and increases by about 4 times by two years. The increase in body length and weight is approximately the same speed. The maximum annual increase in body weight is observed in adolescents: in girls at the 13th, and in boys - at the 15th year of life. Body weight increases up to 20-25 years, and then stabilizes.

Stable body weight usually persists until 40-46 years.

It is considered important and physiologically justified to maintain body weight until the end of life within the limits of 19-20 years of age.

After birth, during the period of continuing human growth, each age has its own morphofunctional features.

The spine is devoid of curves, the promontory is only slightly pronounced. The bones that form the pelvic bone are not fused together. The internal organs are relatively larger than those of an adult. So, for example, the mass of the liver Fig. 2. Changes in the proportions of body parts in the process of growth.

KM - the middle line. The numbers at the top show what part of the body the head is. The divisions marked with numbers on the right are the correspondence of the body parts of children and adults;

the numbers below - the age of a newborn child is "/20 of body weight, while in an adult it is "/50. The length of the intestine is 2 times the length of the body, in an adult - 4-4 times. The mass of the brain of a newborn is 13-14% of body weight, and in an adult, only about 2%. The adrenal glands and thymus are large.

In infancy (10 days - 1 year), the child's body grows most rapidly. From about 6 months, the eruption of milk teeth begins. During the first year of life, a number of organs and systems reach sizes typical of an adult (eye, inner ear, central nervous system). During the first years of life, the musculoskeletal system, digestive, and respiratory systems grow rapidly and develop.

In the period of early childhood (1-3 years), all milk teeth erupt and the first “rounding” occurs, i.e. the increase in body weight outstrips the growth of the body in length. The mental development of the child, speech, memory is rapidly progressing.

The child begins to navigate in space. During the 2nd-3rd years of life, the growth in length prevails over the increase in body weight. At the end of the period, the eruption of permanent teeth begins. In connection with the rapid development of the brain, whose mass reaches 1100-1200 g by the end of the period, mental abilities and visual thinking develop rapidly, the ability to recognize, orientation in time, in the days of the week is retained for a long time.

In early and first childhood (4-7 years), sexual differences (except for primary sexual characteristics) are almost not expressed. In the period of second childhood (8-12 years), growth in width again predominates, but at this time puberty begins, and by the end of the period, the growth of the body in length intensifies, the rate of which is higher in girls.

The mental development of children is progressing. Orientation towards months and calendar days develops.

Puberty begins, earlier in girls, which is associated with increased secretion of female sex hormones. In girls at the age of 8-9, the pelvis begins to expand and the hips become rounded, the secretion of the sebaceous glands increases, and pubic hair develops. In boys, at the age of 10-11 years, the growth of the larynx, testicles and penis begins, which by the age of 12 increases by 0.5-0.7 cm.

In adolescence (12-16 years), the genitals grow and develop rapidly, secondary sexual characteristics intensify. In girls, the amount of hair on the skin of the pubic region increases, hair appears in the armpits, the size of the genital organs and mammary glands increase, the alkaline reaction of the vaginal secretion becomes acidic, menstruation appears, and the size of the pelvis increases. In boys, the testicles and penis rapidly increase, at first the pubic hair develops according to the female type, the mammary glands swell. By the end of adolescence (15-16 years), hair growth begins on the face, body, in the armpits, and on the pubis - according to the male type, the skin of the scrotum is pigmented, the genitals increase even more, the first ejaculations occur (involuntary ejaculations).

In adolescence, mechanical and verbal-logical memory develops.

Adolescence (16-21 years) coincides with the period of maturation. At this age, the growth and development of the organism is basically completed, all apparatuses and organ systems practically reach morphological and functional maturity.

The structure of the body in adulthood (22-60 years old) changes little, and in the elderly (61-74 years old) and senile (75 years old), rearrangements characteristic of these ages are traced, which are studied by a special science - gerontology (from the Greek. geron - old man). The time limits of aging vary widely in different individuals. In old age, there is a decrease in the adaptive capabilities of the body, a change in the morphofunctional parameters of all apparatuses and organ systems, among which the most important role belongs to the immune, nervous and circulatory systems.

An active lifestyle and regular physical activity slow down the aging process. However, this is possible within the limits due to hereditary factors.

Sexual characteristics distinguish men from women (Table 1).

2). They are divided into primary (genital organs) and secondary (development of pubic hair, development of mammary glands, voice changes, etc.).

In anatomy, there are concepts about body types. Physique is determined by genetic (hereditary) factors, the influence of the external environment, and social conditions. There are three types of human physique: mesomorphic, brachymorphic and dolichomorphic. With mesomorphism (from the Greek. mesos - average, morphe - shape, appearance) body type (normosthenics) anatomical features Table Some gender differences between men (m) and women (f) (relative Shorter Longer measurements) Limbs (%%) Longer Shorter Shoulders Wider Tighter Pelvis Already Wider Chest Longer, wider Shorter, narrower Abdomen Shorter Longer Muscle mass More Less Subcutaneous fat Less More fiber Skin Thicker Thinner Hair More on the face, Less on the the trunk, the end-abdomen are absent, abundant on the pubis and abdomen up to the navel, the structure of the body approaches the average indicators of the norm (taking into account age, gender). Persons of a brachymorphic (from the Greek brachys - short) body type (hypersthenics) are short in stature, have a wide body, and tend to be overweight. Their diaphragm is located high, the heart lies on it almost transversely, the lungs are short, the muscles are well developed. Individuals with a dolichomorphic body type (from the Greek dolichos - long) are tall and have long limbs. The muscles are poorly developed. The diaphragm is low, the lungs are long, the heart is located almost vertically.

Human anatomy studies the structure of a normal (averaged) person, therefore such anatomy is called normal. For the convenience of studying the position of organs and body parts, three mutually perpendicular planes are used. The sagittal plane (from the Greek sagitta - arrow) vertically cuts the body from front to back. The frontal plane (from Latin from - forehead) is located perpendicular to the sagittal plane, oriented from right to left.

The horizontal plane occupies a perpendicular position with respect to the first two, it separates the upper part of the body from the lower.

In anatomy, the terms middle (medial, lying closer to the median plane) and lateral (lateral, located at a distance from the median plane) are distinguished. To designate parts of the upper and lower limbs, the concepts of proximal - located closer to the beginning of the limb, and distal - located farther from the body are used.

When studying anatomy, terms such as right and left, large and small, superficial and deep are used.

When determining the position of organs in a living person, the projections of their boundaries on the surface of the body use vertical lines drawn through certain points. The anterior median line is drawn along the middle of the anterior surface of the body. The posterior median line runs along the spinous processes of the vertebrae. Both of these lines connect the right half of the body with the left. The right and left sternal (oblosternal) lines run along the corresponding edges of the sternum. The midclavicular line runs vertically through the middle of the clavicle. Axillary (anterior, middle and posterior) lines are drawn through the middle and the corresponding edges of the axillary fossa. The scapular line passes through the inferior angle of the scapula. The paravertebral line is drawn next to the spine through the costal-transverse joints.

Questions for repetition and self-control:

1. What is a zygote? What and where is it formed from?

2. What embryonic structures form the ectoderm and endoderm? Which organs of them develop in the future?

3. When and from what is the middle germ layer formed?

4. What parts are isolated from somites and from splanchnotome?

5. What factors influence the development of the embryo?

6. What anatomical features are typical for a newborn?

7. What systems and apparatuses of organs grow and develop faster in children, adolescents, in adolescence?

8. Name the body types you know and their distinctive features.

STRUCTURE OF THE HUMAN BODY The human body, which is a single, integral, complex system, consists of organs and tissues. Organs that are built from tissues are combined into systems and apparatuses. Tissues, in turn, consist of various types of cells and intercellular substance.

CELLS A cell is an elementary, universal unit of living matter. The cell has an ordered structure, is able to receive energy from outside and use it to perform the functions inherent in each cell. Cells actively respond to external influences (irritations), participate in metabolism, have the ability to grow, regenerate, reproduce, transfer genetic information, and adapt to environmental conditions.

Cells in the human body are diverse in shape, they can be flat, round, ovoid, spindle-shaped, cubic, process. The shape of cells is determined by their position in the body and function.

Cell sizes vary from a few micrometers (for example, a small lymphocyte) to 200 microns (an egg).

The intercellular substance is a product of the vital activity of cells and consists of the main substance and various connective tissue fibers located in it.

Despite the great diversity, all cells have common structural features and consist of a nucleus and cytoplasm enclosed in a cell membrane - the cytolemma (Fig. 3). The cell membrane, or cell membrane (lemma, plasmalemma), delimits the cell from the external environment. The thickness of the cytolemma is 9-10 nm (1 nanometer is equal to m or 0.002 microns). The cytolemma is built from protein and lipid molecules and is a three layered structure, the outer surface of which is covered with fine fibrillar glycocalyx. The glycocalyx contains various carbohydrates that form long branching chains of polysaccharides. These polysaccharides are associated with protein molecules that are part of the cytolemma. In the cytolemma, the outer and inner electron-dense lipid layers (plates) are about 2.5 nm thick, and the middle, electron-transparent layer (hydrophobic zone of lipid molecules) is about 3 nm thick. The bilipid layer of the cytolemma contains protein molecules, some of which pass through the entire thickness of the cell membrane.

The cytolemma not only separates the cell from the external environment. It protects the cell, performs receptor functions (perceives the effects of the external environment for the cell), and a transport function. Through the cytolemma, various substances (water, low molecular weight compounds, ions) are transferred both inside the cell and out of the cell. When energy is consumed (ATP splitting), various organic substances (amino acids, sugars, etc.) are actively transported through the cytolemma.

The cytolemma also forms intercellular connections (contacts) with neighboring cells. Contacts can be simple or complex. Simple connections are in the form of a jagged suture, when the outgrowths (teeth) of the cytolemma of one cell are introduced between the outgrowths of a neighboring cell. There is an intercellular gap 15–20 nm wide between the cytolemmas of neighboring cells. Complex contacts are formed by Fig. 3. Scheme of the ultramicroscopic structure of the cell: 1 - cytolemma (plasma membrane), 2 - pinocytic vesicles, 3 - centrosome (cell center, cytocenter), 4 - hyaloplasm, 5 - endoplasmic reticulum (a - membranes of the endoplasmic reticulum, b - ribosomes ), 6 - nucleus, 7 - connection of the perinuclear space with the cavities of the endoplasmic reticulum, 8 - nuclear pores, 9 - nucleolus, 10 - intracellular reticular apparatus (Golgi complex), 11 - secretory vacuoles, 12 - mitochondria, 13 - lysosomes, 14 - three successive stages of phagocytosis, 15 - connection of the cell membrane (cytolemma) with the membranes of the endoplasmic reticulum or tightly adjacent cell membranes of neighboring cells (tight junctions), or the presence of a fine fibrillar substance (desmosomes) between neighboring cells. Conductive junctions include synapses and gap junctions - nexuses. Synapses have a gap between the cytolemma of neighboring cells through which transport (transfer of excitation or inhibition) occurs in only one direction. In nexuses, the slit-like space between neighboring cytolemmas is divided into separate short sections by special protein structures.

The cytoplasm is heterogeneous in composition; it includes hyaloplasm and organelles and inclusions in it.

Hyaloplasm (from the Greek hyalinos - transparent) forms the matrix of the cytoplasm, its internal environment. Outside, it is delimited by a cell membrane - the cytolemma. Hyaloplasma has the appearance of a homogeneous substance; it is a complex colloidal system consisting of proteins, nucleic acids, polysaccharides, enzymes, and other substances.

The most important role of the hyaloplasm is to unite all intracellular structures and to ensure their chemical interaction with each other. In the hyaloplasm, proteins are synthesized that are necessary for the vital activity and functions of the cell. Glycogen, fatty inclusions are deposited in the hyaloplasm, an energy reserve is contained - molecules of adenosine triphosphoric acid (ATP).

The hyaloplasm contains general purpose organelles that are present in all cells, as well as non-permanent structures - cytoplasmic inclusions.

The organelles include mitochondria, the internal retinal apparatus (Golgi complex), the cytocenter (cell center), granular and nongranular endoplasmic reticulum, ribosomes, and lysosomes. Inclusions include glycogen, proteins, fats, vitamins, pigment substances and other structures.

Organelles are the structures of the cytoplasm that are constantly found in cells and perform certain vital functions. There are membranous and non-membrane organelles. In the cells of certain tissues, special organelles are found, for example, fibrils in the structures of muscle tissue.

Membrane organelles are closed single or interconnected microscopic cavities, delimited by a membrane from the surrounding hypoplasm. Membrane organelles are mitochondria, internal reticular apparatus (Golgi complex), endoplasmic reticulum, lysosomes, peroxisomes. The endoplasmic reticulum is subdivided into granular and nongranular. Both of them are formed by cisterns, vesicles and channels, which are limited by a membrane about 6-7 nm thick. The endoplasmic reticulum, to the membranes of which ribosomes are attached, is called the granular (rough) endoplasmic reticulum. If there are no ribosomes on the membrane surface, this is a smooth endoplasmic reticulum.

The membranes of the endoplasmic reticulum are involved in the transport of substances in the cell. Protein synthesis is carried out on the ribosomes of the granular endoplasmic reticulum, and glycogen and lipids are synthesized on the membranes of the smooth endoplasmic reticulum.

The internal reticular apparatus (Golgi complex) is formed by membranes of tightly lying flat cisterns and numerous small vesicles (vesicles) located along their periphery. The places of accumulation of these membranes are called dictyosomes. One dictyosome includes 5 flat membranous cisterns separated by layers of hyaloplasm. The membranes of the internal retinal apparatus perform the functions of accumulation, chemical rearrangement of substances that are synthesized by the endoplasmic reticulum.

In the cisterns of the Golgi complex, polysaccharides are synthesized, which form a complex with proteins. The Golgi complex is involved in the excretion of synthesized substances outside the cell and is the source of the formation of cellular lysosomes.

Mitochondria have a smooth outer membrane and an inner membrane with protrusions in the form of ridges (cristae) inside the mitochondria. Folding of the inner mitochondrial membrane significantly increases its inner surface. The outer mitochondrial membrane is separated from the inner one by a narrow intermembrane space. The mitochondrial cavity between the cristae is filled with a matrix having a fine grained structure. It consists of DNA molecules (deoxyribonucleic acid) and mitochondrial ribosomes. The diameter of mitochondria averages 0.5 µm, and the length reaches 7-10 µm. The main function of mitochondria is the oxidation of organic compounds and the use of the released energy for the synthesis of ATP molecules.

Lysosomes are spherical structures 0.2-0.4 microns in size, limited by a membrane. The presence of hydrolytic enzymes (hydrolases) in lysosomes that cleave various biopolymers indicates their participation in the processes of intracellular digestion.

Peroxisomes (microbodies) are small vacuoles 0.3–1.5 µm in size, bounded by a membrane and containing a granular matrix. This matrix contains catalase, which destroys hydrogen peroxide, which is formed under the action of enzymes for the oxidative deamination of amino acids.

Non-membrane organelles include ribosomes, microtubules, centrioles, microfilaments, and other formations. Ribosomes are the elementary apparatus for the synthesis of protein, polypeptide molecules. Ribosomes consist of ribonucleoprotein granules (20-25 nm in diameter), in the formation of which proteins and RNA molecules participate.

Along with single ribosomes, cells contain groups of ribosomes (polysomes, polyribosomes).

Microtubules are located in the cytoplasm of cells. They are hollow cylinders with a diameter of about 24 nm. Microtubules are formed by tubulin proteins.

In the cytoplasm, microtubules form the cytoskeleton and are involved in the motor functions of cells. Microtubules maintain the shape of cells and promote their oriented movements. Microtubules are part of centrioles, spindles of cell division, basal bodies, flagella, and cilia.

Centrioles are hollow cylinders about 0.25 µm in diameter and up to 0.5 µm long. The walls of the centrioles are built of microtubules, which form nine triplets (9*3) connected to each other. Two centrioles lying at right angles to each other form a diplosome. Around the centrioles (diplosomes) there is a centrosphere in the form of a structureless dense rim with radially thin fibrils extending from it.

Centrioles and centrosphere together form the cell center. In preparation for mitotic division, the number of centrioles in the cell doubles.

Centrioles are involved in the formation of the spindle of cell division and the apparatus of its movement - cilia and flagella. Cilia and flagella are cylindrical outgrowths of the cytoplasm, in the center of which is a system of microtubules.

Microfilaments are thin (5-7 nm) protein filaments located in the form of bundles or layers mainly in the peripheral parts of the cell. Microfilaments include various contractile proteins: actin, myosin, tropomyosin. Microfilaments perform the musculoskeletal function of cells. Intermediate filaments, or microfibrils, about 10 nm thick, have a different composition in different cells.

In epithelial cells, filaments are built from keratin proteins, in muscle cells - from desmin, in nerve cells - from neurofibril proteins. Intermediate microfilaments are also the supporting frame structures of cells.

Inclusions of the cytoplasm of cells serve as temporary structures, they are formed as a result of the activity of the cell. There are trophic, secretory and pigment inclusions. Trophic inclusions are protein, fat and carbohydrate. They serve as reserves of nutrients and are accumulated by the cell. Secretory inclusions are products of the function of glandular cells, contain biologically active substances necessary for the body. Pigmented inclusions are colored substances necessary for the body that accumulate in the cell. The pigment can be of exogenous origin (dyes, etc.) and endogenous (melanin, hemoglobin, bilirubin, lipofuscin).

Cell nucleus. The nucleus is an essential element of the cell, it contains genetic information and regulates protein synthesis. Genetic information is embedded in deoxyribonucleic acid (DNA) molecules.

When a cell divides, this information is transmitted in equal amounts to the daughter cells. The nucleus has its own apparatus for protein synthesis, which controls the synthetic processes in the cytoplasm. In the nucleus on DNA molecules, various types of ribonucleic acid (RNA) are reproduced - informational, transport, ribosomal.

The nucleus of a nondividing cell (interphase) often has a spherical or ovoid shape and consists of chromatin, nucleolus, karyoplasm (nucleoplasm), delimited from the cytoplasm by the nuclear envelope.

Chromatin of the interphase nucleus is a chromosomal material - these are loosened, decondensed chromosomes. Decondensed chromosomes are called euchromatin. Thus, chromosomes in cell nuclei can be in two structural and functional states. In the decondensed form, the chromosomes are in a working, active state. At this time, they participate in the processes of transcription (reproduction), replication (from Latin - repetition) of nucleic acids (RNA, DNA). Chromosomes in a condensed (dense) state are inactive; they participate in the distribution and transfer of genetic information to daughter cells during cell division. In the initial phases of mitotic cell division, chromatin condenses to form visible chromosomes. In humans, somatic cells contain 46 chromosomes - 22 pairs of homologous chromosomes and two sex chromosomes. In women, the sex chromosomes are paired (XX chromosomes), in men - unpaired (XY chromosomes).

The nucleolus is a dense, intensely stained formation in the nucleus, round in shape, 1-5 microns in size.

The nucleolus consists of filamentous structures - nucleoproteins and intertwining strands of RNA, as well as precursors of ribosomes. The nucleolus serves as a site for the formation of ribosomes, on which polypeptide chains are synthesized in the cytoplasm of cells.

The nucleoplasm, the electron-transparent part of the nucleus, is a colloidal solution of proteins that surrounds the chromatin and nucleolus.

The nuclear envelope (nucleolemma) consists of the outer nuclear membrane and the inner nuclear membrane separated by the perinuclear space. The nuclear envelope contains pores containing protein granules and filaments (pore complex). Selective transport of proteins occurs through nuclear pores, which ensures the passage of macromolecules into the cytoplasm, as well as the exchange of substances between the nucleus and cytoplasm.

Cell division (cell cycle) The growth of the organism, the increase in the number of cells, their reproduction occurs by division. Mitosis and meiosis are the main methods of cell division in the human body. The processes occurring during these methods of cell division proceed in the same way, but they lead to different results. Mitotic cell division leads to an increase in the number of cells, to the growth of the organism. In this way, cell renewal is ensured when they are worn out or die. (Currently, it is known that epidermal cells live 3-7 days, erythrocytes - up to 4 months. Nervous and muscle cells (fibers) live throughout a person's life.) Due to mitotic division to black cells, they receive a set of chromosomes identical to ma Terinsky.

During meiosis, which is observed in germ cells, as a result of their division, new cells are formed with a single (haploid) set of chromosomes, which is important for the transmission of genetic information. When one sex cell merges with a cell of the opposite sex (during fertilization), the set of chromosomes doubles, becomes complete, double (diploid).

Meiosis is a kind of division when four daughter nuclei are formed from one, each of which contains half as many chromosomes as in the mother nucleus. During meiosis, two successive (meiotic) cell divisions occur. As a result, a single (haploid) set (In) is formed from a double (diploid) number of chromosomes (2n). Meiosis occurs only during the division of germ cells, while maintaining a constant number of chromosomes, which ensures the transfer of hereditary information from one cell to another. In all cells, during reproduction (division), changes are observed that fit within the framework of the cell cycle.

The cell cycle is the name given to the processes that occur in a cell during the preparation of the cell for division and during division, as a result of which one cell (maternal) divides into two daughter cells (Fig. 4). In the cell cycle, the preparation of the cell for division (interphase) and mitosis (the process of cell division) are distinguished.

In the interphase, which lasts approximately 20-30 hours, the mass of the cell and all its structural components, including centrioles, doubles. Replication (repetition) of nucleic acid molecules occurs. The parent DNA strand serves as a template for the synthesis of daughter deoxyribonucleic acids. As a result of replication, each of the two daughter DNA molecules consists of one old and one new strand. During the period of preparation for mitosis, the proteins necessary for cell division (mitosis) are synthesized in the cell. By the end of the interphase, the chromatin in the nucleus is condensed.

Mitosis (from the Greek mitos - thread) is the period when the mother cell is divided into two daughter cells.

Mitotic cell division provides a uniform distribution of cell structures, its nuclear substance - chromatin - between two daughter cells. Duration 4. Stages of mitosis. The condensation of chromatin with the formation of chromosomes, the formation of a fission spindle, and the uniform distribution of chromosomes and centrioles over two daughter cells are shown.

A - interphase, - prophase, B - metaphase, D - anaphase, D - telophase, E - late telophase.

1 - nucleolus, 2 - fission spindle, 4 - star, nuclear membrane, 6 - 7 - continuous microtubules, 8, 9 - chromosomes, - chromosomal microtubules, - formation of the nucleus, 12 - cleavage furrow, 13 - actin bundle strands, 14 - residual (median) mitotic body - from 30 minutes to 3 hours. Mitosis is divided into prophase, metaphase, anaphase, and telophase.

In prophase, the nucleolus gradually disintegrates, centrioles diverge towards the poles of the cells.

In metaphase, the nuclear membrane is destroyed, the chromosome threads are directed to the poles, maintaining a connection with the equatorial region of the cell. The structures of the endoplasmic reticulum and the Golgi complex disintegrate into small vesicles (vesicles), which, together with mitochondria, are distributed into both halves of the dividing cell. At the end of metaphase, each chromosome begins to split along the longitudinal cleft into two new daughter chromosomes.

In anaphase, the chromosomes separate from each other and diverge towards the poles of the cell at a rate of up to 0.5 µm/min.

In the telophase, the chromosomes that have diverged to the poles of the cell decondense, pass into chromatin, and transcription (production) of RNA begins. The nuclear membrane, the nucleolus is formed, the membrane structures of future daughter cells are quickly formed. On the surface of the cell, along its equator, a constriction appears, which deepens, the cell is divided into two daughter cells.

Questions for repetition and self-control:

1. Name the structural elements of the cell.

2. What functions does the cell perform?

3. List the membrane and non-membrane cell organelles, name their functions.

4. What elements does the cell nucleus consist of, what functions does it perform?

5. What are the types of cell connections with each other?

6. What is the cell cycle, what periods (phases) are distinguished in it (in this cycle)?

7. What is meiosis, how does it differ from mitosis?

TISSUE Cells and their derivatives combine to form tissues.

A tissue is a set of cells and intercellular substance that has developed in the process of evolution and has a common origin, structure and functions. According to morphological and physiological characteristics, four types of tissues are distinguished in the human body: epithelial, connective, muscle and nervous.

Epithelial tissue The epithelium of the epithelial tissue forms the surface layers of the skin, covers the mucous membrane of the hollow internal organs, the surface of the serous membranes, and also forms glands. In this regard, cover epithelium and glandular epithelium are distinguished.

The integumentary epithelium occupies a boundary position in the body, separating the internal environment from the external one, protects the body from external influences, performs the functions of metabolism between the body and the external environment.

The glandular epithelium forms glands that differ in shape, location and function. Epithelial cells (glandulocytes) of the glands synthesize and secrete substances - secrets involved in various functions of the body. Therefore, the glandular epithelium is also called the secretory epithelium.

The integumentary epithelium forms a continuous layer consisting of densely arranged cells connected to each other using various types of contacts. Epitheliocytes always lie on the basement membrane rich in carbohydrate-protein-lipid complexes, on which its selective permeability depends. The basal membrane separates the epithelial cells from the underlying connective tissue. The epithelium is richly supplied with nerve fibers and receptor endings that transmit signals about various external influences to the central nervous system. The nutrition of the cells of the integumentary epithelium is carried out by diffusion of tissue fluid from the underlying connective tissue.

According to the ratio of epithelial cells to the basement membrane and their position on the free surface of the epithelial layer, single-layer and stratified epithelium are distinguished (Fig. 5). In a single-layer epithelium, all cells lie on the basement membrane, in multilayer epithelium, only the deepest layer is adjacent to the basement membrane.

A single-layered epithelium, in the cells of which the nuclei are located at the same level, is called single-row. The epithelium, whose cell nuclei lie at different levels, is called multi-row. Stratified epithelium is non-keratinizing (stratified squamous non-keratinizing), as well as keratinizing (stratified squamous keratinizing), in which superficially located cells become keratinized, turn into horny scales. The transitional epithelium is so named because its structure changes depending on the stretching of the walls of the organ that this epithelium covers (for example, the epithelial lining of the bladder mucosa).

According to their shape, epithelial cells are classified into squamous, cuboidal, and prismatic. In epithelial cells, a basal part is isolated, facing the basement membrane, and an apical part, directed to the surface of the layer of the integumentary epithelium. In the basal part there is a nucleus, in the apical part there are cell organelles, inclusions, including secretory granules in Fig. 5. Scheme of the structure of epithelial tissue:

A - simple squamous epithelium (mesothelium);

B - simple cubic epithelium;

B - simple columnar epithelium;

G - ciliated epithelium;

D - transitional epithelium;

E - non-keratinized multilayer (flat) squamous epithelium of the glandular epithelium. On the apical part, there may be microvilli - outgrowths of the cytoplasm in specialized epithelial cells (ciliated epithelium of the respiratory tract).

Integumentary epithelium in case of damage is able to quickly recover by the mitotic method of cell division. In a single layer epithelium, all cells have the ability to divide, in a multilayer epithelium, only basally located cells. Epithelial cells, intensively multiplying along the edges of the injury, seem to crawl onto the wound surface, restoring the integrity of the epithelial cover.

Connective tissues Connective tissue is formed by cells and intercellular substance, which always contains a significant amount of connective tissue fibers. Connective tissue, having a different structure, location, performs mechanical functions (support), trophic - nutrition of cells, tissues (blood), protective (mechanical protection and phagocytosis).

In accordance with the peculiarities of the structure and functions of the intercellular substance and cells, the connective tissue proper, as well as skeletal tissues and blood, are isolated.

Connective tissue proper Connective tissue proper accompanies blood vessels up to capillaries, fills gaps between organs and tissues in organs, and underlies epithelial tissue. Connective tissue itself is divided into fibrous connective tissue and connective tissue with special properties (reticular, adipose, pigmented).

Fibrous connective tissue, in turn, is subdivided into loose and dense, and the latter into unformed and formed. The classification of fibrous connective tissue is based on the principle of the ratio of cells and intercellular, fiber structures, as well as the location of connective tissue fibers.

Loose fibrous connective tissue is present in all organs near the blood and lymphatic vessels, nerves and forms the stroma of many organs (Fig. 6). The main cellular elements of loose fibrous connective tissue are fibroblasts. Intercellular structures are represented by the main substance and collagen (adhesive) and elastic fibers located in it. The main substance is a homogeneous colloidal mass, which consists of acidic and neutral polysaccharides in complex with proteins. These polysaccharides are called glycosaminoglycans, proteoglycans, including hyaluronic acid. The liquid part of the main substance is tissue fluid.

Mechanical, strength properties of connective tissue give collagen and elastic fibers. Collagen protein is the basis of collagen fibers. Each collagen fiber consists of individual collagen fibrils about 7 nm thick. Collagen fibers 6. The structure of loose fibrous connective tissue:

1 - macrophage, 2 - amorphous intercellular (basic) substance, 3 - plasmocyte (plasma cell), 4 - lipocyte (fat cell), 5 - blood vessel, 6 - myocyte, 7 - pericyte, 8 - endotheliocyte, 9 - fibroblast, 10 - elastic fiber, 11 - tissue basophil, 12 - collagen fiber are characterized by high mechanical tensile strength. They are combined into bundles of various thicknesses.

Elastic fibers determine the elasticity and extensibility of connective tissue. They consist of amorphous elastin protein and filamentous, branching fibrils.

Connective tissue cells are young functionally active fibroblasts and mature fibrocytes.

Fibroblasts take part in the formation of intercellular substance and collagen fibers. Fibroblasts have a spindle shape, basophilic cytoplasm, they are capable of reproduction by mitosis. Fibrocytes differ from fibroblasts in the poor development of membrane organelles and low metabolic rate.

The connective tissue contains specialized cells, including blood cells (leukocytes) and immune system cells (lymphocytes, plasma cells). Loose connective tissue contains mobile cellular elements - macrophages and mast cells.

Macrophages are actively phagocytic cells, 10–20 µm in size, containing numerous organelles for intracellular digestion and synthesis of various antibacterial substances, having numerous villi on the surface of the cell membrane.

Mast cells (tissue basophils) synthesize and accumulate biologically active substances (heparin, serotonin, dopamine, etc.) in the cytoplasm. They are regulators of local homeostasis in the connective tissue.

The loose fibrous connective tissue also contains fat cells (adipocytes) and pigment cells (pigmentocytes).

Dense fibrous connective tissue consists mainly of fibers, a small number of cells and the main amorphous substance. A dense irregular and dense formed fibrous connective tissue is distinguished. The first of them (unformed) is formed by numerous fibers of various orientations and has complex systems of intersecting bundles (for example, the reticular layer of the skin). In a dense, formed fibrous connective tissue, the fibers are located in one direction, in accordance with the action of the tension force (muscle tendons, ligaments).

Connective tissue with special properties is represented by reticular, adipose, mucous and pigment tissues.

Reticular connective tissue consists of reticular cells and reticular fibers. The fibers and the outgrowth of reticular cells form a loose network. The reticular tissue forms the stroma of the hematopoietic organs and organs of the immune system and creates a microenvironment for the blood and lymphoid cells developing in them.

Adipose tissue consists mainly of fat cells. It performs thermoregulatory, trophic, shaping functions. Fat is synthesized by the cells themselves, so the specific function of adipose tissue is the accumulation and metabolism of lipids. Adipose tissue is located mainly under the skin, in the omentum and in other fat depots. Adipose tissue is used during starvation to cover the body's energy costs.

Mucous connective tissue in the form of large outgrowths of cells (mucocytes) and intercellular substance, rich in hyaluronic acid, is present in the umbilical cord, protecting the umbilical blood vessels from compression.

Pigmented connective tissue contains a large number of melanocyte pigment cells (iris, age spots, etc.), in the cytoplasm of which there is melanin pigment.

Skeletal tissues Skeletal tissues include cartilaginous and bone tissues, which perform mainly supporting, mechanical functions in the body, and also take part in mineral metabolism.

Cartilage tissue consists of cells (chondrocytes, chondroblasts) and intercellular substance. The intercellular substance of cartilage, which is in a gel state, is formed mainly by glycosaminoglycans and proteoglycans. Cartilage contains a large amount of fibrillar proteins (mainly collagen). The intercellular substance has a high hydrophilicity.

Chondrocytes have a round or oval shape, they are located in special cavities (lacunae), they produce all the components of the intercellular substance. Chondroblasts are young cartilage cells. They actively synthesize the intercellular substance of cartilage and are also capable of reproduction. Due to chondroblasts, peripheral (appositional) growth of cartilage occurs.

2 R. The layer of connective tissue covering the surface of the cartilage is called the perichondrium. In the perichondrium, the outer layer is isolated - fibrous, consisting of dense fibrous connective tissue and containing blood vessels and nerves. The inner layer of the perichondrium is chondrogenic, containing chondroblasts and their precursors, prechondroblasts. The perichondrium provides appositional growth of the cartilage, its vessels carry out diffuse nutrition of the cartilage tissue and the removal of metabolic products.

According to the structural features of the intercellular substance, hyaline, elastic and fibrous cartilage are isolated.

Hyaline cartilage is transparent and blue-white in color. This cartilage is found at the junction of the ribs with the sternum, on the articular surfaces of the bones, at the junction of the epiphysis with the diaphysis in tubular bones, in the skeleton of the larynx, in the walls of the trachea, bronchi.

Elastic cartilage in its intercellular substance, along with collagen fibers, contains a large number of elastic fibers. The auricle, some small cartilages of the larynx, and the epiglottis are built from elastic cartilage.

Fibrous cartilage in the intercellular substance contains a large amount of collagen fibers. Fibrous rings of intervertebral discs, articular discs and menisci are built from fibrous cartilage.

Bone tissue is built from bone cells and intercellular substance containing various salts and connective tissue fibers. The location of bone cells, the orientation of the fibers and the distribution of salts provide bone tissue with hardness and strength. The organic substances of the bone are called ossein (from Latin os - bone). The inorganic substances of the bone are salts of calcium, phosphorus, magnesium, etc. The combination of organic and inorganic substances makes the bone strong and elastic. In childhood, there are more organic substances in the bones than in adults, so bone fractures are rare in children. In elderly, old people, the amount of organic matter in the bones decreases, the bones become more fragile, brittle.

Bone cells are osteocytes, osteoblasts and osteoclasts.

Osteocytes are mature, incapable of dividing, sprout bone cells from 22 to 55 microns in length, with a large ovoid nucleus. They are spindle-shaped and lie in bony cavities (lacunae). Bone tubules, containing processes of osteocytes, depart from these cavities.

Osteoblasts are young bone tissue cells with a rounded nucleus. Osteoblasts are formed from the germinal (deep) layer of the periosteum.

Osteoclasts are large multinucleated cells up to 90 µm in diameter. They are involved in the destruction of bone and calcification of cartilage.

There are two types of bone tissue - lamellar and lamellar (fine-fibred) bone tissue consists of bone plates built from mineralized intercellular substance, bone cells and collagen fibers located in it. Fibers in neighboring plates have different orientations. The compact (dense) and spongy substance of the bones of the skeleton are built from lamellar bone tissue. The compact substance forms the diaphyses (middle part) of tubular bones and the surface plate of their epiphyses (ends), as well as the outer layer of flat and other bones. The spongy substance forms beams (beams) located between the plates of the compact substance in the epiphyses and other bones.

The beams (beams) of the spongy substance are located in different directions, which correspond to the direction of the lines of compression and tension of the bone tissue (Fig. 7).

The compact substance is formed by concentric plates, which, in an amount of 4 to 20, surround the blood vessels passing into the bones. The thickness of one such concentric plate is from 4 to 15 microns. The tubular cavity, in which vessels with a diameter of up to 100-110 microns pass, is called the osteon canal. The entire structure around this canal is called the osteon, or Haversian system (structural and functional unit of the bone). Differently located bone plates between adjacent osteons are called intermediate, or intercalary, plates.

The inner layer of compact bone substance is formed by the inner surrounding plates. These plates are a product of the bone-forming function of the endosteum - a thin connective tissue sheath covering the inner surface of the bone (the walls of the medullary cavity and cells of the spongy substance). The outer layer of compact bone substance is formed by the outer surrounding plates, formed by the inner bone-forming layer above the bones. The outer layer of the periosteum is coarse fibrous, fibrous. This layer is rich in nerve fibers, blood vessels, which not only feed above the bone, but also penetrate into the bone through nutrient holes on the surface of the bone. With the surface of the bone, the periosteum is firmly fused with the help of thin connections 7. The structure of the tubular bone.

1 - periosteum, 2 - compact bone substance, 3 - layer of outer surrounding plates, 4 - osteons, 5 - layer of inner surrounding plates, 6 - medullary cavity, 7 - bone crossbars of cancellous bone 8. Blood cells:

1 - basophilic granulocyte, 2 - acidophilic granulocyte, 3 - segmented neutrophilic granulocyte, 4 - erythrocyte, 5 - monocyte, 6 - platelets, 7 - lymphocyte of filamentous fibers (Sharpey's), penetrating from the periosteum into the bone.

Blood and its functions Blood is a type of connective tissue that has a liquid intercellular substance - plasma, in which there are cellular elements - erythrocytes and other cells (Fig. 8). The function of blood is to carry oxygen and nutrients to organs and tissues and remove metabolic products from them.

Blood plasma is the liquid that remains after the removal of formed elements from it. Blood plasma contains 90-93% water, 7-8% of various proteins (albumins, globulins, lipoproteins), 0.9% salts, 0.1% glucose. Blood plasma also contains enzymes, hormones, vitamins and other substances necessary for the body.

Blood plasma proteins are involved in the processes of blood coagulation, maintain the constancy of its reaction (pH), contain immunoglobulins involved in the protective reactions of the body, provide blood viscosity, constancy of its pressure in the vessels, and prevent erythrocyte sedimentation.

The content of glucose in the blood of a healthy person is 80-120 mg% (4.44-6.66 mmol/l). A sharp decrease in the amount of glucose in the blood (up to 2.22 mmol/l) leads to a sharp increase in the excitability of brain cells. The person may have seizures. A further decrease in the content of glucose in the blood leads to impaired respiration, blood circulation, loss of consciousness, and even death.

The mineral substances of blood plasma are NaCl, KC1, CaC12, NaHCO2, NaH2PO4 and other salts, as well as Na+, Ca2+, K+ ions. The constancy of the ionic composition of the blood ensures the stability of the osmotic pressure and the preservation of the volume of fluid in the blood and body cells.

Bleeding and loss of salts are dangerous for the body, for cells. Therefore, in medical practice, an isotonic saline solution is used, which has the same osmotic pressure as blood plasma (0.9% NaCl solution).

More complex solutions containing a set of salts necessary for the body are called not only isotonic, but also isoionic. Blood substitute solutions containing not only salts, but also proteins and glucose are used.

If erythrocytes are placed in a hypotonic solution with a low salt concentration, in which the osmotic pressure is low, then water penetrates into the erythrocytes. Erythrocytes swell, their cytolemma breaks, hemoglobin enters the blood plasma and stains it. This red-colored plasma is called lacquer blood.

In a hypertonic solution with a high salt concentration and high osmotic pressure, water leaves the erythrocytes and they shrivel.

The formed elements (cells) of the blood include erythrocytes, leukocytes, platelets (platelets).

Erythrocytes (red blood cells) are nuclear-free cells that cannot divide. The number of erythrocytes in 1 µl of blood in adult men ranges from 3.9 to 5.5 million (5.0 * 1012 / l), in women - from 3 to 4.9 million (4.5 x At In some diseases, as well as in severe blood loss, the number of red blood cells decreases.At the same time, the hemoglobin content in the blood decreases.This condition is called anemia (anemia).

In a healthy person, the lifespan of erythrocytes is up to 120 days, and then they die, are destroyed in the spleen. Approximately 10-15 million red blood cells die within 1 second. Instead of dead erythrocytes, new, young ones appear, which are formed in the red bone marrow from its stem cells.

Each erythrocyte has the shape of a disk concave on both sides, 7–8 µm in diameter and 1–2 µm thick. Outside, erythrocytes are covered with a membrane - the plasmalemma, through which gases, water and other elements selectively penetrate. There are no organelles in the cytoplasm of erythrocytes, 34% of its volume is the hemoglobin pigment, the function of which is the transport of oxygen (O2) and carbon dioxide (CO2).

Hemoglobin consists of the protein globin and the non-protein group of heme containing iron. One erythrocyte contains up to 400 million hemoglobin molecules. Hemoglobin carries oxygen from the lungs to organs and tissues. Hemoglobin with oxygen (O2) attached to it has a bright red color and is called oxyhemoglobin. Oxygen molecules are attached to hemoglobin due to the high partial pressure of O2 in the lungs. With low oxygen pressure in tissues, oxygen is detached from hemoglobin and leaves the blood capillaries to the surrounding cells and tissues. Having given up oxygen, the blood is saturated with carbon dioxide, the pressure of which in the tissues is higher than in the blood. Hemoglobin combined with carbon dioxide (CO2) is called carbohemoglobin. In the lungs, carbon dioxide leaves the blood, the hemoglobin of which is again saturated with oxygen.

Hemoglobin readily reacts with carbon monoxide (CO) to form carboxyhemoglobin. The addition of carbon monoxide to hemoglobin occurs many times easier and faster than the addition of oxygen. Therefore, the content of even a small amount of carbon monoxide in the air is quite enough for it to join the hemoglobin of the blood and block the flow of oxygen into the blood. As a result of a lack of oxygen in the body, oxygen starvation occurs (carbon monoxide poisoning) and associated headache, vomiting, dizziness, loss of consciousness and even death.

Leukocytes (“white blood cells”), like erythrocytes, are formed in the bone marrow from its stem cells. Leukocytes have sizes from 6 to 25 microns, they differ in a variety of shapes, their mobility, and functions. Leukocytes, which are able to exit blood vessels into tissues and return back, participate in the body's defense reactions, they are able to capture and absorb foreign particles, cell decay products, microorganisms, and digest them. In a healthy person, in 1 µl of blood, there are from 3500 to 9000 leukocytes (3.5-9) x 109 / l. The number of leukocytes fluctuates during the day, their number increases after eating, during physical work, with strong emotions. In the morning, the number of leukocytes in the blood is reduced.

According to the composition of the cytoplasm, the shape of the nucleus, granular leukocytes (granulocytes) and non-granular leukocytes (agranulocytes) are distinguished. Granular leukocytes have a large number of small granules in the cytoplasm, stained with various dyes. In relation to the granules to dyes, eosinophilic leukocytes (eosinophils) are isolated - the granules are stained with eosin in a bright pink color, basophilic leukocytes (basophils) - the granules are stained with basic dyes (azure) in dark blue or purple and neutrophilic leukocytes (neutrophils ), which contain purplish-pink granules.

Non-granular leukocytes include monocytes with a diameter of up to 18-20 microns. These are large cells containing nuclei of various shapes: bean-shaped, lobulated, horseshoe-shaped. The cytoplasm of monocytes is stained in a bluish-gray color. Monocytes of bone marrow origin are precursors of tissue macrophages. The residence time of monocytes in the blood is from 36 to 104 hours.

The leukocyte group of blood cells also includes the working cells of the immune system - lymphocytes (see "Immune system").

In a healthy person, the blood contains 60-70% neutrophils, 1-4% eosinophils, 0-0.5% basophils, 6-8% monocytes. The number of lymphocytes is 25-30% of all "white" blood cells. In inflammatory diseases, the number of leukocytes in the blood (and lymphocytes too) increases. This phenomenon is called leukocytosis.

In allergic diseases, the number of eosinophils increases, in some other diseases - neutrophils or basophils. When the function of the bone marrow is suppressed, for example, under the action of radiation, large doses of X-rays, or the action of toxic substances, the number of leukocytes in the blood decreases. This condition is called leukemia.

Platelets (platelets), having a size of 2-3 microns, are present in 1 microliter of blood in the amount of 250,000-350,000 (300x109 / l). Muscular work, food intake increase the number of platelets in the blood. Thrombocytes do not have a nucleus. These are spherical plates capable of sticking to foreign surfaces, sticking them together. At the same time, platelets secrete substances that promote blood clotting. The life span of platelets is up to 5-8 days.

Protective functions of blood Blood clotting. Blood flowing through intact blood vessels remains liquid. When a vessel is damaged, the blood flowing out of it coagulates quite quickly (after 3-4 minutes), and after 5-6 minutes it turns into a dense clot. This important property of blood coagulation protects the body from blood loss. Coagulation is associated with the conversion of the soluble fibrinogen protein in the blood plasma into insoluble fibrin. The fibrin protein falls out in the form of a network of thin filaments, in the loops of which blood cells linger. This is how a thrombus is formed.

The process of blood coagulation proceeds with the participation of substances released during the destruction of platelets and tissue damage. A protein is released from damaged platelets and tissue cells, which, interacting with blood plasma proteins, is converted into active thromboplastin. For the formation of thromboplastin, the presence in the blood, in particular, of an antihemolytic factor, is necessary. If there is no antihemolytic factor in the blood or it is low, then the blood clotting is low, the blood does not clot. This condition is called hemophilia. Further, with the participation of the formed thromboplastin, the blood plasma protein prothrombin is converted into the active enzyme thrombin. When exposed to the formed thrombin, the fibrinogen protein dissolved in plasma is converted into insoluble fibrin. In a network of these fibrin protein fibers, blood cells settle.

To prevent blood clotting in the blood vessels, the body has an anti-coagulant system. Heparin is formed in the liver and lungs, which prevents blood clotting by turning thrombin into an inactive state.

Blood groups. Blood transfusion. In case of blood loss as a result of an injury and during some operations, a transfusion of another person's blood (donated blood) to a person (called a recipient) is practiced. It is important that the donor blood is compatible with the blood of the recipient. The fact is that when mixing blood from different individuals, erythrocytes that find themselves in the blood plasma of another person can stick together (agglutinate) and then collapse (hemolyze). Hemolysis is the process of destruction of the cytolemma of erythrocytes and the release of hemoglobin from them into the surrounding blood plasma. Hemolysis of erythrocytes (blood) can occur when incompatible blood groups are mixed or when a hypotonic solution is introduced into the blood, under the action of chemical toxic substances - ammonia, gasoline, chloroform and others, as well as as a result of the action of the venom of some snakes.

The fact is that in the blood of each person there are special proteins that are able to interact with the same blood proteins of another person. In erythrocytes, such protein substances are called agglutinogens, denoted by capital letters A and B. Blood plasma also contains protein substances called agglutinins a (alpha) and p (beta). Blood coagulation (agglutination and hemolysis of erythrocytes) occurs when agglutinogen and agglutinin of the same name (A and a;

B and r). Taking into account the presence of agglutinogens and agglutinins, human blood is divided into four groups (Table 3).

Table Classification of human blood groups As shown in Table 3, in the first (I) blood group, in its plasma, both agglutinins (a and -

TEACHER EDUCATION

M. R. SAPIN, V. I. SIVOGLAZOV

ANATOMY

AND PHYSIOLOGY

HUMAN

(WITH AGE PECULIARITIES

CHILDREN'S ORGANISM)

Ministry of Education of the Russian Federation

as a teaching aid for students

secondary pedagogical educational institutions 3rd edition, stereotypical Moscow

ACADEMA

2002 UDC611/612(075.32) BBC28.86ya722 C 19 Publishing program "Textbooks and teaching aids for teacher training schools and colleges"

Program leader Z.A. Nefedova Reviewers:

head Department of Anatomy and Sports Morphology of the Academy of Physical Culture, Corresponding Member of the Russian Academy of Medical Sciences, Professor B.A. Nikityuk;

head Department of Human Anatomy of the Moscow Medical Dental Institute, Doctor of Medical Sciences, Professor L. L. Kolesnikov Sapin M.R., Sivoglazov V.I.

ISBN 5-7695-0904-X The manual provides basic information on human anatomy and physiology from the standpoint of modern medical science.

The age-related changes occurring in the child's body are especially highlighted.

The book is written in an accessible form. The texts are provided with drawings, diagrams, tables that facilitate easy assimilation of the material.

Students of pedagogical universities can also use the textbook.

UDC 611/612(075.32) BBK28.86ya © Sapin M.R., Sivoglazov V.I., ISBN 5-7695-0904-X © Publishing Center "Academy",

INTRODUCTION

Anatomy and physiology are the most important sciences about the structure and functions of the human body. Every physician, every biologist should know how a person works, how his organs “work”, especially since both anatomy and physiology are biological sciences.

Man, as a representative of the animal world, obeys the biological laws inherent in all living beings. At the same time, man differs from animals not only in his structure. He is distinguished by developed thinking, intelligence, the presence of articulate speech, social conditions of life and social relationships. Labor and the social environment had a great influence on the biological characteristics of a person, significantly changed them.

Much attention in anatomy and physiology is paid to childhood, during the period of rapid growth and development of the human body, as well as to old and senile age, when involutive processes are manifested, often contributing to various diseases.

Anatomy studies the structure, and physiology - the functions of a practically healthy, "normal" person. At the same time, among the medical sciences there are pathological anatomy and pathological physiology (from the Greek pathia - disease, suffering), which examine organs altered by diseases and physiological processes disturbed.

Normal can be considered such a structure of the human body, its organs, when their functions are not violated. However, there is a concept of individual variability (variants of the norm), when body weight, height, physique, metabolic rate deviate in one direction or another from the most common indicators.

Anatomy and physiology are constantly updated with new scientific facts, reveal new patterns.

Human anatomy, in turn, serves as the basis for a number of other biological sciences. This is anthropology (from the Greek anthropos - man) - the science of man, his origin, human races, their distribution over the territories of the Earth; histology (from the Greek histos - tissue) - the study of the tissues of the human body from which organs are built; cytology (from the Greek kytus - cell) - the science of the structure and activity of various types of cells; embryology (from the Greek embryon - embryo) - a science that studies the development of humans (and animals) in the prenatal period of life, education, the formation of individual organs and the body as a whole. All these sciences are part of the general doctrine of man. However, having appeared in the depths of anatomy, they separated from it at different times due to the emergence of new research methods, the development of new scientific directions.

The endoscopy method (from the Greek endo - inside, scopia - at the end of the word - examination with mirrors) makes it possible to examine hollow internal organs from the inside with the help of tubes and optical systems. Anatomy and physiology use various experimental methods, which makes it possible to investigate and understand the mechanisms of changes and adaptive processes in organs and tissues, to study the reserve possibilities of their vital activity.

MAIN STAGES OF HUMAN DEVELOPMENT

Individual development, or development in ontogenesis, occurs in all periods of life - from conception to death.

In human ontogenesis (from the Greek on, genus case ontos - existing) there are two periods: before birth (intrauterine) and after birth (extrauterine). In the intrauterine period, from conception to birth, the embryo (embryo) develops in the mother's body. During the first weeks, the main processes of the formation of organs and body parts take place. This period is called the embryonic, and the body of the future person is the embryo (embryo). Starting from the 9th week of development, when the main external human features have already begun to be identified, the body is called the fetus, and the period is fetal.

After fertilization (fusion of sperm and egg), which usually occurs in the fallopian tube, a unicellular embryo is formed - a zygote. Within 3 days, the zygote splits (divides). As a result, a multicellular vesicle is formed - a blastula with a cavity inside.

The walls of this vesicle are formed by two types of cells:

large and small. From small cells, the walls of the vesicle are formed - the trophoblast, from which the outer layer of the shells of the embryo is subsequently created. Larger cells (blastomeres) form clusters - the embryoblast (embryo rudiment), which is located inside the trophoblast (Fig. 1). From this accumulation ("nodule") the embryo and adjacent extraembryonic structures (except for the trophoblast) develop. The embryo, which looks like a bubble, on the 6-7th day of pregnancy is introduced (implanted) into the uterine mucosa. In the second week of development, the embryo (embryoblast) is divided into two plates Fig. 1. The position of the embryo and embryonic membranes at different stages of human development:

A - 2-3 weeks; B - 4 weeks; 1 - amnion cavity, 2 - body of the embryo, 3 - yolk sac, 4 - trophoblast; B - 6 weeks; D - fetus 4-5 months:

1 - body of the embryo (fetus), 2 - amnion, 3 - yolk sac, 4 - chorion, 5 - umbilical cord. One plate adjacent to the trophoblast is called the outer germ layer (ectoderm).

The inner plate, facing the cavity of the vesicle, makes up the inner germ layer (endoderm).

The edges of the inner germ layer grow to the sides, bend and form a vitelline vesicle. The outer germ layer (ectoderm) forms the amniotic sac. In the cavity of the trophoblast around the vitelline and amniotic vesicles, cells of the extraembryonic mesoderm, the embryonic connective tissue, are loosely located. At the point of contact between the vitelline and amniotic vesicles, a two-layer plate is formed - the germinal shield. That plate, which is adjacent to the amniotic vesicle, forms the outer part of the germinal shield (ectoderm). The plate of the germinal shield, which is adjacent to the yolk vesicle, is the germinal (intestinal) endoderm. From it develop the epithelial cover of the mucous membrane of the digestive organs (alimentary tract) and the respiratory tract, as well as the digestive and some other glands, including the liver and pancreas.

On the 3rd week of pregnancy (from the 15th-17th day of embryogenesis), the embryo acquires a three-layer structure, its axial organs develop. The cells of the outer (ectodermal) plate of the germinal shield are displaced towards its posterior end. As a result, a thickening is formed at the ectodermal plate - a primary strip oriented anteriorly. The anterior (cranial) part of the primary strip has a slight elevation - the primary (Hensen's) nodule. The cells of the outer nodule (ectoderm), lying in front of the primary vesicle, plunge into the gap between the outer (ectodermal) and inner (endodermal) plates and form the chordal (head) process, from which the dorsal string is formed - the chord. The cells of the primary streak, growing in both directions between the outer and inner plates of the germinal shield and on the sides of the chord, form the middle germ layer - the mesoderm. The embryo becomes three-layered. At the 3rd week of development, the neural tube begins to form from the ectoderm.

From the back of the endodermal plate, the allantois protrudes into the extraembryonic mesoderm (the so-called amniotic stalk). In the course of the allantois from the embryo through the amniotic stalk to the villi of the chorion, blood (umbilical) vessels also sprout, which later form the basis of the umbilical cord.

At the 3-4th week of development, the body of the embryo (embryonic shield) gradually separates from extraembryonic organs (yolk sac, allantois, amniotic leg). The embryonic shield is bent, a deep furrow is formed on its sides - the trunk fold. This fold delimits the edges of the germ layer from the amnion. The body of the embryo from a flat shield turns into a three-dimensional one, the ectoderm covers the embryo from all sides.

The endoderm, which is inside the body of the embryo, rolls up into a tube and forms the rudiment of the future intestine.

The narrow opening connecting the embryonic intestine with the yolk sac later turns into the umbilical ring. From the endoderm, the epithelium and glands of the gastrointestinal tract and respiratory tract are formed. From the ectoderm, the nervous system, the epidermis of the skin and its derivatives, the epithelial lining of the oral cavity, the anal part of the rectum, the vagina and other organs are formed.

At the end of the 3rd week of development, mesoderm differentiation begins. The mesenchyme arises from the mesoderm. The dorsal part of the mesoderm, located on the sides of the chord, is subdivided into 43-44 pairs of body segments - somites. Three parts are distinguished in somites. Anterior medial - sclerotome, from which the bones and cartilages of the skeleton develop. Lateral to the sclerotome is the myotome, from which the striated skeletal muscles are formed.

Outside lies the dermatome, from which the skin itself arises.

From the anterior (ventral) non-segmented part of the mesoderm (splanchnotome), two plates are formed. One of them (medial, visceral) is adjacent to the primary intestine and is called splanchnopleura. The other (lateral, external) is adjacent to the wall of the body of the embryo, to the ectoderm and is called the somatopleura. From these plates, the peritoneum, pleura (serous membranes) develop, and the space between the plates turns into the peritoneal, pleural and pericardial cavities. From the mesenchyme of the ventral non-segmented mesoderm (splanchnotome), unstriated smooth muscle tissue, connective tissue, blood and lymphatic vessels, and blood cells are formed. The heart, kidneys, adrenal cortex, gonads, and other structures also develop from the mesenchyme of splanchnotomes.

By the end of the first month of intrauterine development, the laying of the main organs of the embryo, which has a length of 6.5 mm, is completed.

On the 5th-8th week, the fin-like rudiments of the upper and then the lower extremities appear in the embryo in the form of skin folds, into which the bones, muscles, vessels and nerves later grow.

During the entire fetal period, growth and further development of already formed organs and tissues occurs. The differentiation of the external genitalia begins. Nails are laid on the fingers. At the end of the 5th month, eyebrows and eyelashes appear. At the 7th month, the eyelids open, fat begins to accumulate in the subcutaneous tissue.

After birth, the child grows rapidly, the weight and length of his body, and the surface area of the body increase (Table 1).

Human growth continues during the first 20 years of his life. In men, the increase in body length ends, as a rule, at 20-22 years old, in women - at 18-20 years old. Then, up to 60-65 years, the body length almost does not change. However, in the elderly and senile age (after 60-70 years), due to an increase in the bends of the spinal column and a change in body posture, thinning of the intervertebral discs, flattening of the arches of the foot, the body length decreases by 1-1.5 mm annually.

During the first year of life after birth, the height of the child increases by 21-25 cm.

Length, body weight and body surface area in different age periods of postnatal ontogenesis Parameters Newborn Age periods / sex (m-male, female-female) Body weight, kg body weight, body cm, cm Notes e: digital data taken from the books “Man. Morphobiological Data" (1977), "Human Morphology" ed. B.A. Nikityuk, V.P. Chtetsova (1990).

At the same time, in girls, the most intensive growth is observed at the age of 10 to 13 years, and in boys - in adolescence. Then growth slows down.

Body weight doubles by 5-6 months after birth.

Stable body weight usually persists until 40-46 years.

It is considered important and physiologically justified to maintain body weight until the end of life within the figures of 19-20 years of age.

After birth, during the period of continuing growth of a person, each age has its own morphological and functional features.

The spine is devoid of bends, the cape is only slightly pronounced. The bones that form the pelvic bone are not fused together. The internal organs are relatively larger than those of an adult. So, for example, the mass of the liver Fig. 2. Changes in the proportions of body parts in the process of growth.

KM - the middle line. The numbers at the top show what part of the body the head is. The divisions marked with numbers on the right are the correspondence of the body parts of children and adults; the numbers below - the age of a newborn child is "/20 of body weight, while in an adult it is "/50. The length of the intestine is 2 times the length of the body, in an adult - 4-4 times. The mass of the brain of a newborn is 13-14% of body weight, and in an adult, only about 2%. The adrenal glands and thymus are large.

In infancy (10 days - 1 year), the child's body grows most rapidly. From about 6 months, the eruption of milk teeth begins. During the first year of life, the sizes of a number of organs and systems reach the sizes characteristic of an adult (eye, inner ear, central nervous system). During the first years of life, the musculoskeletal system, digestive, and respiratory systems grow and develop rapidly.

The child begins to navigate in space. During the 2nd-3rd years of life, the growth in length prevails over the increase in body weight. At the end of the period, the eruption of permanent teeth begins. In connection with the rapid development of the brain, whose mass reaches 1100–1200 g by the end of the period, mental abilities and causal thinking develop rapidly, the ability to recognize, orientation in time, in days of the week is retained for a long time.

In early and first childhood (4-7 years), sexual differences (except for primary sexual characteristics) are almost not expressed. In the period of second childhood (8-12 years), growth in width again prevails, but at this time puberty begins, and by at the end of the period, the growth of the body in length increases, the rate of which is greater in girls.

The mental development of children is progressing. Orientation towards months and calendar days develops.

Puberty begins, earlier in girls, which is associated with increased secretion of female sex hormones. In girls at the age of 8-9, the pelvis begins to expand and the hips become rounded, the secretion of the sebaceous glands increases, and pubic hair develops. In boys, at the age of 10-11, the growth of the larynx, testicles and penis begins, which by the age of 12 increases by 0.5-0.7 cm.

In adolescence (12-16 years), the genital organs grow and develop rapidly, secondary sexual characteristics intensify. In girls, the amount of hair on the skin of the pubic region increases, hair appears in the armpits, the size of the genital organs and mammary glands increase, the alkaline reaction of the vaginal secretion becomes acidic, menstruation appears, and the size of the pelvis increases. In boys, the testicles and penis rapidly increase, at first the pubic hair develops according to the female type, the mammary glands swell. By the end of adolescence (15-16 years), hair growth begins on the face, body, in the armpits, and on the pubis - according to the male type, the skin of the scrotum is pigmented, the genitals increase even more, the first ejaculations occur (involuntary ejaculations).

In adolescence, mechanical and verbal-logical memory develops.

The structure of the body in adulthood (22-60 years) changes little, and in the elderly (61-74 years) and senile (75 years) there are changes characteristic of these ages, which are studied by a special science - gerontology (from the Greek geron - old man ). The time limits of aging vary widely in different individuals. In old age, there is a decrease in the adaptive capabilities of the body, a change in the morphological and functional indicators of all apparatuses and organ systems, among which the most important role belongs to the immune, nervous and circulatory systems.

An active lifestyle and regular exercise slow down the aging process. However, this is possible within the limits due to hereditary factors.

Sexual characteristics distinguish men from women (Table 1).

2). They are divided into primary (genital organs) and secondary (development of pubic hair, development of mammary glands, voice changes, etc.).

In anatomy, there are concepts about body types. Physique is determined by genetic (hereditary) factors, the influence of the external environment, social conditions. There are three types of human physique: mesomorphic, brachymorphic and dolichomorphic. With a mesomorphic (from the Greek mesos - average, morphe - shape, appearance) body type (normosthenics), anatomical features Some gender differences in men (m) and women (g) sizes) body structure fiber approaches the average norm (taking into account age, gender). Persons of a brachymorphic (from the Greek brachys - short) body type (hypersthenics) are short in stature, have a wide body, and tend to be overweight. Their diaphragm is located high, the heart lies on it almost transversely, the lungs are short, the muscles are well developed. Individuals with a dolichomorphic body type (from the Greek dolichos - long) are tall and have long limbs. The muscles are poorly developed. The diaphragm is low, the lungs are long, the heart is located almost vertically.

Human anatomy studies the structure of a normal (average) person, therefore such anatomy is called normal. For the convenience of studying the position of organs, body parts, three mutually perpendicular planes are used. The sagittal plane (from the Greek sagitta - arrow) vertically cuts the body from front to back. The frontal plane (from Latin from - forehead) is located perpendicular to the sagittal, oriented from right to left.

The horizontal plane occupies a perpendicular position with respect to the first two, it separates the upper body from the lower.

In anatomy, the terms middle (medial, lying closer to the median plane) and lateral (lateral, located at a distance from the median plane) are distinguished. To designate parts of the upper and lower extremities, the concepts of proximal - located closer to the beginning of the limb, and distal - located further from the body are used.

When studying anatomy, terms such as right and left, large and small, superficial and deep are used.

When determining the position of organs in a living person, the projections of their boundaries on the surface of the body use vertical lines drawn through certain points. The anterior median line is drawn along the middle of the anterior surface of the body. The posterior midline runs along the spinous processes of the vertebrae. Both of these lines connect the right half of the body with the left. The right and left sternal (oblosternal) lines run along the corresponding edges of the sternum. The midclavicular line runs vertically through the middle of the clavicle. Axillary (anterior, middle and posterior) lines are drawn through the middle and the corresponding edges of the axillary fossa. The scapular line passes through the lower angle of the scapula. The paravertebral line is drawn next to the spine through the costotransverse joints.

1. What is a zygote? What and where is it formed from?

2. What embryonic structures form the ectoderm and endoderm? Which organs of them develop in the future?

3. When and from what is the middle germ layer formed?

4. What parts are isolated from somites and from splanchnotome?

5. What factors influence the development of the embryo?

6. What anatomical features are typical for a newborn?

7. What systems and apparatuses of organs grow and develop faster in children, adolescents, in adolescence?

8. Name the body types you know and their distinctive features.

STRUCTURE OF THE HUMAN BODY

CELLS

A cell is an elementary, universal unit of living matter. The cell has an ordered structure, is able to receive energy from outside and use it to perform the functions inherent in each cell. Cells actively respond to external influences (irritations), participate in metabolism, have the ability to grow, regenerate, reproduce, transfer genetic information, and adapt to environmental conditions.

Cells in the human body are diverse in shape, they can be flat, round, ovoid, spindle-shaped, cubic, process. The shape of cells is determined by their position in the body and function.

Cell sizes vary from a few micrometers (for example, a small lymphocyte) to 200 microns (an egg).

The intercellular substance is a product of the vital activity of cells and consists of the main substance and various connective tissue fibers located in it.

Despite the great diversity, all cells have common structural features and consist of a nucleus and cytoplasm enclosed in a cell membrane - the cytolemma (Fig. 3). The cell membrane, or cell membrane (cytolemma, plasmalemma), delimits the cell from the external environment. The thickness of the cytolemma is 9-10 nm (1 nanometer is equal to 10~8 m or 0.002 µm). The cytolemma is built from protein and lipid molecules and is a three-layer structure, the outer surface of which is covered with fine fibrillar glycocalyx. The glycocalyx contains various carbohydrates that form long branching chains of polysaccharides. These polysaccharides are associated with protein molecules that make up the cytolemma. In the cytolemma, the outer and inner electron-dense lipid layers (plates) have a thickness of about 2.5 nm, and the middle electron-transparent layer (hydrophobic zone of lipid molecules) is about 3 nm. The bilipid layer of the cytolemma contains protein molecules, some of which pass through the entire thickness of the cell membrane.

The cytolemma not only separates the cell from the external environment. It protects the cell, performs receptor functions (perceives the effects of the external environment for the cell), and a transport function. Through the cytolemma, various substances (water, low molecular weight compounds, ions) are transferred both inside the cell and out of the cell. With the expenditure of energy (ATP splitting), various organic substances (amino acids, sugars, etc.) are actively transported through the cytolemma.

The cytolemma also forms intercellular connections (contacts) with neighboring cells. Contacts can be simple or complex. Simple connections are in the form of a jagged suture, when the outgrowths (teeth) of the cytolemma of one cell are introduced between the outgrowths of a neighboring cell. Between the cytolemmas of neighboring cells there is an intercellular gap 15–20 nm wide. Complex contacts are formed by Fig. 3. Scheme of the ultramicroscopic structure of the cell: 1 - cytolemma (plasma membrane), 2 - pinocytic vesicles, 3 - centrosome (cell center, cytocenter), 4 - hyaloplasm, 5 - endoplasmic reticulum (a - membranes of the endoplasmic reticulum, b - ribosomes), 6 - nucleus, 7 - connection of the perinuclear space with the cavities of the endoplasmic reticulum, 8 - nuclear pores, 9 - nucleolus, 10 - intracellular reticular apparatus (Golgi complex), 11 - secretory vacuoles, 12 - mitochondria, 13 - lysosomes, 14 - three consecutive stages of phagocytosis, 15 - the connection of the cell membrane (cytolemma) with the membranes of the endoplasmic reticulum or the cell membranes of neighboring cells tightly adjacent to each other (tight junctions), or the presence of a fine fibrillar substance (desmosome) between neighboring cells. Conductive junctions include synapses and gap junctions - nexuses. Synapses between the cytolemma of neighboring cells have a gap through which transport occurs (transfer of excitation or inhibition) in only one direction. In nexuses, the slit-like space between neighboring cytolemmas is divided into separate short sections by special protein structures.

The cytoplasm is heterogeneous in composition, it includes hyaloplasm and organelles and inclusions in it.

Hyaloplasm (from the Greek hyalinos - transparent) forms the matrix of the cytoplasm, its internal environment. Outside, it is delimited by a cell membrane - the cytolemma. Hyaloplasm has the appearance of a homogeneous substance, is a complex colloidal system consisting of proteins, nucleic acids, polysaccharides, enzymes and other substances.

The most important role of the hyaloplasm is to unite all intracellular structures and to ensure their chemical interaction with each other. In the hyaloplasm, proteins are synthesized that are necessary for the life and functions of the cell. Glycogen, fatty inclusions are deposited in the hyaloplasm, an energy reserve is contained - molecules of adenosine triphosphoric acid (ATP).

In the hyaloplasm there are general-purpose organelles that are present in all cells, as well as non-permanent structures - cytoplasmic inclusions.

The organelles include mitochondria, internal reticulum (Golgi complex), cytocenter (cell center), granular and non-granular endoplasmic reticulum, ribosomes, lysosomes. Inclusions include glycogen, proteins, fats, vitamins, pigment substances and other structures.

Membrane organelles are closed single or interconnected microscopic cavities separated by a membrane from the surrounding hyaloplasm. Membrane organelles are mitochondria, internal reticulum (Golgi complex), endoplasmic reticulum, lysosomes, peroxisomes. The endoplasmic reticulum is divided into granular and non-granular. Both of them are formed by cisterns, vesicles and channels, which are limited by a membrane about 6-7 nm thick. The endoplasmic reticulum, to the membranes of which ribosomes are attached, is called the granular (rough) endoplasmic reticulum. If there are no ribosomes on the surface of the membranes, this is a smooth endoplasmic reticulum.

The membranes of the endoplasmic reticulum are involved in the transport of substances in the cell. Protein synthesis is carried out on the ribosomes of the granular endoplasmic reticulum, glycogen and lipids are synthesized on the membranes of the smooth endoplasmic reticulum.

The internal mesh apparatus (Golgi complex) is formed by membranes of tightly lying flat cisterns and numerous small vesicles (vesicles) located along their periphery. The places of accumulation of these membranes are called dictyosomes. One dictyosome includes 5 flat membranous cisterns separated by layers of hyaloplasm. The membranes of the internal reticular apparatus perform the functions of accumulation, chemical rearrangement of substances that are synthesized by the endoplasmic reticulum.

In the tanks of the Golgi complex, polysaccharides are synthesized, which form a complex with proteins. The Golgi complex is involved in the excretion of synthesized substances outside the cell and is the source of the formation of cellular lysosomes.

Mitochondria have a smooth outer membrane and an inner membrane with protrusions in the form of ridges (cristae) inside the mitochondria. Folding of the inner mitochondrial membrane significantly increases its inner surface. The outer membrane of the mitochondria is separated from the inner one by a narrow intermembrane space. The cavity of the mitochondria between the cristae is filled with a matrix having a fine-grained structure. It consists of DNA molecules (deoxyribonucleic acid) and mitochondrial ribosomes. The diameter of mitochondria averages 0.5 microns, and the length reaches 7-10 microns. The main function of mitochondria is the oxidation of organic compounds and the use of the released energy for the synthesis of ATP molecules.

Lysosomes are spherical structures 0.2-0.4 microns in size, limited by a membrane. The presence of hydrolytic enzymes (hydrolases) in lysosomes that break down various biopolymers indicates their participation in the processes of intracellular digestion.

Along with single ribosomes, cells have groups of ribosomes (polysomes, polyribosomes).

Microtubules are located in the cytoplasm of cells. They are hollow cylinders with a diameter of about 24 nm. Microtubules are formed by tubulin proteins.

In the cytoplasm, microtubules form the cytoskeleton and are involved in the motor functions of cells. Microtubules support the shape of cells, promote their oriented movements. Microtubules are part of the centrioles, the spindle of cell division, basal bodies, flagella, cilia.

Centrioles are hollow cylinders with a diameter of about 0.25 µm and a length of up to 0.5 µm. The walls of the centrioles are built of microtubules, which form nine triplets (9*3) connected to each other. Two centrioles lying at right angles to each other form a diplosome. Around the centrioles (diplosomes) there is a centrosphere in the form of a structureless dense rim with radially thin fibrils extending from it.

Centrioles and centrosphere together form the cell center. In preparation for mitotic division, the number of centrioles in the cell doubles.

Microfilaments are thin (5-7 nm) protein filaments located in the form of bundles or layers mainly in the peripheral parts of the cell. The composition of microfilaments includes various contractile proteins: actin, myosin, tropomyosin. Microfilaments perform the musculoskeletal function of cells. Intermediate filaments, or microfibrils, about 10 nm thick, have a different composition in different cells.

Inclusions of the cytoplasm of cells serve as temporary structures, they are formed as a result of the activity of the cell. There are trophic, secretory and pigment inclusions. Trophic inclusions are protein, fat and carbohydrate. They serve as reserves of nutrients, accumulated by the cell. Secretory inclusions are products of the function of glandular cells, contain biologically active substances necessary for the body. Pigmented inclusions are colored substances necessary for the body that accumulate in the cell. The pigment can be of exogenous origin (dyes, etc.) and endogenous (melanin, hemoglobin, bilirubin, lipofuscin).

Cell nucleus. The nucleus is an essential element of the cell, it contains genetic information and regulates protein synthesis. Genetic information is embedded in the molecules of deoxyribonucleic acid (DNA).

The nucleus of a non-dividing cell (interphase) often has a spherical or ovoid shape and consists of chromatin, nucleolus, karyoplasm (nucleoplasm), delimited from the cytoplasm by the nuclear membrane.

The chromatin of the interphase nucleus is a chromosomal material - these are loosened, decondensed chromosomes. Decondensed chromosomes are called euchromatin. Thus, chromosomes in cell nuclei can be in two structural and functional states. In the decondensed form, the chromosomes are in a working, active state. At this time, they are involved in the processes of transcription (reproduction), replication (from Latin replicatio - repetition) of nucleic acids (RNA, DNA). Chromosomes in a condensed state (dense) are inactive, they participate in the distribution and transfer of genetic information to daughter cells during cell division. In the initial phases of mitotic cell division, chromatin condenses to form visible chromosomes. In humans, somatic cells contain 46 chromosomes - 22 pairs of homologous chromosomes and two sex chromosomes. In women, the sex chromosomes are paired (XX chromosomes), in men - unpaired (XY chromosomes).

The nucleolus is a dense, intensely stained formation in the nucleus, round in shape, 1-5 microns in size.

The nucleoplasm, the electron-transparent part of the nucleus, is a colloidal solution of proteins that surrounds the chromatin and nucleolus.

The nuclear envelope (nucleolemma) consists of an outer nuclear membrane and an inner nuclear membrane separated by a perinuclear space. The nuclear membrane has pores in which protein granules and filaments are located (pore complex). Through the nuclear pores, selective transport of proteins occurs, which ensures the passage of macromolecules into the cytoplasm, as well as the exchange of substances between the nucleus and the cytoplasm.

Cell division (cell cycle) The growth of the body, the increase in the number of cells, their reproduction occurs by division. Mitosis and meiosis are the main methods of cell division in the human body. The processes occurring in these methods of cell division proceed in the same way, but they lead to different results. Mitotic cell division leads to an increase in the number of cells, to the growth of the organism. In this way, cell renewal is ensured when they are worn out and die. (Currently, it is known that epidermal cells live 3-7 days, erythrocytes - up to 4 months. Nerve and muscle cells (fibers) live throughout a person's life.) Due to mitotic division, daughter cells receive a set of chromosomes identical to the mother.

Meiosis - is a kind of division, when four daughter nuclei are formed from one, each of which contains half as many chromosomes as in the mother nucleus. During meiosis, two successive (meiotic) cell divisions occur. As a result, a single (haploid) set (In) is formed from a double (diploid) number of chromosomes (2n). Meiosis occurs only during the division of germ cells, while maintaining a constant number of chromosomes, which ensures the transfer of hereditary information from one cell to another. In all cells, during reproduction (division), changes are observed that fit within the framework of the cell cycle.

The cell cycle is the name given to the processes that occur in a cell when preparing a cell for division and during division, as a result of which one cell (mother) is divided into two daughters (Fig. 4). In the cell cycle, the preparation of the cell for division (interphase) and mitosis (the process of cell division) are distinguished.

Mitosis (from the Greek mitos - thread) is the period when the mother cell is divided into two daughter cells.

Mitotic cell division provides a uniform distribution of cell structures, its nuclear substance - chromatin - between two daughter cells. DurationFig. 4. Stages of chromatin condensation with the formation of chromosomes, the formation of a fission spindle and the uniform distribution of mitosis - from 30 minutes to 3 hours. Mitosis is divided into prophase, metaphase, anaphase, telophase.

In prophase, the nucleolus gradually disintegrates, centrioles diverge towards the poles of the cells.

In metaphase, the nuclear membrane is destroyed, the chromosome threads are sent to the poles, maintaining a connection with the equatorial region of the cell. The structures of the endoplasmic reticulum and the Golgi complex disintegrate into small vesicles (vesicles), which, together with mitochondria, are distributed into both halves of the dividing cell. At the end of metaphase, each chromosome begins to split with a longitudinal cleft into two new daughter chromosomes.

In anaphase, the chromosomes separate from each other and diverge towards the poles of the cell at a rate of up to 0.5 µm/min.

In telophase, the chromosomes that have diverged to the poles of the cell decondense, pass into chromatin, and transcription (production) of RNA begins. The nuclear membrane, the nucleolus is formed, the membrane structures of future daughter cells are quickly formed. On the surface of the cell, along its equator, a constriction appears, which deepens, the cell is divided into two daughter cells.

1. Name the structural elements of the cell.

2. What functions does the cell perform?

3. List the membrane and non-membrane cell organelles, name their functions.

4. What elements does the cell nucleus consist of, what functions does it perform?

5. What are the types of cell connections with each other?

6. What is the cell cycle, what periods (phases) are distinguished in it (in this cycle)?

7. What is meiosis, how does it differ from mitosis?

Cells and their derivatives combine to form tissues.

A tissue is a collection of cells and intercellular substance that has developed in the process of evolution and has a common origin, structure and function. According to morphological and physiological characteristics, four types of tissues are distinguished in the human body: epithelial, connective, muscle and nervous.

The epithelium of the epithelial tissue forms the surface layers of the skin, covers the mucous membrane of the hollow internal organs, the surface of the serous membranes, and also forms glands. In this regard, cover epithelium and glandular epithelium are distinguished.

The integumentary epithelium occupies a border position in the body, separating the internal environment from the external one, protects the body from external influences, performs the functions of metabolism between the body and the external environment.

The glandular epithelium forms glands that differ in shape, location and function. Epithelial cells (glandulocytes) of the glands synthesize and secrete substances - secrets involved in various body functions. Therefore, the glandular epithelium is also called the secretory epithelium.

The integumentary epithelium forms a continuous layer consisting of densely arranged cells connected to each other using various types of contacts. Epitheliocytes always lie on a basement membrane rich in carbohydrate-protein-lipid complexes, on which its selective permeability depends. The basement membrane separates the epithelial cells from the underlying connective tissue. The epithelium is abundantly supplied with nerve fibers and receptor endings that transmit signals about various external influences to the central nervous system. The nutrition of the cells of the integumentary epithelium is carried out by diffusion of tissue fluid from the underlying connective tissue.

According to the ratio of epithelial cells to the basement membrane and their position on the free surface of the epithelial layer, single-layer and stratified epithelium are distinguished (Fig. 5). In a single-layer epithelium, all cells lie on the basement membrane, in multilayered epithelium, only the deepest layer is adjacent to the basement membrane.

A single-layered epithelium, in the cells of which the nuclei are located at the same level, is called single-row. The epithelium, the nuclei of which lie at different levels, is called multi-row. Stratified epithelium is non-keratinizing (stratified squamous non-keratinizing), as well as keratinizing (stratified squamous keratinizing), in which superficially located cells become keratinized, turn into horny scales. The transitional epithelium is so named because its structure changes depending on the stretching of the walls of the organ that this epithelium covers (for example, the epithelial lining of the bladder mucosa).

According to the shape, epitheliocytes are divided into flat, cubic and prismatic. In epithelial cells, a basal part is isolated, facing the basement membrane, and an apical part, directed to the surface of the layer of the integumentary epithelium. In the basal part there is a nucleus, in the apical part there are cell organelles, inclusions, including secretory granules in Fig. 5. Scheme of the structure of epithelial tissue:

A - simple squamous epithelium (mesothelium); B - simple cubic epithelium; B - simple columnar epithelium; G - ciliated epithelium; D - transitional epithelium; E - non-keratinized stratified (squamous) squamous epithelium of the glandular epithelium. On the apical part there may be microvilli - outgrowths of the cytoplasm in specialized epithelial cells (ciliated epithelium of the respiratory tract).

Integumentary epithelium in case of damage is able to quickly recover by the mitotic method of cell division. In a single-layer epithelium, all cells have the ability to divide, in a multilayer epithelium, only basally located cells. Epithelial cells, intensively multiplying along the edges of the damage, crawl onto the wound surface, restoring the integrity of the epithelial cover.

Connective tissue is formed by cells and intercellular substance, which always contains a significant amount of connective tissue fibers. Connective tissue, having a different structure, location, performs mechanical functions (support), trophic - nutrition of cells, tissues (blood), protective (mechanical protection and phagocytosis).

In accordance with the peculiarities of the structure and functions of the intercellular substance and cells, the connective tissue proper, as well as skeletal tissues and blood, are isolated.

Fibrous connective tissue, in turn, is divided into loose and dense, and the latter - into unformed and formed. The classification of fibrous connective tissue is based on the principle of the ratio of cells and intercellular, fiber structures, as well as the location of connective tissue fibers.

Loose fibrous connective tissue is present in all organs near the blood and lymphatic vessels, nerves and forms the stroma of many organs (Fig. 6). The main cellular elements of loose fibrous connective tissue are fibroblasts. Intercellular structures are represented by the main substance and collagen (adhesive) and elastic fibers located in it. The main substance is a homogeneous colloidal mass, which consists of acidic and neutral polysaccharides in combination with proteins. These polysaccharides are called glycosaminoglycans, proteoglycans, including hyaluronic acid. The liquid part of the main substance is tissue fluid.

Mechanical, strength properties of connective tissue give collagen and elastic fibers. Collagen protein is the basis of collagen fibers. Each collagen fiber consists of individual collagen fibrils about 7 nm thick. Collagen fibers Fig. 6. The structure of loose fibrous connective tissue:

Elastic fibers determine the elasticity and extensibility of the connective tissue. They consist of amorphous elastin protein and filamentous, branching fibrils.

Connective tissue cells are young functionally active fibroblasts and mature fibrocytes.

Fibroblasts take part in the formation of the intercellular substance and collagen fibers. Fibroblasts have a spindle shape, basophilic cytoplasm, they are capable of reproduction by mitosis. Fibrocytes differ from fibroblasts in the poor development of membrane organelles and low metabolic rate.

The connective tissue contains specialized cells, including blood cells (leukocytes) and the immune system (lymphocytes, plasma cells). Loose connective tissue contains mobile cellular elements - macrophages and mast cells.

Macrophages are actively phagocytic cells, 10-20 microns in size, containing numerous organelles for intracellular digestion and synthesis of various antibacterial substances, having numerous villi on the surface of the cell membrane.

In loose fibrous connective tissue there are also fat cells (adipocytes), pigment cells (pigmentocytes).

Dense fibrous connective tissue consists mainly of fibers, a small number of cells and the main amorphous substance. Allocate dense unformed and dense formed fibrous connective tissue. The first of them (unformed) is formed by numerous fibers of various orientations and has complex systems of intersecting bundles (for example, the reticular layer of the skin). In a dense, formed fibrous connective tissue, the fibers are located in one direction, in accordance with the action of the tension force (muscle tendons, ligaments).

Connective tissue with special properties is represented by reticular, adipose, mucous and pigment tissues.

Reticular connective tissue consists of reticular cells and reticular fibers. Fibers and process reticular cells form a loose network. The reticular tissue forms the stroma of the hematopoietic organs and organs of the immune system and creates a microenvironment for the blood and lymphoid cells developing in them.

Mucous connective tissue in the form of large process cells (mucocytes) and intercellular substance, rich in hyaluronic acid, is present in the umbilical cord, protecting the umbilical blood vessels from compression.

Pigmented connective tissue contains a large number of melanocyte pigment cells (iris, age spots, etc.), in the cytoplasm of which there is melanin pigment.

Skeletal tissues include cartilaginous and bone tissues, which perform mainly supporting, mechanical functions in the body, and also take part in mineral metabolism.

Chondrocytes have a round or oval shape, they are located in special cavities (lacunae), they produce all the components of the intercellular substance. Chondroblasts are young cartilage cells. They actively synthesize the intercellular substance of the cartilage, and are also capable of reproduction. Due to chondroblasts, peripheral (appositional) growth of cartilage occurs.

The layer of connective tissue that covers the surface of the cartilage is called the perichondrium. In the perichondrium, the outer layer is isolated - fibrous, consisting of dense fibrous connective tissue and containing blood vessels and nerves. The inner layer of the perichondrium is chondrogenic, containing chondroblasts and their precursors, prechondroblasts. The perichondrium provides appositional growth of the cartilage, its vessels carry out diffuse nutrition of the cartilage tissue and the removal of metabolic products.

According to the structural features of the intercellular substance, hyaline, elastic and fibrous cartilage are isolated.

Hyaline cartilage is translucent and bluish-white in color. This cartilage is found at the junction of the ribs with the sternum, on the articular surfaces of the bones, at the junction of the epiphysis with the diaphysis in tubular bones, in the skeleton of the larynx, in the walls of the trachea, bronchi.

Fibrous cartilage in the intercellular substance contains a large amount of collagen fibers. Fibrous rings of intervertebral discs, articular discs and menisci are built from fibrous cartilage.

Bone tissue is built from bone cells and intercellular substance containing various salts and connective tissue fibers. The location of bone cells, the orientation of the fibers and the distribution of salts provide bone tissue with hardness and strength. The organic substances of the bone are called ossein (from Latin os - bone). The inorganic substances of the bone are salts of calcium, phosphorus, magnesium, etc. The combination of organic and inorganic substances makes the bone strong and elastic. In childhood, there is more organic matter in the bones than in adults, so bone fractures are rare in children. In elderly, old people, the amount of organic matter in the bones decreases, the bones become more fragile, brittle.

Bone cells are osteocytes, osteoblasts and osteoclasts.

Osteocytes are mature, incapable of division, process bone cells from 22 to 55 microns in length, with a large ovoid nucleus. They are spindle-shaped and lie in bone cavities (lacunae). Bone tubules containing processes of osteocytes depart from these cavities.

Osteoblasts are young bone cells with a rounded nucleus. Osteoblasts are formed due to the germ (deep) layer of the periosteum.

Osteoclasts are large multinucleated cells up to 90 µm in diameter. They are involved in the destruction of bone and calcification of cartilage.

There are two types of bone tissue - lamellar and coarse fibrous. Lamellar (fine fibrous) bone tissue consists of bone plates built from mineralized intercellular substance, bone cells and collagen fibers located in it. Fibers in neighboring plates have different orientations. The compact (dense) and spongy substance of the bones of the skeleton are built from lamellar bone tissue. The compact substance forms the diaphysis (middle part) of tubular bones and the surface plate of their epiphyses (ends), as well as the outer layer of flat and other bones. The spongy substance forms beams (beams) located between the plates of the compact substance in the epiphyses and other bones.

Beams (beams) of the spongy substance are located in different directions, which correspond to the direction of the lines of compression and tension of the bone tissue (Fig. 7).

The inner layer of compact bone substance is formed by the inner surrounding plates. These plates are a product of the bone-forming function of the endosteum - a thin connective tissue membrane covering the inner surface of the bone (the walls of the bone marrow cavity and cells of the spongy substance). The outer layer of compact bone substance is formed by the outer surrounding plates formed by the inner bone-forming layer of the periosteum. The outer layer of the periosteum is coarse fibrous, fibrous. This layer is rich in nerve fibers, blood vessels, which not only nourish the periosteum, but also penetrate into the bone through nutrient holes on the surface of the bone. The periosteum is firmly fused to the bone surface with the help of thin joints. 7. The structure of the tubular bone.

1 - periosteum, 2 - compact bone substance, 3 - layer of outer surrounding plates, 4 - osteons, 5 - layer of inner surrounding plates, 6 - medullary cavity, 7 - bone crossbars of spongy bone 8. Blood cells:

1 - basophilic granulocyte, 2 - acidophilic granulocyte, 3 - segmented neutrophilic granulocyte, 4 - erythrocyte, 5 - monocyte, 6 - platelets, 7 - lymphocyte of filamentous fibers (Sharpeev's), penetrating from the periosteum into the bone.

Blood is a type of connective tissue that has a liquid intercellular substance - plasma, in which there are cellular elements - erythrocytes and other cells (Fig. 8). The function of blood is to carry oxygen and nutrients to organs and tissues and remove metabolic products from them.

Blood plasma proteins are involved in the processes of blood coagulation, maintain the constancy of its reaction (pH), contain immunoglobulins involved in the body's defense reactions, ensure the viscosity of the blood, the constancy of its pressure in the vessels, and prevent erythrocyte sedimentation.

The content of glucose in the blood of a healthy person is 80-120 mg% (4.44-6.66 mmol / l). A sharp decrease in the amount of glucose in the blood (up to 2.22 mmol / l) leads to a sharp increase in the excitability of brain cells. The person may have seizures. A further decrease in blood glucose leads to impaired breathing, circulation, loss of consciousness and even death.

The mineral substances of blood plasma are NaCl, KC1, CaC12, NaHCO2, NaH2PO4 and other salts, as well as Na, Ca, K ions. The constancy of the ionic composition of the blood ensures the stability of the osmotic pressure and the preservation of the volume of fluid in the blood and cells of the body.

More complex solutions containing a set of salts necessary for the body are called not only isotonic, but also isoionic. Apply blood-substituting solutions containing not only salts, but also proteins, glucose.

In a hypertonic solution with a high salt concentration and high osmotic pressure, water leaves the red blood cells and they shrivel.

The formed elements (cells) of the blood include erythrocytes, leukocytes, platelets (platelets).

Erythrocytes (red blood cells) are nuclear-free cells that cannot divide. The number of red blood cells in 1 µl of blood in adult men ranges from 3.9 to 5.5 million (5.0 * 10 12 / l), in women - from 3 to 4.9 million (4.5 x 10 " 2 / l).In some diseases, as well as severe blood loss, the number of red blood cells decreases.At the same time, the hemoglobin content in the blood decreases.This condition is called anemia (anemia).

In a healthy person, the lifespan of red blood cells is up to 120 days, and then they die, are destroyed in the spleen. Within 1 second, approximately 10-15 million red blood cells die. Instead of dead red blood cells, new, young ones appear, which are formed in the red bone marrow from its stem cells.

Each erythrocyte has the shape of a disc concave on both sides with a diameter of 7-8 microns, a thickness of 1-2 microns. Outside, erythrocytes are covered with a membrane - the plasmalemma, through which gases, water and other elements selectively penetrate. There are no organelles in the cytoplasm of erythrocytes, 34% of its volume is the hemoglobin pigment, the function of which is the transport of oxygen (O2) and carbon dioxide (CO2).

Hemoglobin consists of the protein globin and a non-protein heme group containing iron. There are up to 400 million hemoglobin molecules in one erythrocyte. Hemoglobin carries oxygen from the lungs to organs and tissues. Hemoglobin with oxygen (O2) attached to it has a bright red color and is called oxyhemoglobin. Oxygen molecules are attached to hemoglobin due to the high partial pressure of O2 in the lungs. With low oxygen pressure in the tissues, oxygen is detached from hemoglobin and leaves the blood capillaries to the surrounding cells and tissues. Having given up oxygen, the blood is saturated with carbon dioxide, the pressure of which in the tissues is higher than in the blood. Hemoglobin combined with carbon dioxide (CO2) is called carbohemoglobin. In the lungs, carbon dioxide leaves the blood, the hemoglobin of which is again saturated with oxygen.

Hemoglobin readily combines with carbon monoxide (CO) to form carboxyhemoglobin. The addition of carbon monoxide to hemoglobin occurs many times easier, faster than the addition of oxygen. Therefore, the content of even a small amount of carbon monoxide in the air is quite enough for it to join the hemoglobin of the blood and block the flow of oxygen into the blood. As a result of a lack of oxygen in the body, oxygen starvation occurs (carbon monoxide poisoning) and associated headache, vomiting, dizziness, loss of consciousness and even death.

Leukocytes (“white blood cells”), like red blood cells, are formed in the bone marrow from its stem cells. Leukocytes have sizes from 6 to 25 microns, they differ in a variety of shapes, their mobility, and functions. Leukocytes, which are able to exit blood vessels into tissues and return back, are involved in the protective reactions of the body, they are able to capture and absorb foreign particles, cell decay products, microorganisms, and digest them. In a healthy person, in 1 µl of blood, there are from 3500 to 9000 leukocytes (3.5-9) x 109 / l. The number of leukocytes fluctuates during the day, their number increases after eating, during physical work, with strong emotions. In the morning, the number of leukocytes in the blood is reduced.

Non-granular leukocytes include monocytes with a diameter of up to 18-20 microns. These are large cells containing nuclei of various shapes: bean-shaped, lobed, horseshoe-shaped. The cytoplasm of monocytes is stained in a bluish-gray color. Monocytes of bone marrow origin are precursors of tissue macrophages. The residence time of monocytes in the blood is from 36 to 104 hours.

The leukocyte group of blood cells also includes the working cells of the immune system - lymphocytes (see "Immune system").

Platelets (platelets), having a size of 2-3 microns, are present in 1 microliter of blood in the amount of 250,000-350,000 (300x109 / l). Muscular work, food intake increase the number of platelets in the blood. Platelets do not have a nucleus. These are spherical plates capable of sticking to foreign surfaces, sticking them together. In this case, platelets secrete substances that promote blood clotting. The life span of platelets is up to 5-8 days.

Protective functions of blood Blood clotting. Blood flowing through intact blood vessels remains liquid. If the vessel is damaged, the blood flowing from it coagulates quite quickly (after 3-4 minutes), and after 5-6 minutes it turns into a dense clot. This important property of blood clotting protects the body from blood loss. Coagulation is associated with the transformation of the soluble fibrinogen protein in the blood plasma into insoluble fibrin. Fibrin protein falls out in the form of a network of thin threads, in the loops of which blood cells linger. This is how a thrombus is formed.

To prevent blood clotting in the blood vessels, the body has an anti-clotting system. Heparin is formed in the liver and lungs, which prevents blood clotting by turning thrombin into an inactive state.

Blood groups. Blood transfusion. With blood loss as a result of an injury and during some operations, a transfusion of a person (called a recipient) of the blood of another person (donor blood) is practiced. It is important that the donor blood is compatible with the blood of the recipient. The fact is that when mixing blood from different individuals, red blood cells that find themselves in the blood plasma of another person can stick together (agglutinate) and then collapse (hemolyze). Hemolysis is the process of destruction of the cytolemma of erythrocytes and the release of hemoglobin from them into the surrounding blood plasma. Hemolysis of erythrocytes (blood) can occur when incompatible blood groups are mixed or when a hypotonic solution is introduced into the blood, under the action of chemical toxic substances - ammonia, gasoline, chloroform and others, as well as as a result of the action of the venom of some snakes.

The fact is that in the blood of each person there are special proteins that are able to interact with the same blood proteins of another person. In erythrocytes, such protein substances are called agglutinogens, denoted by capital letters A and B. Blood plasma also contains protein substances called agglutinins a (alpha) and p (beta). Blood coagulation (agglutination and hemolysis of erythrocytes) occurs if agglutinogen and agglutinin of the same name are found (A and a; B and p). Taking into account the presence of agglutinogens and agglutinins, human blood is divided into four groups (Table 3).

Classification of human blood groups As shown in Table 3, in the first (I) blood group, its plasma contains both agglutinins (a and -

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