External and internal stimuli. The All or Nothing Law

Irritants- these are factors of the external or internal environment that have a reserve of energy and, under the action of which, their effect on the tissue is noted. biological response.

Classification of stimuli depends on what is taken as a basis:

1. By your own nature irritants are:

chemical

physical

mechanical

thermal

biological

2.By biological conformity, that is, how much the stimulus corresponds to this tissue:

adequate- irritants that correspond given fabric. For example, for the retina of the eye, light - all other stimuli do not correspond to the retina, for muscle tissue- nerve impulse, etc.;

inadequate- irritants that do not correspond given fabric. For the retina of the eye, all stimuli except light will be inadequate, and for muscle tissue all stimuli except nerve impulses.

3.According to strength There are five main stimuli:

subthreshold stimuli- is the strength of the stimulus at which no response occurs;

threshold stimulus- this is the minimum force that causes a response with an infinite duration of action. This force is also called rheobase- it is unique for each tissue;

suprathreshold, or submaximal;

maximum stimulus is the minimum force at which the maximum response occurs tissue reaction;

supramaximal stimuli- with these stimuli, the tissue reaction is either maximum, or decreases, or temporarily disappears.

For each tissue there is one threshold stimulus, one maximum and many subthreshold, suprathreshold and supermaximal.

Irritation are any effects on the tissue. In response to stimuli, biological reactions fabrics.

Irritability is a universal property of living matter and reflects the ability of any living tissue to change its non-specific activity under the influence of irritation.

Ticket 3. The concepts of excitability and arousal.

There are three functional states of tissue: rest, excitation and inhibition.

State rest- this is a passive process in which there are no externally expressed manifestations of specific activity (reduction, secretion, etc.).

State arousal and braking- these are active processes in which, in one case, the specific activity of the tissue (excitation) is enhanced, and in the other, the manifestation of specific activity either completely disappears or decreases, although the stimulus continues to act on the tissue.

Two types of biological reactions:

specific

non-specific

Specific reactions are characteristic of some strictly defined tissue (a specific reaction of muscle tissue is contraction, for glandular tissue it is the secretion or hormone secretion, for nervous tissue it is the generation and transmission of a nerve impulse). Thus, specialized tissues have specific activities.

Nonspecific reactions characteristic of any living tissue. For example, a change in the intensity of metabolism, a change in the resting membrane potential, a change in the ion gradient, etc.

Excitability is a property of specialized tissues and reflects ability tissues respond to irritation by changing their specific reactions. The excitability of a tissue is determined by its threshold strength: the lower the threshold strength, the greater the excitability of the tissue.

Excitation- it is specific tissue reaction

Threshold of excitability (excitation)- the smallest strength of the stimulus, causing the least excitation. With threshold excitation, the activity of an organ or tissue is extremely small.

The strength of the stimulus less than the threshold is called subthreshold, more than the threshold - suprathreshold. The greater the excitability of the tissue, the lower the threshold, and vice versa. With a stronger stimulus, there is more excitation, and consequently, the magnitude of the activity of the excited organ increases. For example, the stronger the irritation, the greater the height of contraction of the skeletal muscle. The stronger the stimulus, the shorter its action, causing minimal excitation, and vice versa. useful time- the shortest time of action of the stimulus of threshold strength, or reobase, causing minimal excitation. However, this time is difficult to determine, therefore, the shortest time of action of the double rheobase stimulus, which is called chronaxia, is determined.

Ticket 4. The history of the discovery of bioelectric phenomena. The nature of arousal.

The origin of the doctrine of "animal electricity", that is, about bioelectric phenomena, arising in living tissues, refers to the second half of the XVIII century. Shortly after the discovery of the Leyden jar, it was shown that some fish (electric ray, electric eel) immobilize their prey by striking it with a strong electrical discharge. At the same time, J. Priestley suggested that the propagation of a nerve impulse is a flow along the nerve of an "electric fluid", and Bertolon tried to build a theory of medicine, explaining the occurrence of diseases by excess and deficiency of this fluid in the body.

An attempt to consistently develop the doctrine of "animal electricity" was made by L. Galvani in his famous "Treatise on the forces of electricity in motion" (1791). Being engaged in the study of the physiological influence of the discharges of an electric machine, as well as atmospheric electricity during lightning discharges, Galvani in his experiments used a preparation of frog hind legs connected to the spine. Hanging this preparation on a copper hook from the iron railing of the balcony, he noticed that when the frog's legs were swayed by the wind, their muscles contracted at each touch on the railing. Based on this, Galvani came to the conclusion that the twitching of the legs was caused by "animal electricity" originating in the spinal cord of the frog and transmitted through metal conductors (the hook and balcony railing) to the muscles of the leg.

Galvani's experiments were repeated by A. Volta (1792) and found that the phenomena described by Galvani cannot be considered due to "animal electricity"; in Galvani's experiments, the current source was not the spinal cord of a frog, but a circuit formed from dissimilar metals - copper and iron. In response to Volta's objections, Galvani produced a new experiment, this time without the participation of metals. He showed that if the skin is removed from the hind limbs of the frog, then the sciatic nerve is cut at the point where its roots exit the spinal cord and the nerve is cut along the thigh to the lower leg, then when the nerve is thrown over the exposed muscles of the lower leg, they contract. O. Dubois-Reymond called this experience "the true basic experience of neuromuscular physiology."

With the invention in the 20s of the XIX century galvanometer(multiplier) and other electrical measuring instruments, physiologists were able to accurately measure the electrical currents that occur in living tissues using special physical instruments.

With the help of the multiplier K. Matteuchi (1838) first showed that the outer surface of the muscle is electropositively charged with respect to its inner contents, and this potential difference, characteristic of the state of rest, drops sharply when excited. Matteuchi also made an experiment known as secondary contraction experience: when a second neuromuscular preparation is applied to the contracting muscle of the nerve, its muscle also contracts. Matteuchi's experience is explained by the fact that the action potentials arising in the muscle during excitation are strong enough to cause excitation of the nerve attached to the first muscle, and this entails a contraction of the second muscle.

The most complete teaching bioelectric phenomena in living tissues was developed in the 40-50s of the last century by E. Dubois-Reymond. His special merit is the technical impeccability of the experiments. With the help of a galvanometer, an induction apparatus and non-polarizing electrodes improved by him and adapted to the needs of physiology, Dubois-Reymond gave irrefutable evidence of the presence of electrical potentials in living tissues both at rest and during excitation. During the second half of the 19th and in the 20th century, the technique of recording biopotentials was continuously improved. So, in the 80s of the last century, N. E. Vvedensky used a telephone in electrophysiological studies, Lippmann used a capillary electrometer, and at the beginning of our century, V. Einthoven used a string galvanometer.

Thanks to the development of electronics, physiology has at its disposal very advanced electrical measuring instruments with low inertia (stub oscilloscopes) and even almost inertialess (cathode ray tubes). The necessary degree of amplification of biocurrents is provided electronic and AC and DC amplifiers. Microphysiological methods of research have been developed, allowing to divert potentials from single nerve and muscle cells and nerve fibers. In this regard, the use of studies of giant nerve fibers (axons) of the cephalopod squid. Their diameter reaches 1 mm, which makes it possible to introduce thin electrodes into the fiber, perfuse it with solutions of various compositions, and use labeled ions to study the ion permeability of the excitable membrane. Modern ideas about the mechanism of the emergence of biopotentials are largely based on data obtained in experiments on such axons.

Ticket 5. The plasma membrane and its role in the metabolism between the cell and the environment.

Cell (plasma) membrane is a semi-permeable barrier separating the cytoplasm of cells from the environment.

1. The membrane consists of a double layer of lipid molecules. Hydrophilic, polar parts of molecules (heads) are located outside the membrane, hydrophobic, non-polar parts (tail) - inside.

2. Membrane proteins are mosaically embedded in the lipid bilayer. Some of them pass through the membrane through (they are called integral), others are located on the outer or inner surface of the membrane (they are called peripheral).

3. The lipid base of the membrane has the properties of a liquid (such as liquid oil) and can change its density. Membrane viscosity depends on lipid composition and temperature. In this regard, membrane proteins and lipids themselves can move freely along the membrane and inside it.

4. The membranes of most intracellular membrane organelles are fundamentally similar to the plasma membrane.

5. Despite the common structure of the membranes of all cells, the composition of proteins and lipids in each type of cell and inside the cell is different. The composition of the outer and inner lipid layers is also different.

Functions:

1) Barrier- provides a regulated, selective, passive and active metabolism with the environment. Selective permeability means that the permeability of a membrane to various atoms or molecules depends on their size, electrical charge, and chemical properties. Selective permeability ensures the separation of the cell and cellular compartments from the environment and supply them with the necessary substances.

2) Transport- transport of substances into and out of the cell occurs through the membrane. Transport across membranes provides:

nutrient delivery

removal of end products of metabolism

secretion of various substances

creating ionic gradients

maintaining the optimal pH and concentration of ions in the cell, which are necessary for the work of cellular enzymes

3) Matrix- provides a certain relative position and orientation of membrane proteins, their optimal interaction.

4)Mechanical- ensures the autonomy of the cell, its intracellular structures, as well as connection with other cells (in tissues). Cell walls play an important role in providing mechanical function, and in animals - intercellular substance.

5) Energy- during photosynthesis in chloroplasts and cellular respiration in mitochondria, energy transfer systems operate in their membranes, in which proteins also participate.

6)Receptor- some proteins in the membrane are receptors (molecules by which the cell perceives certain signals).

7)Enzymatic Membrane proteins are often enzymes.

8)Implementation of generation and conduction biopotentials. With the help of the membrane, a constant concentration of ions is maintained in the cell: the concentration of the K + ion inside the cell is much higher than outside, and the concentration of Na + is much lower, which is very important, since this maintains the potential difference across the membrane and generates a nerve impulse.

9) Cell labeling- there are antigens on the membrane that act as markers - "labels" that allow you to identify the cell. These are glycoproteins (that is, proteins with branched oligosaccharide side chains attached to them) that play the role of "antennas". With the help of markers, cells can recognize other cells and act in concert with them, for example, when forming organs and tissues. This also allows immune system recognize foreign antigens.

Ticket 6. Membrane excitation theory. Passive transport of substances across a membrane. Potassium-sodium pump.

Membrane excitation theory- in physiology - proceeds from the idea that when a living cell (nerve, muscle) is irritated, the permeability of its surface membrane changes, which leads to the emergence of transmembrane ion currents.

concentration gradient is a vector physical quantity that characterizes the magnitude and direction of the greatest change in the concentration of any substance in the environment. For example, if we consider two regions with different concentrations of a substance separated by a semipermeable membrane, then the concentration gradient will be directed from the region of lower concentration of the substance to the region with its higher concentration.

Passive transport- transfer of substances along a concentration gradient from an area of high concentration to an area of low concentration without energy expenditure (for example, diffusion, osmosis). Diffusion is the passive movement of a substance from an area of higher concentration to an area of lower concentration. Osmosis - passive movement of certain substances through a semipermeable membrane (usually small molecules pass, large ones do not). There are three types of penetration of substances into a cell through membranes: simple diffusion, facilitated diffusion, active transport.

Among examples of active transport against a concentration gradient, the sodium-potassium pump has been best studied. During its operation, three positive Na + ions are transferred from the cell for every two positive K ions into the cell. This work is accompanied by the accumulation of a difference in electrical potentials on the membrane. At the same time, ATP is broken down, giving energy. works on the principle of a peristaltic pump.

Ticket 7. The mechanism of occurrence of the membrane potential and its changes under the influence of various factors.

Normally, when a nerve cell is at physiological rest and ready to work, it has already undergone a redistribution of electrical charges between the inner and outer sides of the membrane. Due to this, an electric field arose, and an electric potential appeared on the membrane - resting membrane potential.

resting potential- this is the difference in electrical potentials available on the inner and outer sides of the membrane when the cell is in a state of physiological rest. (cell outside +, and inside -.). The secret of the emergence of negativity in the cell: first, it exchanges "its" sodium for "foreign" potassium (yes, some positive ions for others, the same positive ones); then these "named" positive potassium ions leak out of it, along with which positive charges flow out of the cell. What is important here is that exchange of sodium for potassium - unequal. For every cell given three sodium ions she gets everything two potassium ions. This results in the loss of one positive charge with each ion exchange event. So already at this stage, due to unequal exchange, the cell loses more “pluses” than it receives in return. creating a difference inside and out.

Next comes The concentration potential is part of the resting potential, created by a deficit of positive charges inside the cell, formed due to the leakage of positive potassium ions from it.

Ticket 8. Action potential. The mechanism of its occurrence.

action potential- a wave of excitation moving along the membrane of a living cell in the process of transmitting a nerve signal. In essence, it represents electrical discharge- a rapid short-term change in potential on a small section of the membrane of an excitable cell (neuron, muscle fiber or glandular cell), as a result of which the outer surface of this section becomes negatively charged with respect to neighboring sections of the membrane, while its inner surface becomes positively charged with respect to neighboring sections of the membrane. An action potential is the physical basis of a nerve or muscle impulse.

Ticket 9. Waves of excitation, its components.

If an irritant of sufficient strength and duration is applied to a living tissue, then excitation occurs in it, which manifests itself in changes in the electrical state of the membrane. The set of successive changes in the electrical state of the membrane is called an excitation wave. For the first time, a wave of excitation was registered by K. Cole, H. Curtis (1938-1939), who introduced one electrode into the process of the squid nerve cell, and the second was placed in sea water, in which the process was immersed. Having connected the electrodes to the appropriate equipment, they first registered the MF, and upon stimulation, an excitation wave. The components of the excitation wave are:

threshold potential;

Action potential - PD;

trace potentials.

The cause of the excitation wave is a change in the ion permeability of the membrane. Under the action of an irritant, the permeability of the cell membrane for Na + increases, sodium ions diffuse into the cell. In accordance with the decrease in the electropositive charge of the outer side of the membrane, the electronegative charge of the inner side of the membrane decreases. There is a depolarization of the membrane - a decrease in MP. At the first moment, depolarization proceeds slowly, the MP decreases only by 15-25 Go. The initial depolarization is called the local (local) response. Depolarization continues and reaches a critical (threshold level - such a value of the MP at which depolarization sharply increases - the critical potential. The difference between the MP and the critical potential is called the threshold potential. When the MP decreases by an amount equal to the threshold potential, an action potential arises (rapid changes in the MP, electrical impulse). It consists of a phase of depolarization and repolarization, which correspond to the ascending and descending curve of the excitation wave. The MP decreases in absolute value to zero and changes its sign to the opposite. The peak of the action potential falls on the period when the membrane is recharged - potential reversion. The outer side of the membrane is charged negatively, the inner - positively.After that, the phase of repolarization begins - the restoration of the initial level of polarization.The permeability of the membrane for Na + ions decreases, and for K + increases.K + ions diffuse from the cell to the outer surface b membrane, charging it positively. During the period when the permeability of the membrane for K + during repolarization decreases, and repolarization is slower than in the descending part of the Yu peak, then hypopolarization of the membrane is observed (negative trace potential). The original value of MP is restored. After that, in many cells, an increased permeability of the membrane for K + is observed for some time, in connection with this, the MP begins to grow - the membrane hyperpolarization occurs (a positive trace potential arises) Generating Yu, the cell each time receives a certain amount of Na + and loses K +. However, the concentration of ions in the cell and the intercellular substance does not equalize, which is due to the action of the sodium-potassium pump, which removes Na+ from the cell and allows K+ into the cell.

Ticket 10. Absolute and relative refractory phases.

During the excitation process, the excitability of tissues changes. There are periods of excitability:

1. Initial increase in excitability. Observed during local (local) responses.

2. Refractory - a temporary decrease in tissue excitability. There are phases:

Absolute refractoriness - complete non-excitability during the period of C growth, excitement in this phase cannot be caused, even if the stimulus acts above the threshold force.

Relative refractoriness - excitability is reduced during the period of AP decrease, in order to cause excitation, it is necessary to act with an irritant of suprathreshold strength.

2. Supernormal - increased excitability, it is possible to cause excitation with a very weak stimulus of subthreshold strength. Corresponds to trace negative potential.

3. Subnormal - reduced excitability in comparison with its initial level. Coincides with positive trace potential. After that, the initial level of excitability is restored.

Ticket 11. The concept of lability, or functional mobility

Lability (functional mobility) is a property of nervous processes (nervous system), which manifests itself in the ability to conduct a certain number of nerve impulses per unit of time. Lability also characterizes the rate of occurrence and termination of the nervous process.

The rate of elementary cycles of excitation in the nervous and muscle tissues.

The concept was introduced by the Russian physiologist N. E. Vvedensky, who considered the measure of L. to be the highest frequency of tissue stimulation reproduced by it without rhythm transformation. L. reflects the time during which the tissue restores performance after the next cycle of excitation.

The greatest L. differ axon s , capable of reproducing up to 500-1000 pulses per 1 sec; less labile synapses(for example, a motor nerve ending can transmit no more than 100-150 excitations to a skeletal muscle in 1 sec).

L. is a variable value. So, in the heart, under the influence of frequent irritations, L increases. This phenomenon underlies the so-called. learning the rhythm. The doctrine of L. is important for understanding the mechanisms of nervous activity, the work of nerve centers and analyzers, both in the norm and in various painful deviations.

Ticket 12. Summation and its types.

Summation- the interaction of synoptic processes (excitatory and inhibitory) on the membrane of a neuron or muscle cell, characterized by an increase in the effects of irritation to a reflex reaction. The phenomenon of S. as a characteristic property of the nerve centers was first described by I.. M. Sechenov in 1868.

At the system level, summation is distinguished:

Spatial

Temporary

Spatial S. detected in the case of simultaneous action of several. spatially separated afferent stimuli, each of which is ineffective for different receptors of the same receptive zone.

temporary S. consists in the interaction of nerve influences coming from a certain. interval to the same excitable structures along the same nerve channels. At the cellular level, such a distinction between S.'s species is not justified, therefore it is called. space-time. S. - one of the mechanisms for the implementation of coordination. body reactions.

Summation of excitation in the central formations of the reflex arc. Two stimuli applied separately to different areas of the skin (lowering lines 1 and 2) do not cause a reflex response. When two stimuli are applied simultaneously, a strong scratching reflex occurs (upper entry).

Ticket 13. Interneuronal connections, the mechanism of excitation transfer in synapses.

Contacts between neurons, carried out through synapses (axonosomatic, axonodendric, axon-axonal

Two types of interneuronal connections should be distinguished:

1) local - synaptic

2) "diffuse, non-synaptic”, carried out through the influence on the surrounding cells of neuroactive substances circulating in the intercellular spaces.

They have a modulating effect on electrogenesis and many vital processes in nerve cells.

Existing interneuronal connections Sherrington called synapses. Synapse- This is a structural formation where the transition of one nerve fiber to another, or the transition of a nerve to a neuron and a muscle, occurs. The synaptic section of the axon is characterized by an accumulation of small round bodies - synaptic vesicles (vesicles) with a diameter of 10 to 20 nm. These vesicles contain a specific substance that is released when the axon is excited and is called mediator. The end of an axon with vesicles is called presynaptic membrane. The section of a nerve, neuron, or muscle where it is directly transmitted excitation called postsynaptic membrane. Between these two structures there is a small gap (no more than 50 nm), which is called synaptic cleft. Thus, any synapse consists of three parts: presynaptic membrane, synaptic cleft and postsynaptic membrane).

From the foregoing, it follows that in synapses, the transmission of excitation is carried out by a chemical method and this occurs due to three processes:

1) the release of the mediator from the bubbles;

2) diffusion of the mediator into the synaptic cleft

3) the connection of this mediator with specific reactive structures of the postsynaptic membrane, which leads to the formation of a new impulse.

Irritants are factors of the external or internal environment that cause excitement, hypersensitivity and other mental or physical reactions. We respond to many different stimuli. They influence our behavior, sensations and well-being. Some environmental factors can have a direct impact on metabolism, the activity of the body's defense system and general well-being. Many external stimuli are simply necessary to maintain the vital functions of the body. For example, under the influence of sunlight, the skin acquires a brown tint - this is a protective reaction of the skin that protects the body from the harmful effects of ultraviolet rays. High temperature is also an irritant. It causes sweating, which is the main means of thermoregulation of the body.

The occurrence of many undesirable reactions is due to atmospheric pollution and other environmental factors. Every day, chemicals are created that have an irritating effect on the body.

The influence of external stimuli on a person

According to the observations of doctors, over the past few decades, the number of people suffering from allergic diseases has increased. Of course, not in every case it is possible to accurately determine the causes of an allergic disease, but it is assumed that most often allergies occur under the influence of harmful environmental factors. According to doctors, very rarely a person is allergic to only one substance. It is very dangerous when the human immune system is hypersensitive to many substances. In this case, it is subjected to a huge load, because. must constantly adapt to new, unknown stimuli. The immune system, as it were, is in a state of constant readiness and sometimes reacts too violently to absolutely harmless substances, which manifests itself in the form of an allergy.

Reaction to external stimuli

It is impossible to avoid exposure to harmful environmental factors. Over time, the human body gets used to a particular stimulus and ceases to be sensitive to it. For example, housewives who spend a lot of time in the kitchen tolerate heat more easily than other people. The reaction to stimuli can change - intensify or weaken. For example, patients with chronic pain get used to them over time.

Hyposensitization

This is a method of treatment, the use of which allows you to reduce the body's sensitivity to the allergen, and often cope with allergies. The patient is given small doses of the allergen in order to become addictive. Doses are gradually increased, which leads to a decrease in the sensitivity of the body. The procedures are repeated until the allergy subsides. The allergen should not be administered to pregnant women, as well as to women during menstruation, a few days before and after them. If the allergen is not established, then nonspecific hyposensitization is carried out, which consists in the use of physiotherapeutic agents, climatotherapy, and acupuncture. One of the most effective methods of mitigating the effects of excess stimuli is autogenic training. This method allows you to cure mild forms of allergic diseases. By the way, positive results are achieved with the use of many other methods of relaxation.

Hyposensitization is not carried out in all cases (it requires a lot of patience from the patient, since the treatment lasts a very long time). This method can only be used by an experienced doctor (allergist).

Beneficial irritants

There are many irritants that have a positive effect on the body. For example, climatotherapy, massage, heat or cold treatment, and many other similar methods contribute to recovery and maintaining health. Many medicines and vaccines have an irritating effect on the body and the immune system (they help the body cope with diseases). In homeopathy, substances that cause disease are used as medicines. They are repeatedly diluted and given to the patient. Homeopathic remedies promote spontaneous recovery.

Information and vital activity of the organism

The vital activity of the body or the performance of a certain work (training) is a constant work of the morphological structures of the body. The number of structures included in the work is regulated by changing the influences (conditions) of the external environment with its biotic and abiotic components. Particular attention should be paid to constantly acting factors: the composition of atmospheric air, water, geomagnetic field, radiation from instruments and various broadcasting radio and television stations, penetrating radiation, ultraviolet studies, etc. Part these factors play a major role in changing microstructures. Constantly operating external factors are extremely important, the disappearance of one of them can affect the life of the organism, strengthening or inhibiting it.

Biotic factors - interaction with wildlife with pathogenic and saprophytic microorganisms - should be taken seriously as anthropogenic and social factors.

Living matter is inherent in the reflection of the external environment, which begins with the perception of information. Information is always material, as it leads to various (chemical, biochemical, electrical) shifts in the body. A change in the strength of the flow of information, its frequency, decrease or increase - always leads to responses from individual body systems. A disappearing or appearing stream of information (it can be a word) is called an irritant.

The perception of information is produced by special structures called receptors. The receptor, otherwise the receiver, as a rule, is a specialized nerve ending that can transform an external stimulus into a bioelectric signal. Receptors are the beginning of afferent (sensory) nerve fibers. They can perceive irritation from the external and internal environment. Perceiving receptors from the external environment are called exteroreceptors. They can be contact - perceiving irritation in direct contact with the object (environment), or distant - perceiving signals (information) at a distance.

Receptors that carry information from muscles (muscle-articular spindles), tendons, fascia, articular capsules, periosteum, are called proprioreceptors. They signal to the central nervous system about the state of tension and relaxation of the listed formations and thereby create conditions for characterizing individual joints or the body as a whole.

There are also interoreceptors - informing the central nervous system about the state of internal organs, blood vessels, etc. Each receptor is “tuned” to perceive a specific stimulus. The structure of the receptor is based on glycoproteins or glycolipids. There are extremely many receptor endings, so there are about 250,000 molecular receptors on one liver cell. Not all receptors are associated with the CNS. Information is transmitted from cell to cell through intercellular contacts, by passing through the membranes of molecular structures. Such a mechanism for transmitting information is called pre-nervous, or chemical transmission of irritation.

When the receptor meets the stimulus, the mechanism of the molecular response is triggered - the molecular rearrangement of the membranes, the activation of enzymes located in the membrane occurs. The process of irritation of one cell receptor leads to the activation of the entire cell as a whole in the form of an increase in its functional activity. Through intercellular contacts, the stimulus is transmitted to neighboring structures, reaching the nerve receptor.

Nerve receptors are the initial structures of the dendrites of sensitive cells. They are found in all tissues and organs. Usually, receptors of the same name are grouped together, forming sensory fields (or systems). The transmission of irritation along the dendrites (and axons) occurs in the form of an electrical potential, which occurs as a result of a change in the permeability of the cell membrane for potassium and sodium and the movement of negative and positive charges on the inner and outer sides of the membrane.

The transmission of irritation from a nerve cell to a nerve cell occurs through special formations - synapses with the help of molecular structures - mediators. The "transmitting" structure of the synapse is always located on a branched branch of the nerve cell. The "receiving" part can be located on any part of the membrane of the nerve cell - the performer. The energy of nerve impulse transmission is always produced by ATP.

It should be noted that the perception of information always occurs due to counteraction, leading to an increase in the activity of the irritated structure. The nature of the response may be different and depends on the nature, power of the stimulus, the duration of its action. In the transfer of irritation, Schultz's rule applies, according to which weak stimuli do not have an effect, medium ones stimulate, strong ones depress, super-strong ones disrupt vital activity.

The concept of reactivity

Reactivity (reaction rate) is usually called the property of an organism to respond with a change in activity to external influences. Reactivity is closely related to the main factors of life: heredity, the activity of the nervous system, metabolism, nutrition. Reactivity is associated with the vital activity of the organism, with its protective and adaptive nature.

Against the background of general biological activity, individual activity is formed, which is characterized by broad responses in response to the same stimuli. The factors that determine the strength of individual reactivity are determined by a number of biological features: heredity, constitutional features, gender, age of the subject, the state of the nervous and endocrine systems, health status, pre-setting and experience.

In sports practice, individual reactivity, as nowhere else, is of great importance. It is known that at the peak of the form, reactivity can decrease sharply - sensitivity to factors that were previously neutral appears. So, before the competition, athletes often catch colds, get sick with tonsillitis, and react to changes in barometric pressure.

Effects on the body of physiological and emergency stimuli

Physiological (normal or adequate) are called such loads and stimuli, in response to which the body (cell, organ, organ system), the biological system increases its specific activity, that is, it performs work in which the energy consumption of structures and their synthesis does not exceed the level of physiological fluctuations characteristic of specific biological systems. An adequate stimulus, acting on the receptor apparatus, causes its characteristic activity with minimal energy expenditure and loading of the working structures. An adequate stimulus does not always correspond to the “normal” for the organism, sometimes with a shift in reactivity it becomes extreme, sometimes minimal.

All other stimuli I. P. Pavlov proposed to call "extraordinary", or "extreme", or "inadequate".

An example of a strong response to a minimal stimulus would be a word. The word of the coach (remarks, instructions) evokes a bright response from the student, the same word of a training mate can be neutral, remain unanswered by the structures of the body.

In response to an extreme stimulus, biological systems (organism, apparatus, etc.) respond with extraordinary activity - a sharp increase in function, leading to the destruction of structures (up to microtrauma). The balance between the destruction and reconstruction of existing structures is disturbed - homeostasis is disturbed. If the situation repeats, overtraining necessarily occurs, a breakdown in adaptation. After exposure to an emergency stimulus, an ordinary, adequate stimulus acquires all the features of an emergency stimulus. Extreme, or inadequate, irritants can be:
- physiological stimuli acting on the biological system, which is currently in an excited state;
- physiological stimuli, but significantly long-acting on the system, or at a high pace;
- irritants with which the body meets for the first time or has an increased sensitivity to them;
- the absence or a sharp decrease in the value of a permanent acting factor (gravity, force or magnetic field, unusual food, water, etc.).

Irritants in physical culture and sports

A child who has begun to go in for sports is faced with new unusual stimuli at each lesson. At first, the responses are violent, inadequate, but over time they smooth out.

Physical activity is a very powerful factor in the external environment, but it is an easily dosed factor - this is their excellent property. In skillful hands, they mold an organism resistant to external stimuli, as if from plasticine.

Physical loads in sports are usually distinguished by the power of impact (maximum, submaximal, large, moderate, variable), by the nature of the impact (cyclic, acyclic, single, repeated), by the time of exposure (short-term, long-term).

The initial physical education, and then sports, falls on the first childhood or the pre-preschool period. This is a period of increased sensitivity, and the dosage of loads should not only be strictly defined, but must necessarily correspond to the somatic characteristics of the child and his developmental variant. The coach must remember that tomorrow's child is a child with new reactivity, with altered homeostasis. In the period up to 6 years, time passes at an accelerated pace, creating new structures and new functions.

For athletes 10-16 years old, the approach should be different. The time spent on the creation and renewal of intracellular structures is stretched, but changes from six months to six months due to the entry into the active period of the endocrine glands (prepubertal and pubertal period). The reactivity of the body becomes unstable, gomiorez? mobile and controlled by external factors. The experience of the coach and the observation of responses are tools for reasonable dosing of loads. During this period, strict pedagogical and medical control is necessary to prevent the adverse effects of inadequate loads. It is also necessary to pay attention to the fact that the former normal (adequate) loads become maximum, so recovery factors, etc. are needed.
Anthropogenic factors are added to physical loads in an athlete in the pre-competitive and competitive periods - a change in his own emotional state, the impact of the public, distracting factors, spotlights, etc.

Athletes during the training period constantly have additional factors that an ordinary teenager almost does not feel at physical education lessons - these are angular accelerations, changes in the forces of gravity, displacement of internal organs, short-term weightlessness. Hygiene factors serve as smoothing points: hygienic conditions for training, hardening, nutritional habits, etc.

Changing structures in response to training influences

All stimuli are inherently similar in their effect on the vital activity of the organism, if not in macro-, then in microstructures. The unifying factor is metabolic processes, metabolism, energy and information. The life and work of any organism, organ, cell, organoid is possible only due to the consumption of energy and structures. In the process of work (training), cell structures wear out and are restored in quantities proportional to work. With prolonged exposure, excessive recovery occurs, that is, a destroyed organoid is built plus a new one. In general, the formation of energy in the cells of the human body occurs due to complex transformations of animal and vegetable proteins, fats, carbohydrates and oxygen entering the body. In each cell separately, by anaerobic and aerobic breakdown of glucose and fatty acids, a universal energy carrier, ATP, is formed, which provides all the functions of the cell. For the formation of this universal energy carrier, in addition to glucose and fatty acids, various classes of enzymes (protein molecules) are needed that catalyze the breakdown and synthesis, as well as protein structures - matrices on which oxidation and synthesis occur.

To ensure normal life, it is necessary to receive from the external environment: animal and vegetable proteins - 125 g, fats - 75 g, carbohydrates - 450 g, oxygen - 460 l, water - 2-2.5 l and many (up to 40 items) other components . During the day, 30-70 kg of ATP is synthesized and broken down.

Consequently, the performance of any function of the body, the maintenance of life is always associated with the expenditure of energy, the disintegration of some structures and the simultaneous synthesis of energy substances and the restoration of damaged structures. In this case, the external environment plays the role of the receipt of "semi-finished products" and information. An organism exists as long as two mutually opposite processes - decay and synthesis - steadfastly balance each other and maintain the unity of structure and function. Violation of these processes leads to the death of either a cell, or an organ, or an organism.

The vital activity of any structure, cell, tissue, organ, organism is necessarily characterized by two types of work - internal and external.

Inner work goes on without interruption, not stopping even for a minute. This work includes the processing of incoming nutrients, the formation of energy, the synthesis of protein-lipid components, the replacement of worn-out structures, and the generation of heat. Internal work is aimed at maintaining homeostasis.

External work is done periodically. Its basis is inner work. External work is not only the movement of the body in space or the movement of individual links of the body relative to each other. This work also includes secretion, neutralization and removal of decay products, heat generation due to muscle contraction, etc.

Sports movements are also a product of inner work. In preschool children, most of the energy is spent on maintaining body position and posture, on performing simple movements due to an unstable coordination system. However, a 2-year-old child spends energy on simple movements, according to N. A. Bernshtein, much less than an adult subject, since the child’s movements are to a greater extent performed using inertia. Biomechanical and energy processes follow the same pattern as in an adult.

Long-term observations of a person during the day showed that energy consumption at different hours of the day differ significantly, as does the reactivity of the body. In the morning, power supply systems are less active than after 15:00. Therefore, competitions in a number of sports are held in the evening hours.

Biorhythms and their characteristics

It is impossible to speak or write about age-related morphology, about sports morphology, tearing it away from the temporal characteristics of the processes occurring in the body. It is impossible to separate the spatial and temporal characteristics of an organism, just as it is impossible to imagine the universe without movement. Movements are present in all life processes, as they proceed rhythmically. The change in a child during childhood is striking due to the ongoing macrochanges, but it is also present in a mature, aging organism, just on a different level. Adaptation of the whole organism to new environmental conditions, including high physical loads, is provided not by individual organs, but by specialized functional systems coordinated in space and time and subordinated to each other. Rational preparation of the body (training) is impossible without knowledge of the nature of biorhythms. Sports training is based on ideas about the mechanisms of long-term adaptation, about the interaction of load and recovery of the body as factors that cause adaptation processes that manifest themselves in structural and functional transformations in the athlete's body.

Recall anatomy - the human body has a large number of organs and structures of the same name, especially at the tissue and cellular level of organization. So, in the body there are two kidneys, two adrenal glands, etc., even the nervous system has two hemispheres. Consider a kidney. Each kidney consists of about 1 million nephrons, each nephron has many glomeruli, and so on. Such a multitude of structures with the same names at first suggested the idea of their alternating work. This was confirmed, the organs of the same name work alternately - one hemisphere of the brain is awake, the other “rests”. T. N. Kryzhanovsky proved that in the body there is a principle of non-simultaneity of the work of similar structures. The structures of the same name include paired organs, synergistic organs, structural and functional units - for example, muscle fibers, liver lobules, lung acini, gland lobules, individual cells of the same name, organelles (nucleoli, mitochondria, lysosomes, ribosomes). The adjacent structures usually work in alternation or are at different levels of functioning. The principle of asynchrony of working cycles of similar structures ensures the rhythmic, cyclic work of intracellular structures, creates optimal conditions for work and "rest" for any structure. With an increase in work, the number of working structures also increases, without bringing the previously working structures to destruction.

You should also pay attention to the multifunctionality of cells (the prefix "poly-" indicates a multipurpose purpose). From the course of anatomy, we know that the same organ can perform a number of dissimilar actions, and in extreme situations they can take over the function of a damaged organ. Such polyfunctional cells include smooth muscle cells, mast cells, macrophages, fibroblasts, and hepatocytes. The material basis of polyfunctionality is the qualitative features of the structure of cell organs. It has been established that the same cell organelles can synthesize different secrets. These features of the work of cells create conditions for the rapid intensification of work and the restoration of any function. The dispersal of cells capable of performing the same functions creates greater reliability of the entire biological system.

The periodicity of irritations, combined with asynchrony, and the polyfunctionality of cells determine the periodicity of the change in functional activity and functional rest of structures - the rhythm of the work of the entire organ or organism as a whole. This rhythm of work is based on the biorhythms of living structures, which are under the most complex control of hereditary, environmental, endocrine factors, as well as under the influence of cosmic laws. An example is the deterioration in the condition of weather-sensitive people to changes in the phases of the moon or solar flares.

Biorhythms are integral properties of any biological system, their study will undoubtedly allow to rebuild the individual training of athletes, and in children to bring the given loads closer to the individual rhythm of life.

The rhythm of life changes gradually with age. In children, the rhythm of sleep and wakefulness undergoes significant changes over the course of a year, finally being established in the form of an individual by the age of 7. However, in all animals and humans, by the period of the onset of puberty, the daily rhythm of life is clearly established, that is, every 24 hours, changes in activity and inhibition of the systems activity occur in a certain order. This rhythm is called the circadian rhythm, however, within the daily rhythm there are wide variations in the duration of a particular process. They are regulated, from the point of view of some researchers, by the change and permeability of cell membranes for sodium and potassium ions. This theory found its supporters, but later another substantiated theory appeared, stating that the individual rhythm depends on the RNA-DNA ratio. These amino acids are considered the "mistresses" of biorhythms. At present, the "theory of periodic processes" prevails, based on the rhythm of the entry of substances into the cell and their utilization. One way or another, but the problem is undoubtedly related to the biochemistry and morphology of cellular structures. Rhythms are a reality waiting for their researchers and thinkers who will build a theory of their origin and existence. Each person has his own heart rate, his own rhythm of utilization of substances coming from food, but in all cases it is associated with maintaining optimal homeostasis. You can change your own rhythm by directed influences. The highest activity is observed between 4 and 5 o'clock in the morning, but we wake up safely during this period.

Directed rhythmic exercises can strengthen your own rhythm, increase volitional qualities and vitality, and possibly loosen and come to a state that is called "vegetative neurosis".

The works of recent years on biorhythmology, carried out in preschool institutions, have shown that in those kindergartens where rhythmic gymnastics classes are systematically held, where general developmental exercises are combined with elements of rhythmic gymnastics, children get sick less and tolerate diseases more easily.

IRRITANTS

IRRITANTS environmental factors that have an effect on the receptors of animals, expressed in a change in the activity of the latter. In accordance with the physical nature of the impact, stimuli are divided into light, sound, mechanical, thermal, etc.

Ecological encyclopedic dictionary. - Chisinau: Main edition of the Moldavian Soviet Encyclopedia. I.I. Grandpa. 1989

See what "IRRITATIVES" are in other dictionaries:

- (biological) various changes in the state of the external or internal environment of the body, capable of changing its initial state, i.e., causing ... ... Great Soviet Encyclopedia

Different types of electrical energy (galvanic current, faradic current, static electricity) have the ability to irritate the tissues of the animal body, as a result of which they constitute the so-called in relation to these tissues. E. irritants. ... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

App., number of synonyms: 2 unflappable (31) calm (90) ASIS Synonym Dictionary. V.N. Trishin. 2013 ... Synonym dictionary

Irrelevant Stimuli- (fr. irrelevant - irrelevant). Words that, being included in the associative experiment as stimuli, do not cause affective reactions. In contrast, non-indifferent stimuli are stimuli for this kind of ... ... Explanatory Dictionary of Psychiatric Terms

Distracting stimuli- any stimuli and environmental phenomena that cause an orienting reaction or interest of the dog. Distracting the dog's attention, O. p. interfere with the training process. In this regard, the first stage of developing a skill is the formation of a conditioned reflex reaction - ... ... Dictionary of trainer

Irrelevant Irritants- Irrelevant irritants, such words, which do not cause affective reactions during the associative experiment. When a subject, in response to a spoken or read word, is asked to answer with the first word that came to his mind, then some ... ... Big Medical Encyclopedia

key stimuli- objects of living and inanimate nature biologically significant for animals (see instinctive behavior of animals). Brief psychological dictionary. Rostov-on-Don: PHOENIX. L.A. Karpenko, A.V. Petrovsky, M. G. Yaroshevsky. 1998 ... Great Psychological Encyclopedia

Key irritants- (releasers) - objects, phenomena of animate and inanimate nature that cause specific reactions in animals. It is believed that the ratio of K. r. to the called reaction is strictly predetermined, as the ratio of "key to lock", and the reaction is carried out thanks to ... ... Dictionary of trainer

Key irritants- biologically significant for animals objects of animate and inanimate nature. L.A. Karpenko ...

COMPLEX IRRITANTS- (from lat. complexus connection, combination ...) conditioned signals composed of several separate stimuli (light, sound, tactile). Distinguish simultaneous and consecutive To. If K. r. are reinforced, but their components are not ... ... Encyclopedic Dictionary of Psychology and Pedagogy

Books

Yamal in geopolitical and civilizational dynamics, Zubkov K.I. Materials from the history of the development of the Yamalo-Nenets Autonomous Okrug as a spatial system are published in a collective monograph. Having paid significant attention to the spatial dimension ...
Analysis and synthesis of complex stimuli in complex animals, A. G. Voronin. Leningrad, 1952. State publishing house of medical literature. Publisher's binding. The safety is good. The first chapter of the publication presents a review of the literature on conditioned reflexes ...

Previously, I mainly wrote articles about the internal causes of ailments. We are talking about those diseases that appear as a result of our hectic lifestyle, lack of a sense of proportion and other reasons. Let's look at the problem from the other side. True, the line between external and internal is very conditional ...

So, let's see how weather and climate affect human health. how external stimuli affect us? It turns out that the wind provokes an exacerbation of diseases of the gallbladder and liver, the cold negatively affects the weak kidneys and bladder, the heart and small intestine do not tolerate heat well, dry weather adversely affects the condition of the lungs and large intestine, and humidity has a destructive effect on the pancreas and stomach.

Here are a couple of examples to illustrate the influence of external stimuli on our body.

Last autumn, there were strong winds in the Gomel region for several days. Gusts of wind sometimes reached such force that they ripped off the roofs of houses. And in the same days, the city was “covered” by an epidemic of meningitis. Basically, it concerned children. Meningitis appeared in children due to diseases of the liver and gallbladder. A strong wind provoked an epidemic.

If my article were read by police officers, I would ask them to find a connection between the increased number of crimes and strong winds. The wind exacerbates the painful condition of the gallbladder, and this leads to increased anger. Surely, this circumstance affects the number of domestic crimes.

Winter is coming, and since 95% of the readers of this article have kidney disease, I want to draw your attention to the fact that it is during this period that the kidneys must be especially protected. The main thing is not to overcool. The lack of movement in winter also negatively affects the functioning of the kidneys. Weakened kidneys provoke colds. And don't even expect a flu shot, that's stupid.

Ambulance crews of any department will tell you that the peak of their trips for heart attacks and other heart diseases occurs in the summer.

The place where we live shapes our mentality, affects temperament and character. When moving to another country for permanent residence, know that you will live among those who were born and grew up under the influence of another element. And you will have to adapt both to the place and to the people. In addition to the direct impact of new energies, stress will also affect your health and mentality due to the difference in mentality. No wonder folk wisdom says, "Where I was born, there I fit." After all, it is the energy of your native land that gives you the opportunity to live in harmony with yourself and your countrymen.

For those who are interested in monitoring the biorhythms of organs throughout the year, I long ago compiled a calendar of periods of exacerbations of diseases. Don't forget to follow the automatic monthly updates.