How autumn affects a person. How to deal with autumn blues
Seasonal changes include profound shifts in the body under the influence of changes in nutrition, environmental temperature, radiant solar regime and under the influence of periodic changes in the endocrine glands, mainly associated with animal reproduction. The question of factors external environment, defining seasonal periodicals, is extremely complex and has not yet received full resolution; in the formation of seasonal cycles, shifts in the functions of the sex glands, the thyroid gland, etc., which are very stable in nature, are of great importance. These changes, well established morphologically, are very stable in their sequential development for different species and greatly complicate the analysis of the influence physical factors causing seasonal periodicals.
Seasonal changes in the body include behavioral responses. They consist either in the phenomena of migration and nomadism (see below), or in the phenomena of winter and summer hibernation, or, finally, in a variety of activities for the construction of burrows and shelters. There is a direct relationship between the depth of the holes of some rodents and the winter temperature drop.
Of great importance for the total daily activity of the animal is the lighting regime. Therefore, seasonal periodicals cannot be considered outside the latitudinal distribution of organisms. Figure 22 shows the breeding seasons for birds in different latitudes of the northern and southern hemispheres. One can clearly see the timing of reproduction shifted to earlier months when moving from north to south in the Northern Hemisphere and an almost mirror image of these relationships in the Southern Hemisphere. Similar dependences are also known for mammals, for example, for sheep. Here we mainly consider
physiological changes in the body, occurring in the temperate climate of the middle latitudes of the Northern Hemisphere. The greatest changes in the body during the seasons of the year relate to the blood system, general metabolism, thermoregulation, and partly digestion. Of exceptional importance for boreal organisms is the accumulation of fat as an energy potential spent on maintaining body temperature and muscle activity.
The most noticeable changes in motor activity in different seasons can be observed in diurnal animals, which is undoubtedly related to the lighting regime. These relationships have been best studied in monkeys (Shcherbakova, 1949). When monkeys were kept throughout the year at a constant ambient temperature, the total daily activity depended on the length of daylight hours: an increase in activity took place in May
and June. An increase in total daily activity was observed in December and January. The latter cannot be attributed in any way to the influence of daylight hours and is probably associated with spring manifestations in nature in Sukhumi conditions (Fig. 23).
These studies also found a significant seasonal variation in body temperature in monkeys. The highest temperature in the rectum was observed in June, the lowest - in January. These shifts cannot be explained by changes in temperature in the external environment, since the room temperature remained constant. It is very likely that the effect of radiative cooling took place here, due to the reduced temperature of the walls of the room.
Under natural conditions (Khrustselevsky and Kopylova, 1957), Brandt's voles in Southeastern Transbaikalia show a striking seasonal dynamics of locomotor activity. They have a sharp decrease in activity - exit from holes in January, March, November and December. The reasons for this pattern of behavior are quite complex. They are associated with the nature of the pregnancy of usually very active females, with the timing of sunrise and sunset, high temperatures in summer and low in winter. Daily activity studied under natural conditions is much more complicated and does not always reflect the picture obtained by the researcher using the actographic technique.
Similar complex relationships were discovered (Leontiev, 1957) for Brandt's vole and Mongolian gerbil in the Amur region.
In minks (Ternovsky, 1958), significant changes in motor activity are observed depending on the seasons of the year. The greatest activity takes place in spring and summer, which, apparently, is associated with the length of daylight hours. However, as the temperature drops, activity decreases, as does precipitation. All gregarious ungulates, without exception, have seasonal changes herding, which is pronounced in moose. In the reindeer, herd relations (grouping, following each other) are more noticeable in autumn than in summer or spring (Salgansky, 1952).
Seasonal changes in metabolism (basal metabolism) are best studied. Back in 1930, the Japanese researcher Ishida (Ishida, 1930) found a significant increase in basal metabolism in rats in the spring. These facts have since been confirmed by numerous studies (Kayser, 1939; Sellers, Scott a. Thomas, 1954; Kocarev, 1957; Gelineo a. Heroux, 1962). It has also been established that in winter the basal metabolism in rats is much lower than in summer.
Very striking seasonal changes in basal metabolism are found in fur-bearing animals. Thus, the basal metabolism in arctic foxes in summer compared with winter is increased by 34%, and in silver-black foxes - by 50% (Firstov, 1952). These phenomena are undoubtedly connected not only with the seasonal Cycle, but also with the overheating that takes place in the summer (see Chap. V) and have been noted by various researchers in arctic foxes, raccoon dogs (Slonim, 1961). In the gray rats under the conditions of the Arctic, an increase in metabolism in the spring and a decrease in the autumn were also found.
Study of chemical thermoregulation in polar species (arctic foxes, foxes, hares) wintering in the conditions of the Leningrad Zoological Garden (Isaakyan and Akchurin,
1953) showed, under the same conditions of keeping, sharp seasonal changes in chemical thermoregulation in foxes and raccoon dogs and the absence of seasonal changes in arctic foxes. This is especially pronounced in autumn months when the animals are in summer fur. The authors explain these differences by the responses to changes in lighting that are specific to Arctic foxes. It is at the foxes in autumn period there is practically no chemical thermoregulation, although the insulating layer of wool had not yet become winter by this time. Obviously, these reactions, specific for polar animals, cannot be explained only by the physical properties of the skin: they are the result of complex specific features of the nervous and hormonal mechanisms of thermoregulation. These reactions in polar forms are combined with thermal insulation (Scholander and co-workers, see p. 208).
A large amount of material on seasonal changes in gas exchange in various rodent species (Kalabukhov, Ladygina, Maizelis and Shilova, 1951; Kalabukhov, 1956, 1957; Mikhailov, 1956; Skvortsov, 1956; Chugunov, Kudryashov and Chugunova, 1956, etc.) showed that non-sleeping rodents can observe an increase in metabolism in autumn and a decrease in winter. The spring months are characterized by an increase in metabolism, and the summer months by a relative decrease. The same data on a very large material were obtained for the common vole and bank vole in the Moscow region.
Schematically, the seasonal curve of metabolic changes in non-hibernating mammals can be represented as follows. The highest level of metabolism is observed in spring during the period of sexual activity, when animals, after a winter food restriction, begin active food-procuring activities. In summer, the exchange level again decreases slightly due to high temperature, and in autumn it rises slightly or stays at the summer level, gradually decreasing towards winter. In winter, there is a slight decrease in basal metabolism, and by spring it again rises sharply. This general pattern of changes in the level of gas exchange throughout the year for certain types and can vary considerably under individual conditions. This is especially true for farm animals. So, the main metabolism in non-lactating cows (Ritzman a. Benedict, 1938) in the summer months, even on the 4-5th day of fasting, was higher than in winter and autumn. In addition, it is very important to note that the spring increase in metabolism in cows is not associated with pregnancy and lactation, with the conditions in the stall or on the pasture. With stall keeping, gas exchange in spring is higher than with grazing in autumn, although grazing itself increases gas exchange at rest throughout the pasture season (Kalitaev, 1941).
In summer, gas exchange in horses (at rest) increases by almost 40% compared to winter. At the same time, the content of erythrocytes in the blood also increases (Magidov, 1959).
Very large differences (30-50%) in energy metabolism in winter and summer are observed in reindeer (Segal, 1959). In Karakul sheep, despite the course of pregnancy in winter, there is a significant decrease in gas exchange. Cases of a decrease in metabolism in winter in reindeer and Karakul sheep are undoubtedly associated with food restrictions in winter.
Changes in basal metabolism are also accompanied by shifts in chemical and physical thermoregulation. The latter is associated with an increase in thermal insulation (insulation) wool and feather covers in winter. The decrease in thermal insulation in summer affects both the level critical point(see ch. V), and on the intensity of chemical thermoregulation. So, for example, the values of heat transfer in summer and winter in different animals are: for squirrels, as 1: 1; in a dog 1: 1.5; in a hare 1: 1.7. Depending on the seasons of the year, heat transfer from the surface of the body changes significantly due to the processes of molting and overgrowing with winter wool. In birds, the electrical activity of the skeletal muscles (due to the absence of non-shivering thermogenesis) does not change in winter and summer; in mammals, such as the gray rat, these differences are very significant (Fig. 25).
Seasonal changes in the critical point of metabolism were found in recent times in polar animals in Alaska (Irving, Krogh a. Monson, 1955) - in the red fox they are + 8 ° in summer, -13 ° in winter; for squirrels - in summer and winter + 20 ° С; at the porcupine (Erethizoon dorsatum) +7°C in summer and -12°C in winter. The authors also associate these changes with seasonal changes in the thermal insulation of the fur.
The metabolism of polar animals in winter, even at a temperature of -40 ° C, increases relatively slightly: in the fox and polar porcupine - no more than 200% of the metabolic level at the critical point, in squirrels - about 450-500%. Similar data were obtained in the conditions of the Leningrad Zoo on arctic foxes and foxes (Olnyanskaya and Slonim, 1947). A shift in the critical point of metabolism from +30°C to +20°C was observed in the gray rat in winter (Sinichkina, 1959).
Study of seasonal changes in gas exchange in steppe lemmings ( Lagurus lagurus) showed (Bashenina, 1957) that in winter their critical point, unlike other species of voles, is unusually low - about 23 ° C. The critical point of metabolism in midday gerbils shifts in different seasons, while in Grebenshchikov it remains constant (Mokrievich, 1957 ).
The highest values of oxygen consumption at environmental temperatures from 0 to 20°C were observed in yellow-throated mice caught in summer, and the lowest in winter (Kalabukhov, 1953). The data for mice caught in autumn were in the middle position. The same work made it possible to discover very interesting changes in the thermal conductivity of wool (taken from animals and dried skins), which strongly increases in summer and decreases in winter. Some researchers are inclined to attribute to this circumstance a leading role in changes in metabolism and chemical thermoregulation during different seasons of the year. Of course, such dependences cannot be denied, but also in laboratory animals (white rats) there is a pronounced seasonal dynamics even at constant environmental temperatures (Isaakyan and Izbinsky, 1951).
In experiments on monkeys and wild carnivores, it was found (Slonim and Bezuevskaya, 1940) that chemical thermoregulation in spring (April) is more intense than in autumn (October), despite the fact that the ambient temperature was the same in both cases (Fig. 26) . Obviously, this is the result of the previous influence of winter and summer and the corresponding changes.
in the endocrine systems of the body. In summer, there is a decrease in the intensity of chemical thermoregulation, in winter - an increase.
Peculiar seasonal changes in chemical thermoregulation were found in the yellow ground squirrel, which enters winter and summer hibernation, and the non-hibernating fine-clawed ground squirrel (Kalabukhov, Nurgel'dyev and Skvortsov, 1958). In the thin-toed ground squirrel, seasonal changes in thermoregulation are more pronounced than in the yellow ground squirrel (of course, in the waking state). In winter, the exchange of fine-clawed ground squirrel is sharply increased. In summer, the yellow ground squirrel's chemical thermoregulation is disturbed already at + 15-5 ° C. Seasonal changes in thermoregulation are almost absent in it and are replaced by long winter and summer hibernation (see below). Seasonal changes in thermoregulation are equally poorly expressed in the tarbagan, which falls into summer and winter hibernation.
Comparison of seasonal changes in chemical thermoregulation and the biological cycle of animals (N.I. Kalabukhov et al.) showed that seasonal changes are weakly expressed both in hibernating species and in species that spend the winter in deep burrows and are little exposed to low outdoor temperatures ( e.g. a large gerbil).
Thus, seasonal changes in thermoregulation are reduced mainly to an increase in thermal insulation in winter, a decrease in the intensity of the metabolic reaction (chemical thermoregulation) and a shift in the critical point to a zone of lower environmental temperatures.
The thermal sensitivity of the body also changes somewhat, which is apparently associated with a change in coat. Such data were established by N. I. Kalabukhov for arctic foxes (1950) and yellow-throated mice (1953).
In gray rats living in the middle lane, the preferred temperature in winter is from 21 to 24 ° C, in summer - 25.9-28.5 ° C, in autumn - 23.1-26.2 ° C and in spring - 24.2 ° C (Sinichkina , 1956).
Under natural conditions in wild animals, seasonal changes in oxygen consumption and heat production can largely depend on feeding conditions. However, there is no experimental confirmation yet.
The hematopoietic function changes significantly according to the seasons of the year. The most striking shifts in this regard are observed in humans in the Arctic. In spring, one can observe a large increase in the number of erythrocytes and hemoglobin (Hb) blood, which is associated with the transition from the polar night to the polar day, i.e., with changes in insolation. However, even in conditions of sufficient insolation in the Tien Shan mountains, a person has a somewhat reduced amount of hemoglobin in the blood in winter. A sharp increase in Hbobserved in spring. The number of erythrocytes decreases in spring and increases in summer (Avazbakieva, 1959). In many rodents, for example, in gerbils, the content of erythrocytes decreases in summer, and increases in spring and autumn (Kalabukhov et al., 1958). The mechanism of these phenomena is still unclear. There are also changes in nutrition, vitamin metabolism, ultraviolet radiation, etc. The influence of endocrine factors is also not excluded, and especially important role belongs to the thyroid gland, which stimulates erythropoiesis.
Highest value in maintaining the seasonal rhythm have hormonal shifts, representing both independent cycles of endogenous origin, and associated with exposure the most important factor environment - lighting mode. At the same time, a scheme of relationships between the hypothalamus - the pituitary gland - the adrenal cortex is already being outlined.
Seasonal changes in hormonal relations have been revealed in wild animals under natural conditions using the example of changes in the weight of the adrenal glands (which, as is known, play an important role in the adaptation of the body to specific and non-specific conditions of "tension" - stress).
The seasonal dynamics of the weight and activity of the adrenal glands has a very complex origin and depends both on the actual “stress” in connection with living conditions (nutrition, environmental temperature) and on reproduction (Schwartz et al., 1968). In this regard, data on changes in the relative weight of the adrenal glands in non-breeding field mice are of interest (Fig. 27). During the period of enhanced nutrition and optimal temperature conditions, the weight of the adrenal glands increases dramatically. In autumn, with cooling, this weight begins to decrease, but with the establishment of snow cover it stabilizes. In the spring (April), an increase in the weight of the adrenal glands begins in connection with the growth of the organism and puberty (Shvarts, Smirnov, Dobrinsky, 1968).
The morphological picture of the thyroid gland in many species of mammals and birds is subject to significant seasonal changes. In the summer, there is a disappearance of the follicle colloid, a decrease in the epithelium, and a decrease in the weight of the thyroid gland. In winter, the reverse relationship takes place (Riddle, Smith a. Benedict, 1934; Watzka, 1934; Miller, 1939; Hoehn, 1949).
The seasonal variability in the function of the thyroid gland in the reindeer is just as clearly expressed. In May and June, its hyperfunction is observed with increased secretory activity of epithelial cells. In winter, especially in March, the secretory activity of these cells ceases. Hyperfunction is accompanied by a decrease in the volume of the gland. Similar data were obtained in sheep, but the pattern was much less pronounced.
At present, there are numerous data indicating the presence of stable seasonal fluctuations in the content of thyroxine in the blood. Most high level thyroxine (determined by the content of iodine in the blood) is observed in May and June, the lowest - in November, December and January. Studies have shown (Sturm a. Buchholz, 1928; Curtis, Davis a. Philips, 1933; Stern, 1933) there is a direct parallelism between the intensity of thyroxine production and the level of gas exchange in humans during the seasons of the year.
There are indications of a close relationship between body cooling and the production of thyroid hormone and pituitary thyroid-stimulating hormone (Uotila, 1939; Voitkevich, 1951). These relationships are also very important in the formation of seasonal periodicals.
Apparently, a significant role in seasonal periodicals belongs to such a non-specific hormone as adrenaline. A large body of evidence suggests that adrenaline promotes better acclimatization to both heat and cold. Combinations of thyroxine and cortisone preparations are especially effective (Hermanson a. Hartmann, 1945). Animals well acclimatized to cold have a high content of ascorbic acid in the adrenal cortex (Dougal a. Fortier, 1952; Dugal, 1953).
Adaptation to low ambient temperature is accompanied by an increase in the content of ascorbic acid in tissues, an increase in the content of hemoglobin in the blood (Gelineo and Raiewskaya, 1953; Raiewskaya, 1953).
Recently accumulated great material characterizing seasonal fluctuations in the content of corticosteroids in the blood and the intensity of their release during incubation of the adrenal cortex in vitro.
The role of the lighting regime in the formation of the seasonal rhythm is recognized by the vast majority of researchers. Lighting, as was established in the middle of the last century (Moleschott, 1855), has a significant effect on the intensity of oxidative processes in the body. Gas exchange in humans and animals under the influence of lighting increases (Moleschott u. Fubini, 1881; Arnautov and Weller, 1931).
However, until recently, the question of the effect of illumination and darkening on gas exchange in animals with in different ways life and only when studying the effect of illumination intensity on gas exchange in monkeys (Ivanov, Makarova and Fufacheva, 1953) did it become clear that it is always higher in the light than in the dark. However, these changes were not the same for all species. In hamadryas, they were most pronounced, followed by rhesus monkeys, and the effect of illumination had the least effect on green monkeys. The differences could only be understood in connection with the ecological features of the existence of the listed species of monkeys in nature. So, the hamadryas monkeys are the inhabitants of the treeless highlands of Ethiopia; rhesus macaques are inhabitants of the forest and agricultural cultural areas, and green monkeys are dense tropical forests.
The reaction to illumination appears relatively late in ontogeny. So, for example, in newborn kids, the increase in gas exchange in the light compared to the dark is very small. This reaction increases significantly by the 20-30th day and even more by the 60th (Fig. 28). It can be assumed that in animals with daytime activity the reaction to the intensity of illumination has the character of a natural conditioned reflex.
In the nocturnal loris lemurs, an inverse relationship has been observed. Their gas exchange was increased
in the dark and reduced when illuminated during the determination of gas exchange in the chamber. The decrease in gas exchange in the light reached 28% in lorises.
The facts of the influence of prolonged illumination or darkening on the organism of mammals were established by an experimental study of the light regime (daylight hours) in connection with the seasonal effects of illumination. experimental study A large number of studies have been devoted to the influence of daylight hours on seasonal periodicals. Most of the data collected for birds, where the increase in daylight hours is a factor stimulating sexual function (Svetozarov and Shtreich, 1940; Lobashov and Savvateev, 1953),
The facts obtained indicate both the value of the total length of daylight hours and the value of the change in the phases of illumination and dimming.
good criterion The influence of the lighting regime and the duration of daylight hours for mammals is the course of ovulation. However, it is precisely in mammals that such a direct effect of light on ovulation in all species without exception cannot be established. Numerous data obtained on rabbits (Smelser, Walton a. Whethem, 1934), guinea pigs (Dempsey, Meyers, Young a. Jennison, 1934), mice (Kirchhof, 1937) and ground squirrels (Welsh, 1938) show that keeping animals in complete darkness has no effect on ovulation.
In special studies, “winter conditions” were simulated by cooling (from -5 to +7 ° C) and keeping in complete darkness. These conditions did not affect the intensity of reproduction in the common vole. ( Microtus arvalis) and developmental speed of the young. Consequently, the combination of these main environmental factors, which determine the physical side of seasonal influences, cannot explain the winter suppression of the intensity of reproduction, at least for rodents of this species.
In carnivores, a significant effect of light on the function of reproduction was found (Belyaev, 1950). A decrease in daylight hours leads to an earlier maturation of fur in minks. Changing the temperature regime does not have any effect on this process. In martens, additional lighting causes the onset of the mating period and the birth of cubs 4 months earlier than usual. Changing the lighting regime does not affect the basal metabolism (Belyaev, 1958).
However, seasonal periodicals cannot be imagined only as a result of the influence of environmental factors, as indicated by a large number of experiments. In this regard, the question arises whether there is a seasonal periodicals in animals isolated from the influence of natural factors. In dogs that were kept in a heated room under artificial lighting throughout the year, it was possible to observe the seasonal periodicity characteristic of dogs (Magnonet Guilhon, 1931). Similar facts were found in experiments on laboratory white rats (Izbinsky and Isahakyan, 1954).
Another example of the extreme durability of seasonal periodicals concerns animals brought from the southern hemisphere. So, for example, the Australian ostrich in the Askania Nova reserve lays eggs in our winter, despite the severe frost, right in the snow in the season corresponding to summer in Australia (M. M. Zavadovsky, 1930). The Australian dingo breeds at the end of December. Although these animals, like ostriches, have been bred in the northern hemisphere for many decades, no change in their natural seasonal rhythm is observed.
In humans, the change in metabolism proceeds according to the same pattern as in non-sleeping animals. There are observations obtained in a natural setting with an attempt to pervert the natural seasonal cycle. The simplest way of such a perversion and the most reliable facts are obtained in the study of transfers from one locality to another. So, for example, moving in December - January from the middle zone of the USSR to the southern one (Sochi, Sukhumi) causes the effect of increasing the reduced "winter" exchange during the first month of stay there due to the new conditions of the south. Upon returning to the north in spring, a secondary spring increase in exchange occurs. Thus, during a winter trip to the south, one can observe two spring rises in the metabolic rate in the same person during the year. Consequently, a perversion of the seasonal rhythm also takes place in humans, but only under conditions of changes in the entire complex of natural environmental factors (Ivanova, 1954).
Of particular interest is the formation of seasonal rhythms in humans in the Far North. Under these conditions, especially during life at small stations, the seasonal periodicals are sharply disturbed. Insufficient muscular activity due to the restriction of walks, often impossible in the conditions of the Arctic, creates an almost complete loss of the seasonal rhythm (Slonim, Ol'nyanskaya, Ruttenburg, 1949). Experience shows that the creation of comfortable settlements and cities in the Arctic restores it. The seasonal rhythm in humans is to some extent a reflection not only of seasonal factors common to the entire living population of our planet, but, like the daily rhythm, is a reflection of the social environment that affects humans. Large cities and towns in the Far North with artificial lighting, with theaters, cinemas, with all the rhythm of life characteristic of modern man,
create such conditions under which the seasonal rhythm manifests itself normally beyond the Arctic Circle and is revealed in the same way as in our latitudes (Kandror and Rappoport, 1954; Danishevsky, 1955; Kandror, 1968).
In the conditions of the North, where there is a large lack of ultraviolet radiation in winter, there are significant metabolic disorders, mainly phosphorus metabolism, and a lack of vitamin D (Galanin, 1952). These phenomena are especially hard on children. According to German researchers, in winter there is a so-called "dead zone", when the growth of children completely stops (Fig. 29). Interestingly, in the Southern Hemisphere (Australia), this phenomenon occurs during the months corresponding to summer in the Northern Hemisphere. Now additional ultraviolet irradiation is considered as one of the most important methods of correcting the normal seasonal rhythm in northern latitudes. Under these conditions, we have to talk not so much about the seasonal rhythm, but about the specific lack of this natural necessary factor.
Seasonal periodicals are also of great interest to animal husbandry. Scientists are now inclined to believe that a significant part of the seasonal periods should be changed by the conscious influence of man. It is primarily about the seasonal diet. If for wild animals the lack of nutrition sometimes leads to the death of a significant number of individuals, to a decrease in the number of their representatives in a given area, then in relation to cultivated agricultural animals this is completely unacceptable. The nutrition of farm animals cannot be based on seasonal resources, but must be supplemented on the basis of human economic activity.
Seasonal changes in the body of birds are closely related to their characteristic flight instinct and are based on changes in the energy balance. However, despite the flights, birds show both seasonal changes in chemical thermoregulation and changes in the thermal insulation properties of the feather cover (insulation).
Metabolic changes in the house sparrow are well expressed ( Passer domesticus), the energy balance of which at low temperatures is maintained by greater heat production in winter than in summer. The results obtained from the measurement of food intake and metabolism show a flattened type of chemical thermoregulation curve, usually found when heat production is estimated from food intake over several days, and not from oxygen consumption in a short-term experiment.
Recently, it has been found that the maximum heat production in passerines is higher in winter than in summer. In grosbeaks, pigeons columba livia and starlings Sturnus vulgaris the survival time during cold periods in winter was longer mainly as a result of the increased ability to maintain higher heat production. The duration of the period before death is also affected by the state of plumage - molting and the duration of captivity, but the seasonal effect is always pronounced. Those who are IB bird cage food intake in winter increased by 20-50%. But winter food intake in caged finches ( Fringilla montefringilla) and in wild house sparrows did not increase (Rautenberg, 1957).
Significant nocturnal hypothermia, observed in winter in freshly caught birds, is absent in the grosbeak and black-headed tit. Irving (Irving, 1960) concluded that, on cold nights, northern birds cool below their daytime body temperature by about the same extent as birds in temperate regions.
The increase in plumage weight observed in some birds during winter suggests a thermal insulating adaptation that could partially offset changes in cold metabolism. However, Irving's research on several species of wild birds in winter and summer, as well as Davis (Davis, 1955) and Hart (Hart, 1962) provide little evidence for the assumption that the increase in metabolism with a 1° drop in temperature was different in these seasons. It was found that the heat production in pigeons, measured at 15°C, was lower in winter than in summer. However, the magnitude of these seasonal changes was small and no shifts were observed in the range of critical temperatures. Data on shifts in the critical temperature level were obtained for the cardinal ( Richmonda cardinalis) ( lawson, 1958).
Walgren (Wallgren, 1954) studied energy metabolism in yellow bunting ( Emberiza citrinella) at 32.5°C and at -11°C at different times of the year. Exchange at rest showed no seasonal changes; at -11 0 C in June and July, the exchange was significantly higher than in February and March. This insulative adaptation is partly explained by the greater thickness and "fluffing" of plumage and greater vasoconstriction in winter (since the plumage was most dense in September - after molting, and the maximum metabolic changes - in February).
Theoretically, changes in plumage can explain the decrease in lethal temperature by about 40 ° C.
Studies conducted on the black-headed tit ( Parus atricapillus), also indicate the presence of low heat production as a result of thermal insulation adaptation in winter. The pulse rate and respiration rate had seasonal shifts, and the decrease was greater in winter at 6°C than in summer. The critical temperature at which respiration sharply increased also shifted to a lower level in winter.
The increase in basal metabolism at thermoneutral temperatures, which is pronounced in mammals and birds exposed to cold for several weeks, does not play a significant role during winter adaptation. The only evidence of a significant seasonal variation in basal metabolism has been obtained in house sparrows, but there is no reason to assume that it plays any significant role in birds living in the wild. Most of the studied species do not show any changes at all. King and Farner (King a. Farrier, 1961) indicate that a high intensity of basal metabolism in winter would be unfavorable, since the bird would need to increase the consumption of its energy reserves at night.
The most characteristic seasonal shifts in birds are their ability to change their thermal insulation and the amazing ability to maintain a higher level of heat production in cold conditions. Based on the measurement of food intake and excretion at different temperatures and photoperiods, estimates of energy requirements for existence and productive processes were made at different times of the year. For this purpose, the birds were housed in individual cages where their metabolized energy (maximum energy influx minus excretion energy at different temperatures and photoperiods) was measured. The smallest metabolized energy required for existence at certain temperatures and photoperiods of the test is called "existence energy". Its correlation with temperature is shown on the left side of Figure 30. Potential energy is the maximum metabolized energy measured at a temperature corresponding to the lethal limit, which is the lowest temperature at which a bird can support its body weight. Productivity energy is the difference between potential energy and existence energy.
The right side of Figure 30 shows different energy categories calculated for different seasons from average outdoor temperatures and photoperiods. For these calculations, it is assumed that the maximum metabolized energy is found in cold conditions, as well as for productive processes at higher temperatures. In the house sparrow, potential energy is subject to seasonal changes due to seasonal changes in survival limits. The energy of existence also changes according to the average outdoor temperature. Due to seasonal changes in potential energy and energy of existence, the energy of productivity remains constant throughout the year. Some authors point out that the ability of the house sparrow to live in the far northern latitudes is due to its ability to stretch its maximum energy balance throughout the winter and metabolize as much energy during a short daytime photoperiod in winter as during long photoperiods in summer.
At the white-throated sparrow (Z. albicallis) and the junkoJ. hue- malls) with a 10-hour photoperiod, the amount of metabolized energy is less than with a 15-hour photoperiod, which is a serious disadvantage of winter time (Seibert, 1949). These observations were compared with the fact that both species migrate south in winter.
Unlike the house sparrow, the tropical blue-black finch ( Votatinia jacarina) could maintain energy balance down to about 0°C for a 15-hour photoperiod and up to 4°C for a 10-hour photoperiod. The photoperiod limited energy in more when the temperature drops, what is the difference between these birds and the house sparrow. Due to the influence of the photoperiod, the potential energy was lowest in winter, when the energy of existence is highest. Consequently, the productivity energy was also the lowest at that time of the year. These physiological characteristics do not allow this species exist in winter in northern latitudes.
Although the energy requirements for thermoregulation in the cold season turn out to be maximum, various types of bird activity are apparently distributed evenly throughout the year, and therefore the cumulative effects are negligible. The distribution of established energy demands for various activities throughout the year is best described for three sparrows. S. arborea ( West, 1960). In this species the largest number energy productivity potentially accounted for during daylight saving time. Therefore, activities that require energy expenditure, such as migration, nesting and molting, are evenly distributed between April and October. The additional cost of free existence is an unknown that may or may not increase the theoretical potential. However, it is quite possible that potential energy can be used at any time of the year, at least for short periods - for the duration of the flight.
Seasonal climate changes are reflected in the work of the body. Let's take a look at how to deal with this.
The emotional state directly depends on the weather, so in autumn and winter, when the days are getting shorter and there are fewer sunny days, it is easy to fall into.
How to deal with autumn blues
The main thing is not to focus on bad mood. Vitamins (fruits, vegetables), and physical activity will come to the rescue. Daily walks are enough to keep the body in good shape: 30 minutes before work and 1.5 hours after - this is an example :) Just get off one stop earlier or walk to the metro. This is especially important if you spend most of your working day sitting at a computer.
Human biorhythms in autumn
Due to the reduction of daylight hours, the body is “lost in time” and experiences stress. As a result, seasonal changes appear - weakness, drowsiness and apathy.
What to do: There are days when it is absolutely impossible to get out of bed. And if you succeed, then the whole day uncontrollably pulls you to sleep. An effective way to wake up is to slowly and deeply inhale 10 times, do gymnastics and drink a glass of freshly squeezed vegetable or fruit juice. Blood will carry oxygen to all cells of the body, and glucose will activate brain activity.
Vigor and good condition also depend on proper lymph flow. Lymph moves through the vessels and capillaries due to muscle contraction, freeing the body of toxins. You can stimulate the lymph flow with massage. When taking a shower, rub your body from the bottom up - from the feet to the hips, from the bones to the shoulders, from the waist to the neck.
Diseases of the digestive system
The body intensively prepares for winter and accumulates fat reserves. Many at this time have a constant feeling of hunger, and someone suffers from gastric disorders.
Prevention
To avoid exacerbation of gastrointestinal diseases, exclude spicy, salty, fatty foods, carbonated drinks and spices from the diet. It is recommended to eat often, but in small portions. Steam cooking is best. If the stomach is particularly sensitive, switch to pureed foods for a while. In addition, it is recommended to eat a handful of nuts and dried fruits (previously soaked in water overnight), they have a beneficial effect on work digestive system, if there is in moderation, of course.
Heart diseases
Like the whole body, the cardiovascular system in the autumn works in an enhanced mode. Blood pressure fluctuations can be disturbing, and cores are generally at risk.
Prevention
You need to limit yourself in certain foods. For example, it is strongly recommended to give up salt and salty foods in general - herring, caviar, olives, cucumbers, dried fish, etc. They contribute to the thickening of the blood and can provoke a stroke or heart attack. But you can eat plenty of nuts, dried fruits, vegetables - they contain substances that strengthen the heart muscle. It is recommended to start the day with a glass of water and a healthy breakfast - fruit or fruit salad.
One of the fundamental properties of living nature is the cyclicity of most of the processes occurring in it. Between movement celestial bodies and living organisms on Earth there is a connection.
Living organisms not only capture the light and heat of the sun and moon, but also have various mechanisms that accurately determine the position of the Sun, respond to the rhythm of the tides, the phases of the moon and the movement of our planet. They grow and reproduce in a rhythm that is timed to the length of the day and the change of seasons, which in turn is determined by the movement of the Earth around the Sun. The coincidence of the phases of the life cycle with the season to which they are adapted has crucial for the existence of the species. In the process of historical development, cyclical phenomena occurring in nature were perceived and assimilated by living matter, and organisms developed the ability to periodically change their physiological state.
The uniform alternation in time of any state of the body is called biological rhythm.
Distinguish between external (exogenous), having a geographical nature and following cyclic changes in the external environment, and internal (endogenous), or physiological, rhythms of the body.
External rhythmsExternal rhythms are of a geographical nature, associated with the rotation of the Earth relative to the Sun and the Moon relative to the Earth.
Many environmental factors on our planet, primarily the light regime, temperature, air pressure and humidity, atmospheric electromagnetic field, sea tides, etc., naturally change under the influence of this rotation. Living organisms are also affected by such cosmic rhythms as periodic changes solar activity. The Sun is characterized by an 11-year-old and whole line other cycles. Changes in solar radiation have a significant impact on the climate of our planet. In addition to the cyclical impact of abiotic factors, external rhythms for any organism are regular changes in activity, as well as the behavior of other living beings.
Internal, physiological, rhythmsInternal, physiological, rhythms arose historically. Not a single physiological process in the body is carried out continuously. Rhythm was found in the processes of DNA and RNA synthesis in cells, in the synthesis of proteins, in the work of enzymes, and in the activity of mitochondria. Cell division, muscle contraction, the work of endocrine glands, heartbeat, respiration, excitability of the nervous system, i.e., the work of all cells, organs and tissues of the body obeys a certain rhythm. Each system has its own period. This period can be changed by the actions of environmental factors only within narrow limits, and for some processes it is practically impossible. This rhythm is called endogenous.
The internal rhythms of the organism are subordinated, integrated into an integral system and ultimately act as a general periodicity of the organism's behavior. The body, as it were, counts time, rhythmically exercising its physiological functions. For both external and internal rhythms, the onset of the next phase primarily depends on time. Hence, time acts as one of the most important environmental factors to which living organisms must respond, adapting to external cyclic changes in nature.
Changes in the vital activity of organisms often coincide in period with external, geographical cycles. Among them are such as adaptive biological rhythms - daily, tidal, equal to the lunar month, annual. Thanks to them, the most important biological functions of the organism (nutrition, growth, reproduction, etc.) coincide with those most favorable for this time of day and year.
Daily mode. Twice a day, at dawn and dusk, the activity of animals and plants on our planet changes so dramatically that it often leads to an almost complete, figuratively speaking, change. actors". This is the so-called daily rhythm, due to the periodic change in illumination due to the rotation of the Earth around its axis. In green plants, photosynthesis occurs only during daylight hours. In plants, the opening and closing of flowers, the raising and lowering of leaves, the maximum intensity of respiration, the rate of growth of the coleoptile, etc., are often timed to a certain time of day.
note in circles show the approximate time of opening and closing of flowers in different plants
Some species of animals are active only in sunlight, while others, on the contrary, avoid it. Differences between diurnal and nocturnal lifestyles are complex, and are associated with a variety of physiological and behavioral adaptations that have been developed in the process of evolution. Mammals are usually more active at night, but there are exceptions, such as humans: human vision, as well as great apes, is adapted to daylight. Over 100 physiological functions affected by daily periodicity have been noted in humans: sleep and wakefulness, changes in body temperature, heart rate, depth and frequency of breathing, volume and chemical composition urine, sweating, muscular and mental performance, etc. Thus, most animals are divided into two groups of species - daily and night, practically never seen each other.
diurnal animals ( most of birds, insects and lizards) go to sleep at sunset, and the world is filled with nocturnal animals (hedgehogs, bats, owls, most cats, grass frogs, cockroaches, etc.). There are species of animals with approximately the same activity both during the day and at night, with alternating short periods of rest and wakefulness. This rhythm is called polyphasic(a number of predators, many shrews, etc.).
The daily rhythm is clearly seen in the life of the inhabitants of large water systems - oceans, seas, large lakes. Zooplankton make daily vertical migrations, rising to the surface at night and descending during the day. Following zooplankton, larger animals that feed on them move up and down, and even larger predators follow them. It is believed that the vertical movements of planktonic organisms occur under the influence of many factors: light, temperature, water salinity, gravity, and finally, simply hunger. However, according to most scientists, illumination is still primary, since its change can cause a change in the reaction of animals to gravity.
In many animals, the daily periodicity is not accompanied by significant deviations in physiological functions, but is manifested mainly by changes in motor activity, for example, in rodents. The most clearly physiological changes during the day can be traced in bats. During their daytime dormancy in summer, many of the bats behave like poikilothermic animals. The temperature of their body at this time practically coincides with the temperature of the environment. Pulse, respiration, excitability of the sense organs are sharply reduced. To take off, a disturbed bat warms up for a long time due to chemical heat production. In the evening and at night, they are typical homoiothermic mammals with high body temperature, active and precise movements, and a quick reaction to prey and enemies.
Periods of activity in some species of living organisms are confined to a strictly defined time of day, in others they can shift depending on the situation. For example, the activity of black beetles or desert woodlice shifts to different times of the day depending on the temperature and humidity on the soil surface. They emerge from their burrows early in the morning and evening (two-phase cycle), or only at night (single-phase cycle), or throughout the day. Another example. Opening of saffron flowers depends on temperature, dandelion inflorescences on light: on a cloudy day, the baskets do not open. Endogenous circadian rhythms from exogenous ones can be distinguished experimentally. With complete constancy of external conditions (temperature, illumination, humidity, etc.), many species continue to maintain cycles for a long time, close in period to the daily one. Thus, in Drosophila, such an endogenous rhythm has been observed for tens of generations. Consequently, living organisms adapted to perceive fluctuations in the external environment and adjusted their physiological processes accordingly. This happened mainly under the influence of three factors - the rotation of the Earth in relation to the Sun, the Moon and the stars. These factors, superimposed on each other, were perceived by living organisms as a rhythm close to, but not exactly corresponding to, a 24-hour period. This was one of the reasons for some deviation of endogenous biological rhythms from the exact daily period. These endogenous rhythms are called circadian(from lat. circa - about and dies - day, day), i.e., approaching the daily rhythm.
In different species and even in different individuals of the same species, circadian rhythms, as a rule, differ in duration, but under the influence of the correct alternation of light and darkness, they can become equal to 24 hours. So, if flying squirrels (Pebromys volans) are kept in absolute darkness continuously, then all they wake up and lead an active lifestyle at first simultaneously, but soon at different times, and at the same time each individual maintains its own rhythm. When the correct alternation of day and night is restored, the periods of sleep and wakefulness of the flying squirrels become synchronous again. Hence the conclusion that an external stimulus (the change of day and night) regulates innate circadian rhythms, bringing them closer to a 24-hour period.
The stereotype of behavior determined by the circadian rhythm facilitates the existence of organisms with diurnal changes in the environment. At the same time, when plants and animals are dispersed, they enter geographical conditions with a different rhythm of day and night, a strong stereotype can be unfavorable. The dispersal capabilities of certain types of living organisms are often limited by the deep fixation of their circadian rhythms.
In addition to the Earth and the Sun, there is another celestial body, the movement of which noticeably affects the living organisms of our planet - this is the Moon. Among the most diverse peoples, there are signs that speak of the influence of the moon on the productivity of crops, natural meadows and pastures, and the behavior of humans and animals. Periodicity equal to the lunar month, as an endogenous rhythm was found in both terrestrial and aquatic organisms. In confinement to certain phases of the moon, the periodicity is manifested in the swarming of a number of chironomid mosquitoes and mayflies, the reproduction of Japanese crinoids and polychaete palolo worms (Eunice viridis). So, in the unusual process of reproduction of the palolo marine polychaete worms that live in the coral reefs of the Pacific Ocean, the phases of the moon play the role of clocks. The germ cells of worms mature once a year at about the same time - at a certain hour. certain day when the moon is in its last quarter. The back of the worm's body, stuffed with germ cells, breaks off and floats to the surface. The eggs and sperm are released and fertilization occurs. Upper half of the body left in the burrow coral reef, by the next year again builds up the lower half with sex cells. Periodic changes in the intensity of moonlight during the month affects the reproduction of other animals. The beginning of the two-month pregnancy of the giant forest rats of Malaysia usually falls on the full moon. It is possible that bright moonlight stimulates conception in these nocturnal animals.
Periodicity equal to a lunar month was found in a number of animals in response to light and weak magnetic fields, in the rate of orientation. The opinion is expressed that the periods of maximum emotional uplift in people fall on the full moon; The 28-day menstrual cycle of women may have been inherited from the ancestors of mammals, in which body temperature also changed synchronously with the change in the phases of the moon.
Tidal rhythms. The influence of the Moon primarily affects the life of aquatic organisms in the seas and oceans of our planet, is associated with tides, which owe their existence to the joint attraction of the Moon and the Sun. The movement of the Moon around the Earth leads to the fact that there is not only a daily rhythm of the tides, but also a monthly one. The tides reach their maximum height about once every 14 days, when the Sun and Moon are in a straight line with the Earth and have the maximum impact on the waters of the oceans. The rhythm of the tides most strongly affects the organisms that live in coastal waters. The alternation of tides for living organisms is more important here than the change of day and night, due to the rotation of the Earth and the inclined position of the earth's axis. The life of organisms living primarily in the coastal zone is subordinated to this complex rhythm of ebbs and flows. Thus, the physiology of the gruni fish, which lives off the coast of California, is such that at the highest night tides they are washed ashore. Females, burying their tail in the sand, lay their eggs, then the males fertilize them, after which the fish return to the sea. With the retreat of water, fertilized eggs go through all stages of development. The release of fry occurs in half a month and is timed to coincide with the next high tide.
Seasonal periodicity is one of the most common phenomena in living nature. The incessant change of the seasons, due to the rotation of the Earth around the Sun, always delights and amazes a person. In spring, all life awakens from a deep sleep, as the snow melts and the sun shines brighter. Buds burst and young foliage blooms, young animals crawl out of their holes, insects and birds returning from the south scurry about in the air. The change of seasons most noticeably occurs in temperate zones and northern latitudes, where the contrast of meteorological conditions of different seasons of the year is very significant. Periodicity in the life of animals and plants is the result of their adaptation to the annual change in meteorological conditions. It manifests itself in the development of a certain annual rhythm in their life, consistent with the meteorological rhythm. The need for low temperatures in the autumn period and for warmth during the growing season means that for plants of temperate latitudes, not only the general level of heat is important, but also a certain distribution of it over time. So, if plants are given the same amount of heat, but differently distributed: one has warm summers and cold winters, and the other has a corresponding constant average temperature, then normal development will be only in the first case, although the total amount of heat in both cases is the same.
The need for plants of temperate latitudes to alternate cold and warm periods during the year is called seasonal thermoperiodism.
Often the decisive factor of seasonal periodicity is the increase in the length of the day. The length of the day varies throughout the year: the sun shines the longest on the summer solstice in June, the least on the winter solstice in December.
Many living organisms have special physiological mechanisms that react to the length of the day and, in accordance with this, change their mode of action. For example, while the day is 8 hours long, the Saturnian butterfly chrysalis sleeps peacefully, because it is still winter outside, but as the day gets longer, special nerve cells in the pupa's brain begin to secrete a special hormone that causes it to wake up.
Seasonal changes in the fur coat of some mammals are also determined by the relative length of day and night, little or no dependence on temperature. So, by gradually artificially reducing the daylight hours in the enclosure, the scientists imitated autumn, as it were, and ensured that weasels and ermines kept in captivity changed their brown summer outfit to white winter ahead of time.
It is generally accepted that there are four seasons (spring, summer, autumn, winter). Ecologists who study communities of the temperate zone usually distinguish six seasons, which differ in the set of species in communities: winter, early spring, late spring, early summer, late summer and autumn. Birds do not adhere to the generally accepted division of the year into four seasons: the composition of the bird community, which includes both permanent inhabitants of the area and birds spending winter or summer here, changes all the time, while the maximum number of birds reaches in spring and autumn during migrations. In the Arctic, in fact, there are two seasons: a nine-month winter and three summer months, when the sun does not go below the horizon, the soil thaws and life wakes up in the tundra. As you move from the pole to the equator, the change of seasons is less determined by temperature, and more and more by humidity. In temperate deserts, summer is the period when life stops and blooms in early spring and late autumn.
The change of seasons is associated not only with periods of abundance or lack of food, but also with the rhythm of reproduction. In domestic animals (cows, horses, sheep) and animals in the natural environment of the temperate zone, offspring usually appear in the spring and grow up in the most favorable period, when there is most plant food. Therefore, the thought may arise that in the spring all animals breed in general.
However, the reproduction of many small mammals (mice, voles, lemmings) is often not strictly seasonal. Depending on the quantity and abundance of food, reproduction can take place both in spring, and in summer, and in winter.
In nature, it is observed in addition to daily and seasonal rhythms .multi-annual periodicity biological phenomena. It is determined by changes in the weather, its regular change under the influence of solar activity and is expressed by the alternation of productive and lean years, years of abundance or small populations.
D. I. Malikov for 50 years of observations noted five large waves of changes in the number of livestock, or as many as there were solar cycles (Fig. 7.8). The same relationship is manifested in the cyclicity of changes in milk yields, the annual increase in meat, wool in sheep, as well as in other indicators of agricultural production.
The frequency of changes in the properties of the influenza virus is associated with solar activity.
According to the forecast, after a relatively quiet period in terms of influenza in the early 80s. 20th century since 2000, a sharp increase in the intensity of its distribution is expected.
There are 5-6- and 11-year, as well as 80-90-year or secular cycles of solar activity. This makes it possible to some extent to explain the coincidence of the periods of mass reproduction of animals and the growth of plants with periods of solar activity.
The biological clockCircadian and circadian rhythms underlie the body's ability to sense time. The mechanism responsible for this periodic activity - be it feeding or reproduction - has been called the "biological clock." The amazing accuracy of the biological clock that controls the life of many plants and animals is the object of research by scientists. different countries peace.
As can be seen from the given curves, the leaves of legumes fall off at night, and straighten out again during the day. The activity graph of rats consists of successively alternating rectangular pits (day - the rat sleeps) and a plateau (night - the rat is awake). Houseflies mostly hatch from pupae in the morning. This adaptation has such deep roots that even under conditions of constant illumination, temperature and humidity, the flies retain their characteristic periodicity of behavior.
Many animals - various types of birds, turtles, bees, etc. - navigate their journeys through the heavenly bodies. It seems that for this you need to have not only a good memory that allows you to remember the position of the Sun or other luminaries, but also something like a chronometer showing how long it took the Sun and stars to take a new place in the sky. Organisms with such an internal biological clock have another advantage - they are able to "foresee" the onset of regularly repeating events and prepare accordingly for the upcoming changes. Thus, the bees are helped by their internal clocks to fly to the flower they visited yesterday, exactly at the time when it blooms. The flower visited by the bee also has some kind of internal clock, some kind of internal clock that signals the time of blooming. Everyone knows about the existence of their own biological clock. Waking up for several days in a row from the alarm clock, you quickly get used to waking up before what he calls. Today there are different points of view on the nature of biological clocks, their principle of operation, but one thing is certain - they really exist and are widely distributed in wildlife. Certain internal rhythms are also inherent in man. chemical reactions in his body occur, as shown above, with a certain frequency. Even during sleep, the electrical activity of the human brain changes every 90 minutes.
The biological clock, according to a number of scientists, is another environmental factor that limits the activity of living beings. The free settlement of animals and plants is prevented not only by environmental barriers, they are tied to their habitat not only by competition and symbiotic relationships, the boundaries of their ranges are determined not only by adaptations, but their behavior is also controlled indirectly, through the internal biological clock, by the movement of distant celestial bodies.
Seasons These are seasons that differ in weather and temperature. They change with the annual cycle. Plants and animals adapt perfectly to these seasonal changes.
Seasons on Earth
It is never very cold or very hot in the tropics, there are only two seasons: one is wet and rainy, the other is dry. At the equator (on the imaginary midline) it is hot and humid throughout the year.
In temperate zones (outside the lines of the tropics) there is spring, summer, autumn and winter. Generally, the closer to the North or South Pole, the cooler the summer and the colder the winter.
Seasonal changes in plants
Green plants need sunlight and water to form nutrients and grow. They grow most in spring and summer or during the wet season. They tolerate winter or dry seasons differently. Many plants have a so-called rest period. Many plants store nutrients in thickened parts underground. Their aerial part dies, the plant rests until spring. Carrots, onions and potatoes are the type of nutrient storage plants that people use.
Such as oak and beech shed their leaves in autumn because there is not enough sunlight at that time to produce nutrients in the leaves. In winter, they rest, and in spring new leaves appear on them.
evergreen trees always covered with leaves that never fall. To learn more about evergreen and shedding trees.
Some evergreen trees, such as pine and spruce, have long, thin leaves called needles. Many of the evergreen trees grow far north, where summers are short and cool and winters are harsh. Keeping their foliage, they can start growing as soon as spring arrives.
Deserts are usually very dry, sometimes there is no rain at all, and sometimes there are very short rainy seasons. Seeds germinate and give new shoots only in the rainy season. Plants bloom and produce seeds very quickly. They store nutrients
Seasonal changes in animals
Some animals, such as reptiles, reduce their activity and go to sleep to survive the cold or dry season. When it gets warmer, they return to an active lifestyle. Other animals behave differently, they have their own ways of surviving in harsh periods.
Some animals, such as the dormouse, sleep through the winter. This phenomenon is called hibernation. All summer they eat, accumulating fat so that in winter they can sleep without eating.
Most mammals and birds hatch their young in the spring, when there is plenty of food everywhere, so that they have time to grow and get stronger for the winter.
Many animals and birds undertake long journeys each year, called migrations, to places where there is more food. For example, swallows build nests in Europe in the spring, and fly to Africa in the fall. In the spring, when it becomes very dry in Africa, they return.
Caribou (called reindeer in Europe and Asia) also migrate, spending their summers above the Arctic Circle. Huge herds eat grass and other small plants where the ice melts. In autumn they move south to the evergreen forest area and feed on plants such as moss and lichen under the snow.
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2.2.5. Seasonal (circanial) rhythms
Biological rhythms with a period equal to one year (circanial) are traditionally called seasonal rhythms. Despite the progress in the development of means of protection against sudden changes in environmental parameters, a person shows annual fluctuations in biochemical, physiological and psychophysiological processes. Seasonal biorhythms, covering, in essence, all functions, are reflected in the state of the organism as a whole, on the health and working capacity of a person.
Fundamentals of circannual rhythms. The complex of external and internal causes that cause circannual rhythms can be conditionally divided into three groups according to the mechanism of action.
1. Adaptive changes in the functional state of the body, aimed at compensating for annual fluctuations in the main environmental parameters and, above all, temperature, as well as the qualitative and quantitative composition of food.
2. Response to environmental signal factors - daylight hours, geomagnetic field strength, some chemical components of food. Environmental factors that play the role of seasonal "time sensors" are capable of causing significant morphological and functional changes in the body.
3. Endogenous mechanisms of seasonal biorhythms. The action of these mechanisms is adaptive in nature, providing a full-fledged adaptation of the body to seasonal changes in environmental parameters.
The conjugation of seasonal changes in illumination, environmental temperature conditions, and food composition makes it difficult to separate their role in the formation of circannual rhythms of the physiological systems of the body. It should be noted the significant importance of social factors in the formation of seasonal biorhythms in humans.
Seasonal fluctuations in character behavioral responses person.
In the process of nutrition, the total calorie content of food increases in the autumn-winter period. Moreover, in summer the consumption of carbohydrates increases, and in winter - fats. The latter leads to an increase in total lipids, triglycerides and free fats in the blood. The vitamin composition of food has a significant impact on the change in the functional state of the body in different seasons.
The intensity of energy metabolism is greater in the winter-spring period compared to summer, and heat transfer from the skin surface has the opposite direction. Depending on the season of the year, there is a significant difference in the body's thermoregulatory response to heat and cold stress. Resistance to thermal loads increases in summer and decreases in winter. A clear seasonal periodicity is characteristic of the intensity of growth processes. The maximum increase in body weight in children is observed in the summer months.
There are numerous data on seasonal fluctuations in the neuroendocrine system. Thus, the activity of the parasympathetic division of the autonomic nervous system is maximum in the spring months. At the same time, the concentration of tropic hormones of the pituitary gland in the blood increases. Thyroid activity increases during the winter months. Glucocorticoid function of the adrenal glands is minimal in the summer, and the activity of the sympathoadrenal system has a peak in the winter months.
The seasonal dynamics of the reproductive function is associated with photoperiodism (fluctuations in the duration of daylight and darkness). With the lengthening of the night, there is an increase in the production of melatonin by the pineal gland, which, in turn, leads to inhibition of the gonadotropic function of the hypothalamic-pituitary system.
According to numerous observations, the functional activity of the cardiovascular system is higher in the spring months. This is manifested in higher rates of heart rate, blood pressure, and contractile function of the myocardium. Comprehensive studies of blood circulation, respiration and blood show that seasonal fluctuations are characteristic of the oxygen transport system of the body and are apparently determined by fluctuations in the intensity of energy metabolism.
Seasonal fluctuations in the intensity of energy metabolism and the activity of the neuroendocrine system cause regular fluctuations in the activity of various physiological systems of the body. Observations of the state and behavior of a person reveal seasonal changes in performance. So, the level of physical performance is minimal in winter and maximal in late summer - early autumn.
2.2.6. Influence of heliogeophysical factors on human biorhythms
The term "heliogeophysical factors" is understood as a complex of physical factors that affect the human body and are associated with solar activity, the rotation of the Earth, fluctuations in geomagnetic fields, features of the structure and state of the atmosphere. Heliogeophysical factors determine the weather and climate conditions. Their fluctuations, both individually and in combination, can have an ambiguous effect on human biorhythms.
Solar activity factors are important element when synchronizing the rhythm of biological systems in the ranges of meso- and macrorhythms (Table 2.6). Ultradian rhythms of sleep phases are modulated by solar activity. The frequencies of some short-period biorhythms correlate with the frequencies of regulatory micropulsations of the geomagnetic field and acoustic oscillations that occur during magnetic storms. The leading component of these oscillations is a frequency of about 8 Hz. For example, tremor rhythm, EEG alpha wave rhythm, ECG rhythm correlate with electromagnetic pulsation frequencies. The rhythm of mitochondria, glycolysis, and protein synthesis correlates with acoustic phenomena (infrasound). There is evidence of the existence of biorhythms with a range of solar pulsation fluctuations (2 h 40 min). Near-weekly or multiple changes in human physiological parameters are better known. It turned out that this rhythm is associated with the passage of the Earth near the boundaries of the sectors of the interplanetary magnetic field.
The influence of weather factors, such as air temperature, humidity, atmospheric pressure, etc., on biorhythms was studied. It turned out that physiological parameters are associated with weather conditions more often by simple linear relationships. So, with an increase in any weather factor (for example, air temperature), there is an increase in the values of a person's physiological parameters (for example, blood pressure, respiratory rate, muscle strength of the hands) or their decrease.
In some cases (dependence of body temperature on external temperature, dependence of body temperature and respiratory rate on atmospheric pressure, etc.), weather factors cause an alternating reaction of strengthening and weakening, that is, they maintain an oscillatory state of functions.
Table 2.6. Periods and cycles of heliophysical factors (after: B. M. Vladimirsky, 1980)
The results of the studies made it possible to distinguish two types of influences of geomagnetic and weather factors on changes in physiological parameters.
The influence of solar activity (chromospheric flares) and weather factors (which themselves depend on solar activity) most often manifests itself in the form of simple linear relationships. The effects of a constant magnetic field and random magnetic disturbances are non-linear and create a constant and "rhythmic" background, causing (depending on its own parameters and the functional state of the living system) the reaction of either strengthening or weakening the function.
...Thus, the Earth's magnetic fields seem to maintain the existence of oscillatory circuits, while solar activity and weather factors modulate biological rhythms.
For an organism with an already formed biorhythmic system external influences play the role of "time sensors", maintaining the overall level of fluctuations (as can be seen under the action of magnetic field parameters and some weather factors), adjusting the period (change in rhythm in different seasons due to changes in illumination and other factors) and amplitude of fluctuations (influence atmospheric pressure, humidity, temperature, solar flares).
2.2.7. Adaptive restructuring of biological rhythms
...With a sharp change in the rhythms of the external environment (geophysical or social), there is a mismatch of endogenously determined fluctuations in the physiological functions of a person. Such a violation of conjugation of periodic oscillations of functionally interconnected systems of the body is called desynchronosis.
Symptoms of desynchronosis are reduced to sleep disorders, decreased appetite, mood, mental and physical performance, and various neurotic disorders. In some cases, organic diseases are noted (gastritis, peptic ulcer, etc.).
The state when the system of circadian rhythms of the body does not correspond to temporary environmental conditions is called external desynchronosis. Under the influence of new "time sensors", the restructuring of the previously established system of circadian rhythms of the body begins. At the same time, physiological functions are rebuilt at different speeds, the phase structure of the rhythms of physiological functions is disturbed - internal desynchronization. It accompanies the entire period of adaptation of the body to new temporary conditions and sometimes lasts for several months.
Among the factors leading to the adaptive restructuring of biological rhythms, there are:
- change of time zones (travels over considerable distances in the latitudinal direction, transmeridian flights);
– stable phase mismatch with local time sensors of the “sleep-wake” rhythm (work in the evening and night shift);
- partial or complete exclusion of geographic time sensors (conditions of the Arctic, Antarctic, etc.);
- exposure to various stressors, among which may be pathogenic microbes, pain and physical stimuli, mental or increased muscle tension, etc.
Increasingly, there is information about the mismatch of the biological rhythms of a person with the rhythms of his social activity that make up the way of life - the mode of work and rest, etc.
The restructuring of biorhythms also occurs under the influence of unfavorable conditions that are not primarily associated with the transformation of rhythms and lead to the development of desynchronosis only secondarily. Such an effect has, for example, fatigue. Therefore, in some cases, specific synchronosis occurs as a result of unusual or excessive demands on the circadian system (for example, time shifts), in others, nonspecific desynchronosis occurs as a result of adverse social and biological factors affecting the body.
The following types of desynchronosis are distinguished: acute and chronic, overt and hidden, partial and total, as well as asynchronosis.
Acute desynchronosis appears episodically in case of emergency mismatch of time sensors and daily rhythms of the body (for example, a reaction to a quick single movement in the latitudinal direction), while chronic - with repeated mismatches of time sensors and daily rhythms of the body (for example, a reaction to repeated movements in the transmeridional direction or when adapting to night shift work).
Explicit desynchronosis manifests itself in subjective reactions to the mismatch of time sensors with the daily cycles of the body (complaints of poor sleep, decreased appetite, irritability, drowsiness in daytime etc.). Objectively, there is a decrease in working capacity, inconsistency in the phase of physiological functions with time sensors. Explicit desynchronosis disappears over time: the state of health improves, performance is restored, and synchronization in the phase of the rhythms of individual functions and time sensors partially occurs. However, from partial to complete restructuring of the circadian system, a much longer period of time (up to several months) is required, during which signs of the so-called latent desynchronosis are determined.
Partial, total desynchronosis and asynchronosis mainly reflect a different degree of desynchronization of functions in the body, which is due to the degree of divergence of the phases of their rhythms. In the first case, the mismatch of circadian rhythms of functions, desynchronization is observed only in some links, in the second case, in most links of the circadian system. With the most severe degree - asynchronosis - individual links of the circadian system turn out to be completely disconnected, desynchronized, which is actually incompatible with life.
A large load on the chronophysiological system of the body is created by flights with a change in time zones. The duration and nature of the restructuring of physiological functions in this case depend on many factors, of which the leading one is the magnitude of the hourly shift. A distinct restructuring of circadian rhythms begins after a flight through 4 or more time zones. The next factor is the direction of the move. Surveys of different contingents of people during transmeridional flights both to the west and to the east showed that movements in different directions have their own specifics. Other things being equal, the climatic contrast of the points of flight plays an equally important role.
It is interesting to note that during a transmeridional flight, functional shifts in the body (subjective discomfort, emotional, hemodynamic reactions, etc.) are more pronounced than during a slow crossing of belt zones (by train, on ships), when a person "fits" into a displaced spatial temporary structure of the environment gradually. Nevertheless, moving by train is accompanied by its own subjective discomfort, specific for different directions.
The rate of restructuring of the circadian rhythm also depends on the age and gender of the person, his individual characteristics and professional affiliation. Thus, the normalization of the circadian rhythm in women occurs faster than in men. Anatomical and physiological immaturity of the child's body and the mobility of functional manifestations in adolescents are lung cause occurrence of desynchronosis. At the same time, the high plasticity of the CNS in adolescents ensures their faster and less difficult adaptation to transmeridional movement. The least pronounced and faster are all reactions of the body in well-trained athletes.
Stages of the adaptation process. Studies have shown that the process of adaptation of the body when changing time zones occurs in stages. The stage of desynchronization, the stage of unstable synchronization and the stage of stable synchronization are distinguished, when both the phases of the circadian rhythms themselves and the relationship between them are normalized. It should be noted that the process of rearrangement of circadian rhythms of various physiological systems proceeds relatively independently and at different rates. The sleep and wakefulness regimen, simple psychomotor reactions are most quickly rebuilt. Restoration of the circadian rhythm of complex psychophysiological functions occurs within 3–4 days. For the restructuring of the rhythms of the cardiovascular, respiratory, digestive, excretory systems, a longer period is needed. The longest time (12–14 days) is required for restructuring the circadian rhythm of thermoregulation, hormonal activity, and basal metabolism in accordance with the new standard time.
Strong synchronizers of daily rhythms of biochemical and physiological processes are physical activity, sleep and meal times. The mode of sleep and wakefulness plays the main role in accelerating the normalization of the circadian rhythm during many hours of latitudinal movements.
When compiling a special diet and diet, consider the following:
1) the action of food as a time sensor;
2) chronobiological action of theophylline in tea and caffeine in coffee;
3) the property of food rich in proteins to promote the synthesis of catecholamines, and food rich in carbohydrates to promote the synthesis of serotonin.
It has been shown that relatively high blood levels of adrenaline and norepinephrine are required during wakefulness, and serotonin during sleep.
Some researchers propose to establish a mode of life corresponding to the new standard time a few days before the flight. However, this issue remains debatable.
For short business trips, it is recommended not to change the usual daily routine and hours of sleep, and if necessary, take a sleeping pill or tonic. A combination of these means is also possible. Circadian rhythms after a flight recover much faster under special regimes of alternating light and dark.
2.3. General issues of adaptation of the human body to various climatic and geographical regions
2.3.1. Human adaptation to the conditions of the Arctic and Antarctic
environmental factors. In the conditions of the Arctic and Antarctic, a person is affected by a complex of factors, such as low temperature, fluctuations in geomagnetic and electric fields, atmospheric pressure, etc. The degree of their impact may vary depending on the climatic and geographical features of the area. However, these factors are not equivalent for the human body. Historically, the primary focus was on studying the effects of cold on the human body. Only in the second half of the last century, researchers paid attention to the effects of other factors.
...At present, it is believed that phenomena that have a particularly important impact on humans space nature: cosmic rays and changes in solar activity. The features of the structure of the geomagnetic sphere are such that in the region of "cold" latitudes, the Earth is most poorly protected from cosmic radiation. The radiation regime, which is the leading one in the complex of climatic elements affecting a person, is subject to significant fluctuations.
The constant change of physical environmental factors accompanying the alternation of the polar night and polar day(first of all, the nature of the light regime), determines the rhythmic features of the body's reactions. At the same time, all physiological systems of the body are involved in the adaptive process.
According to V. P. Kaznacheeva, biophysical factors are characterized by the impact of geomagnetic and cosmic disturbances on biochemical and biophysical processes in the body, followed by a change in the structure of cell membranes. The shifts they cause at the molecular level stimulate further metabolic reactions at the cellular, tissue and organism levels.
Phases of human adaptation to the conditions of the Arctic and Antarctic.
The duration of each phase is determined by objective and subjective factors, such as climatic, geographical and social conditions, individual characteristics organism, etc.
The initial period of adaptation lasts up to six months. It is characterized by destabilization of physiological functions.
The second phase takes 2-3 years. At this time, there is some normalization of functions, which is noted both at rest and during exercise.
In the third phase, which lasts 10–15 years, the state of the body stabilizes. However, in order to maintain a new level of vitality, it is necessary constant pressure regulatory mechanisms, which can lead to the depletion of the reserve capacity of the body.
Forms of reactions of an organism to a complex of factors of high latitudes.
There are nonspecific and specific reactions.
At the core non-specific adaptive reactions are nervous and humoral mechanisms. The most common non-specific reaction is the excitation of the central nervous system, which is accompanied by an increase in metabolism, the activity of the endocrine glands and the functions of organs and systems of the body.
At the core specific reactions (for example, the syndrome of polar and antarctic stress) is a complex of functional changes in the psychosomatic and vegetative spheres at the systemic and tissue levels. Among the factors causing this state of the body, the leading ones are psychological, social and biophysical.
Many authors note the seasonal nature of changes in the reactions of the body in the conditions of the Arctic and Antarctic. So, during the polar night, the visiting population is dominated by inhibitory processes in the central nervous system. The capacity of analyzer systems decreases, the reliability of the performance of the integrative functions of the brain decreases. Objective changes in higher nervous activity, as a rule, are accompanied by complaints of general weakness, weakness, drowsiness, fatigue, headaches, and transient pains in the region of the heart. Various kinds of neurasthenic disorders, mental depression, and unbalanced behavior are growing. The oppression of the mental sphere is accompanied by a violation of the autoregulatory functions of the brain. Significant inhibition of vascular and respiratory reflexes was noted. During the polar night, migrants most clearly manifest polar shortness of breath, up to a violation of the normal rhythm of breathing. Decreased basal metabolic rate. Seasonal variability is inherent in the mechanisms of physical and chemical thermoregulation.
It is known that the greatest number of diseases occurs in the middle of the polar night. This is due to a decrease in the body's immune reactivity. The polar explorers found a decrease in the number of erythrocytes and hemoglobin, which is explained by the long absence of sunlight in the winter.
The polar day, with its excessive ultraviolet radiation background, in turn, can have sub-extreme effects on the body. In this case, the stereotyped reactions developed during the polar night are broken. First, the polar day produces an exciting effect, but then the phenomena of overexcitation and overwork develop. This is facilitated by a sharp increase in the intensity of natural light, which leads to an increase in the tone of the visual cortex and, through the optic-vegetative tract, the underlying subcortical centers. Excitation of the visual cortex radiates to other areas.
The period of the polar day is characterized by the predominance of the tone of the sympathetic division of the autonomic nervous system, an increase in the level of adrenaline and corticosteroids in the blood. At this time, the electrical conductivity and temperature of the skin increases, the heart rate increases, blood pressure, respiratory rate, and oxygen utilization increase. However, prolonged and continuous light stimulation leads to the transition of excitation into a state of protective inhibition.
Information about the trend of shifts occurring in the physiological systems of the body in the conditions of the Arctic and Antarctic is very contradictory. There are many reasons for this. This includes the difference between natural and social conditions those places where studies were carried out (cities and towns, research stations, ships), heterogeneity of the composition of the examined by age, gender, professional affiliation, discrepancies in the methods and timing of surveys, etc.
The degree of involvement of individual body systems in the process of adaptation to the conditions of the Arctic and Antarctic is determined by the modality of extreme factors and the individual reactivity of the body. For example, psycho-emotional and social factors predominantly modulate the functional state of the brain, geophysical factors - tissue metabolism of the stroma and parenchyma; cold mechanisms of physical and chemical thermoregulation.
Nervous system
The reactions of the body aimed at maintaining homeostasis in extreme and subextreme conditions of existence in the Arctic and Antarctic are primarily regulated by the central nervous system. The action of a specific complex of stimuli causes a functional restructuring of the cerebral cortex and subcortical vegetative centers. Humoral components of regulation are involved in the reactions of the body through the subcortical centers and the hypothalamus: hormones, metabolites, adrenergic and cholinergic mediators, vitamins, etc. All this leads to a restructuring of the activity of the structural elements of the body at various levels (organismic, systemic, organ, tissue, molecular) and in a certain sequence depending on the stages of adaptation.
In people who first find themselves in the conditions of the Arctic and Antarctic, a set of symptoms occurs, which is called the syndrome of psycho-emotional stress. Its appearance indicates the strain of adaptive mechanisms. The main clinical manifestation psycho-emotional tension syndrome is anxiety of varying severity, from a state of psychological discomfort to a neurotic level of anxiety. Anxiety can be combined with some improvement in mood, euphoria, and increased psychomotor activity. Motor restlessness in the structure of the syndrome of psycho-emotional stress has the character of purposeful activity. It is expressed in an increased desire for work, various forms of social activity. This softens the feeling of psychological discomfort, calms for a while.
The process of adaptation to the conditions of the Arctic and Antarctic is accompanied by a change in psychophysiological indicators, such as the strength and mobility of nervous processes. Attention, differentiated inhibition, associative functions of memorization do not change. Psychoemotional stress syndrome is characterized by a number of physiological abnormalities. In persons with severe emotional stress, there is a clear tendency to increase blood pressure. The conditioned and unconditioned vascular and respiratory reflexes change significantly.
In some people, when the processes of adaptation to the conditions of the Arctic and Antarctic are disturbed, pathological changes often occur in the body. The terms used to denote such a reaction are "disadaptive neurosis" or "disadaptation syndrome".
Efficiency psychological adaptation to the conditions of the Arctic and Antarctic is largely determined by motivation. It is greatly facilitated in people with a social disposition, interested in material and especially moral incentives.
Endocrine system
The cold climate of high latitudes is one of the most unfavorable factors affecting people in these areas. A persistent increase in the tone of the sympathoadrenal system, high activity of the thyroid gland are among the most characteristic shifts in endocrine regulation in people adapting to polar conditions. The important role of catecholamines and thyroid hormones in the regulation of the body's caloric balance has been shown.
The temperature adaptation process is divided into several phases. Initially, an increase in resistance to cold, as with any stressful effect, is achieved by nonspecific mobilization of the endocrine system. In the future, the role of specific components increases. Among other mechanisms of specific adaptation to cold, an increase in the calorigenic effect of norepinephrine occupies a large place.
In the conditions of the Arctic for a person, a condition that is not indifferent is a kind of light periodicity. A strict relationship was shown between the trophic nervous and hormonal mechanisms in the body and the nature of photoperiodism. Rhythmic fluctuations in the secretion of tropic hormones of the pituitary gland, occurring under the influence of the change of light and darkness, are the cause of the periodicity of physiological processes. In humans, the light period corresponds to the predominance of the tone of the sympathetic part of the autonomic nervous system and an increased level of adrenaline and corticosteroids, the dark period corresponds to the predominance of the parasympathetic tone and an increased level of melanotropic hormone.
...Studies conducted using correlation analysis have shown that a large number climatic and geophysical parameters characterizing the conditions of the Arctic and Antarctic (atmospheric pressure, temperature, wind speed, humidity, etc.), the change in the Earth's magnetic field was especially significant for the mobilization of endocrine functions. High ionization of the atmosphere of the Arctic, proximity magnetic pole make this region the most unfavorable in terms of changes in the intensity and frequency of magnetic field oscillations. A close relationship between the action of these factors and the level of excretion of neutral ketosteroids and adrenaline was revealed.
In addition to natural factors, the dynamics of endocrine changes is also influenced by psycho-emotional state person. The degree of change in endocrine homeostasis depends on the time spent in the North.
Blood system
Information about the state of red blood in the visiting population of the Arctic and Antarctic is extremely contradictory. In Antarctica, in high altitude conditions, polar explorers, as a rule, have an activation of erythropoiesis caused by an increase in the level of erythropoietins in the blood under the influence of high-altitude hypoxia. In the newcomers to the Arctic, under the influence of such factors as cold, many months of absence of sunlight, relative physical inactivity, lack of vitamins, there is a decrease in the number of red blood cells and hemoglobin. They are characterized by significant leukopenia, a reduced number of stab and segmented neutrophils, monocytes. The content of eosinophils is increased, sometimes eosinopenia occurs.
Blood clotting depends on the timing of adaptation. Initially, the clotting time and recalcification of blood increases, and plasma tolerance to heparin decreases. Increases the number of platelets and their activity. In the future, the process of blood coagulation is significantly shortened. With a decrease in plasma tolerance to heparin, its fibrinolytic activity is increased, and the time of thrombus formation is accelerated. After several years in the North, these figures are normalized.
In the process of adaptation to arctic conditions in people, the overall immune reactivity decreases, and the phagocytic activity of the blood decreases. This is due to the suppression of the formation of antibodies, shifts in the leukocyte formula. As a result, people get sick more often.
The cardiovascular system
The adaptation of the cardiovascular system of people to the complex of natural factors characteristic of high latitudes has a phase character. A short stay in the conditions of the Arctic (2–2.5 years) leads to the mobilization of adaptive reactions of the circulatory system, which is accompanied by increased heart rate, increased blood pressure, and peripheral vascular resistance.
Further stay in the North (3–6 years) is characterized by such changes in the cardiovascular system as a gradual decrease in heart rate, a moderate decrease in systolic and minute blood volumes.
With long-term residence in the Arctic (10 years or more), a further restructuring of the functioning of the circulatory system occurs. It is characterized by a tendency to bradycardia, a pronounced decrease in systolic and minute blood volumes, a compensatory increase in blood pressure, and peripheral vascular resistance. It is believed that this is caused by the depletion of regulatory mechanisms, increased parasympathetic control, followed by the development of negative chronotropic and inotropic effects, the development of desynchronosis phenomena in the blood pressure period. At the same time, the incidence of hypertension, myocardial infarction is increasing.
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