Adaptations are various adaptations to the environment developed in organisms during the process of evolution. .

There are three main ways that organisms adapt to environmental conditions: the active path, the passive path, and the avoidance of adverse effects.

The active path is strengthening resistance, developing regulatory processes that allow all vital functions of the body to be carried out, despite factor deviations from the optimum. For example, maintaining a constant body temperature in warm-blooded animals (birds and mammals), optimal for the occurrence of biochemical processes in cells.

The passive way is the subordination of the vital functions of the body to changes in environmental factors. For example, the transition under unfavorable environmental conditions to a state of anabiosis (hidden life), when the metabolism in the body almost completely stops (winter dormancy of plants, preservation of seeds and spores in the soil, torpor of insects, hibernation of vertebrates).

Avoidance of adverse effects - the body develops such life cycles and behavior that allow it to avoid adverse effects. For example, seasonal migrations of animals.

Adaptations can be divided into three main types: morphological, physiological and ethological.

Morphological adaptations are changes in the structure of the body (for example, the modification of a leaf into a spine in cacti to reduce water loss, the bright color of flowers to attract pollinators). Morphological adaptations in plants and animals lead to the formation of certain life forms.

Physiological adaptations are changes in the physiology of the body (for example, the ability of a camel to provide the body with moisture by oxidizing fat reserves, the presence of cellulose-degrading enzymes in cellulose-degrading bacteria).

Ethological (behavioural) adaptations – changes in behavior (for example, seasonal migrations of mammals and birds, hibernation in winter, mating displays in birds and mammals during the breeding season).

15. Aquatic life environment and its characteristics. Classification of hydrobionts

Hydrobionts - (from the Greek hydor - water and bios - life) organisms living in the aquatic environment.

Diversity of aquatic organisms

Pelagic organisms (plants or animals that live in or on the surface of water)

Neuston is a collection of microorganisms living near the surface film of water at the boundary of the water and air environments.

Plaiston - plant or animal organisms living on the surface of water, or semi-submerged in water.

Rheophiles are animals that have adapted to living in flowing waters.

Nekton is a collection of aquatic actively swimming organisms that can withstand the force of the current.

Plankton are heterogeneous, mostly small organisms that drift freely in the water column and are unable to resist the current.

Benthos (a set of organisms living on the ground and in the soil of the bottom of reservoirs)

The hydrosphere as an aquatic living environment occupies about 71% of the area and 1/800 of the volume of the globe. The main amount of water, more than 94%, is concentrated in the seas and oceans. In fresh waters of rivers and lakes, the amount of water does not exceed 0.016% of the total volume of fresh water.

In the ocean with its constituent seas, two ecological regions are primarily distinguished: the water column - pelagic and the bottom - benthic. Depending on the depth, the benthal is divided into a sublittoral zone - an area of ​​smooth decline of land to a depth of 200 m, a bathyal zone - an area of ​​a steep slope and an abyssal zone - the oceanic bed with an average depth of 3-6 km. The deeper benthic regions corresponding to the depressions of the ocean floor (6-10 km) are called ultra-abyssal. The edge of the coast that is flooded during high tides is called the littoral zone. The part of the coast above the tide level, moistened by the spray of the surf, is called the superlittoral.

The open waters of the World Ocean are also divided into zones vertically corresponding to the benthic zones: epipeligal, bathypeligal, abyssopeligal.

The aquatic environment is home to approximately 150,000 animal species, or about 7% of the total, and 10,000 plant species (8%).

The share of rivers, lakes and swamps, as noted earlier, is insignificant compared to seas and oceans. However, they create the supply of fresh water necessary for plants, animals and humans.

A characteristic feature of the aquatic environment is its mobility, especially in flowing, fast-flowing streams and rivers. The seas and oceans experience ebbs and flows, powerful currents, and storms. In lakes, water moves under the influence of temperature and wind.

16. Ground-air environment of life, its characteristics and forms of adaptation to it

Life on land required adaptations that turned out to be possible only in highly organized living organisms. The terrestrial-air environment is more difficult for life; it is characterized by a high oxygen content, low amount of water vapor, low density, etc. This greatly changed the conditions of breathing, water exchange and movement of living beings.

Low air density determines its low lifting force and insignificant support. Organisms of the air environment must have their own support system that supports the body: plants - various mechanical tissues, animals - a solid or hydrostatic skeleton. In addition, all inhabitants of the air are closely connected with the surface of the earth, which serves them for attachment and support.

Low air density provides low resistance to movement. Therefore, many land animals acquired the ability to fly. 75% of all terrestrial animals, mainly insects and birds, have adapted to active flight.

Thanks to the mobility of air and the vertical and horizontal flows of air masses existing in the lower layers of the atmosphere, passive flight of organisms is possible. In this regard, many species have developed anemochory - dispersal with the help of air currents. Anemochory is characteristic of spores, seeds and fruits of plants, protozoan cysts, small insects, spiders, etc. Organisms passively transported by air currents are collectively called aeroplankton.

Terrestrial organisms exist in conditions of relatively low pressure due to low air density. Normally it is 760 mmHg. As altitude increases, pressure decreases. Low pressure may limit the distribution of species in the mountains. For vertebrates, the upper limit of life is about 60 mm. A decrease in pressure entails a decrease in oxygen supply and dehydration of animals due to an increase in respiration rate. Higher plants have approximately the same limits of advancement in the mountains. Arthropods, which can be found on glaciers above the vegetation line, are somewhat more hardy.

Gas composition of air. In addition to the physical properties of the air, its chemical properties are very important for the existence of terrestrial organisms. The gas composition of air in the surface layer of the atmosphere is quite uniform in terms of the content of the main components (nitrogen - 78.1%, oxygen - 21.0%, argon - 0.9%, carbon dioxide - 0.003% by volume).

The high oxygen content contributed to an increase in metabolism in terrestrial organisms compared to primary aquatic organisms. It was in a terrestrial environment, on the basis of the high efficiency of oxidative processes in the body, that animal homeothermy arose. Oxygen, due to its constant high content in the air, is not a limiting factor for life in the terrestrial environment.

The carbon dioxide content can vary in certain areas of the surface layer of air within fairly significant limits. Increased air saturation with CO? occurs in areas of volcanic activity, near thermal springs and other underground outlets of this gas. In high concentrations, carbon dioxide is toxic. In nature, such concentrations are rare. Low CO2 content inhibits the process of photosynthesis. In closed soil conditions, you can increase the rate of photosynthesis by increasing the concentration of carbon dioxide. This is used in the practice of greenhouse and greenhouse farming.

Air nitrogen is an inert gas for most inhabitants of the terrestrial environment, but certain microorganisms (nodule bacteria, nitrogen bacteria, blue-green algae, etc.) have the ability to bind it and involve it in the biological cycle of substances.

Moisture deficiency is one of the essential features of the land-air environment of life. The entire evolution of terrestrial organisms was under the sign of adaptation to obtaining and preserving moisture. Humidity regimes on land are very diverse - from complete and constant saturation of the air with water vapor in some areas of the tropics to their almost complete absence in the dry air of deserts. There is also significant daily and seasonal variability in the content of water vapor in the atmosphere. The water supply of terrestrial organisms also depends on the precipitation regime, the presence of reservoirs, soil moisture reserves, the proximity of pound waters, etc.

This led to the development of adaptation to various water supply regimes in terrestrial organisms.

Temperature regime. Another distinctive feature of the air-ground environment is significant temperature fluctuations. In most land areas, daily and annual temperature ranges are tens of degrees. Resistance to temperature changes in the environment among terrestrial inhabitants is very different, depending on the specific habitat in which their life takes place. However, in general, terrestrial organisms are much more eurythermic compared to aquatic organisms.

Living conditions in the ground-air environment are further complicated by the existence of weather changes. Weather - continuously changing conditions of the atmosphere at the surface, up to an altitude of approximately 20 km (the boundary of the troposphere). Weather variability is manifested in a constant variation in the combination of environmental factors such as temperature, air humidity, cloudiness, precipitation, wind strength and direction, etc. The long-term weather regime characterizes the climate of the area. The concept of “Climate” includes not only the average values ​​of meteorological phenomena, but also their annual and daily cycle, deviation from it and their frequency. The climate is determined by the geographical conditions of the area. The main climatic factors - temperature and humidity - are measured by the amount of precipitation and the saturation of air with water vapor.

For most terrestrial organisms, especially small ones, the climate of the area is not so important as the conditions of their immediate habitat. Very often, local environmental elements (relief, exposure, vegetation, etc.) change the regime of temperatures, humidity, light, air movement in a particular area in such a way that it differs significantly from the climatic conditions of the area. Such climate modifications that develop in the surface layer of air are called microclimate. In each zone the microclimate is very diverse. Microclimates of very small areas can be identified.

The light regime of the ground-air environment also has some peculiarities. The intensity and amount of light here are greatest and practically do not limit the life of green plants, as in water or soil. On land, extremely light-loving species may exist. For the vast majority of terrestrial animals with daytime and even nighttime activity, vision is one of the main methods of orientation. In terrestrial animals, vision is important for searching for prey; many species even have color vision. In this regard, victims develop such adaptive features as a defensive reaction, camouflage and warning coloration, mimicry, etc. In aquatic inhabitants, such adaptations are much less developed. The appearance of brightly colored flowers of higher plants is also associated with the characteristics of the pollinator apparatus and, ultimately, with the light regime of the environment.

The terrain and soil properties are also the living conditions for terrestrial organisms and, first of all, plants. The properties of the earth's surface that have an ecological impact on its inhabitants are united by “edaphic environmental factors” (from the Greek “edaphos” - “soil”).

In relation to different soil properties, a number of ecological groups of plants can be distinguished. Thus, according to the reaction to soil acidity, they are distinguished:

acidophilic species - grow on acidic soils with a pH of at least 6.7 (plants of sphagnum bogs);

neutrophilic - tend to grow on soils with a pH of 6.7-7.0 (most cultivated plants);

basophilaceae - grow at a pH of more than 7.0 (Echinops, wood anemone);

indifferent - can grow on soils with different pH values ​​(lily of the valley).

Plants also differ in relation to soil moisture. Certain species are confined to different substrates, for example, petrophytes grow on rocky soils, pasmophytes populate loose sand.

The terrain and the nature of the soil influence the specific movement of animals: for example, ungulates, ostriches, bustards living in open spaces, hard ground, to enhance repulsion when running. In lizards that live in shifting sands, the toes are fringed with a fringe of horny scales that increase support. For terrestrial inhabitants that dig holes, dense soil is unfavorable. The nature of the soil in certain cases affects the distribution of terrestrial animals that dig holes or burrow into the soil, or lay eggs in the soil, etc.

17. Soil as a living environment. Classification of soil animals, form of adaptation

Soil is the surface layer of land, consisting of a mixture of mineral substances obtained from the decay of rocks, and organic substances resulting from the decomposition of plant and animal remains by microorganisms. The surface layers of the soil are inhabited by various organisms that destroy the remains of dead organisms (fungi, bacteria, worms, small arthropods, etc.). The active activity of these organisms contributes to the formation of a fertile soil layer suitable for the existence of many living beings. The soil is characterized by high density, slight temperature fluctuations, moderate humidity, insufficient oxygen content and high concentration of carbon dioxide. Its porous structure allows the penetration of gases and water, which creates favorable conditions for soil organisms such as algae, fungi, protozoa, bacteria, arthropods, mollusks and other invertebrates.

Adaptations of organisms to the environment are called adaptation. Adaptations are any changes in the structure and function of organisms that increase their chances of survival.

There are two types of adaptation: genotypic and phenotypic.

According to the definition of the Great Medical Encyclopedia (BME): “... genotypic adaptation occurs due to the selection of cells with a certain genotype, which determines endurance.” This definition is not perfect, since it does not reflect what type of load endurance refers to, since in most cases, while acquiring some advantages, living organisms lose others. If, for example, a plant tolerates a hot, dry climate well, then most likely it will not tolerate a cold and humid climate well.

As for phenotypic adaptation, there is currently no strict definition of this term.

According to the BME definition, “... phenotypic adaptation occurs as a protective reaction to the action of a damaging factor.”

According to the definition of F.Z. Meyerson “Phenotypic adaptation is a process that develops during an individual’s life, as a result of which the organism acquires previously absent resistance to a certain environmental factor and thus gains the opportunity to live in conditions previously incompatible with life...”

The ability to adapt is one of the main properties of life in general, since it provides the very possibility of its existence, the ability of organisms to survive and reproduce. Adaptations manifest themselves at different levels: from the biochemistry of cells and the behavior of individual organisms to the structure and functioning of communities and ecological systems. Adaptations arise and develop during the evolution of species.

Adaptation Mechanisms

Basic mechanisms of adaptation at the organism level:

1) biochemical - manifest themselves in intracellular processes, such as, for example, a change in the work of enzymes or a change in their quantity;

2) physiological - for example, increased sweating with increasing temperature in a number of species;

3) morpho-anatomical - features of the structure and shape of the body associated with lifestyle;

4) behavioral - for example, animals searching for favorable habitats, creating burrows, nests, etc.;

5) ontogenetic - acceleration or deceleration of individual development, promoting survival when conditions change.

Let's look at these mechanisms in more detail.

Biochemical mechanisms. Animals living in the coastal (littoral) zone of the sea are well adapted to the effects of adverse environmental factors and, thanks to a set of adaptations, are able to survive in conditions of oxygen deficiency. In particular: they have developed additional mechanisms for consuming oxygen from the environment; they are able to maintain the body’s internal energy resources by switching to anaerobic metabolic pathways; they reduce their overall metabolic rate in response to low oxygen concentrations in seawater. Moreover, the third method is considered the main and one of the most important mechanisms of adaptation to a lack of oxygen for many species of marine mollusks. During periodic drying events resulting from tidal cycles, intertidal bivalves are exposed to short-term anoxia and switch their metabolism to an anaerobic pathway. As a result, they are considered typical facultative anaerobic organisms. It is known that the metabolic rate in marine Bivalvia during anoxia decreases by more than 18 times. By reducing the metabolic rate, hypoxia/anoxia significantly affects the growth and many other physiological characteristics of mollusks.

Over the course of evolution, marine bivalves have developed a set of biochemical adaptations that allow them to survive the adverse effects of short-term anoxia. Due to their attached lifestyle, biochemical adaptations in bivalves are more diverse and more pronounced than in free-living organisms, which primarily have developed behavioral and physiological mechanisms to avoid short-term adverse environmental influences.

Several mechanisms for regulating metabolic levels have been described in marine mollusks. One of them is a change in the rate of glycolytic reactions. For example, Bivalvia is characterized by allosteric regulation of enzyme activity under anoxic conditions, during which metabolites affect specific enzyme loci. One of the important mechanisms for reducing the rate of general metabolism is reversible phosphorylation of proteins. Such changes in the structure of proteins cause significant modifications in the activity of many enzymes and functional proteins involved in all life processes of the body. For example, in Littorea littorea, as in most anoxia-tolerant mollusks, reversible phosphorylation of some glycolytic enzymes helps redirect carbon flow to the anaerobic pathway of enzymatic metabolism, as well as suppress the rate of the glycolytic pathway.

Although a decrease in metabolic rate is a quantitatively beneficial mechanism promoting the survival of marine mollusks under anoxic conditions, activation of modified metabolic pathways also plays an important role in the processes of adaptation of marine mollusks to low oxygen concentrations in seawater. During these reactions, the yield of ATP increases significantly and non-acidic and/or volatile end products are formed, which in turn contribute to maintaining cell homeostasis under anoxic conditions.

So, biochemical adaptation is often a last resort to which an organism resorts when it has no behavioral or physiological means to avoid the adverse effects of the environment.

Since biochemical adaptation is not an easy path, it is often easier for organisms to find a suitable environment through migration than to rebuild the chemistry of the cell. In the case of attached marine coastal bivalves, migration to favorable environmental conditions is impossible; therefore, they have well-developed metabolic regulation mechanisms that allow them to adapt to the constantly changing coastal zone of the sea, which is characterized by periodic drying.

Physiological mechanisms. Thermal adaptation is caused by a set of specific physiological changes. The main ones are increased sweating, a decrease in the temperature of the core and shell of the body, and a decrease in heart rate during exercise as the temperature increases (Table 1).

Table 1. Adaptive physiological changes in humans under conditions of elevated ambient temperature

	Changes
Sweating	A faster onset of sweating (during work), i.e., a decrease in the temperature threshold for sweating. Increased sweat rate
Blood and circulation	More even distribution of sweat over the surface of the body. Reduced salt content in sweat. Decreased heart rate. Increased skin blood flow. Increased systolic volume. Increased circulating blood volume. Decrease in the degree of working hemoconcentration. Faster redistribution of blood (to the skin vascular system). Bringing blood flow closer to the surface of the body and more efficiently distributing it over the surface of the body. Reducing the drop in celiac and renal blood flow (during work)
Thermoregulation	Reducing the temperature of the core and shell of the body at rest and during muscle work. Increased body resistance to elevated body temperature
	Reducing shortness of breath

Morpho-anatomical mechanisms. Thus, the well-known squirrel has good morphofunctional adaptability, which allows it to survive in its habitat. The adaptive external features of the protein structure include the following:

Sharp curved claws, allowing you to cling, hold and move well on wood;

Strong and longer hind legs than the front ones, which enable the squirrel to make large jumps;

A long and fluffy tail that acts like a parachute when jumping and warms her in the nest during the cold season;

Sharp, self-sharpening teeth, allowing you to chew hard food;

Shedding fur, which helps the squirrel not freeze in winter and feel lighter in summer, and also provides a change in camouflage color.

These adaptive features allow the squirrel to easily move through trees in all directions, find food and eat it, escape from enemies, make a nest and raise offspring, and remain a sedentary animal, despite seasonal temperature changes. This is how the squirrel interacts with its environment.

Behavioral mechanisms. In addition to examples of search activity for favorable habitats, learning, behavior strategies in conditions of threat (fight, flight, freezing), grouping, constant motivation by the interests of survival and procreation, another striking example can be given.

In natural and experimental conditions of the aquatic environment, both marine and freshwater fish species navigate using elements of behavior. In this case, both spatial and temporal adaptation to various factors occurs - temperature, illumination, oxygen content, flow speed, etc. Quite often, fish exhibit the phenomenon of spontaneous choice of one or another environmental factor, for example, orientation along the water temperature gradient. The behavioral mechanisms of fish orientation in relation to the temperature factor of the environment are often similar or slightly different from the reaction to other factors.

Ontogenetic mechanisms. Systems of ontogenetic adaptation are the foundation that ensures the survival and successful reproduction of a sufficient number of individuals in the habitat conditions familiar to the population. Their preservation is so important for the survival of species that in evolution a whole group of genetic systems arose that are designed to serve as a barrier protecting systems of ontogenetic adaptation from the destructive effects of those evolutionary factors that once contributed to their formation.

There are the following subtypes of this type of adaptation:

Genotypic adaptation - selection of hereditarily determined (change in genotype) increased adaptability to changed conditions (spontaneous mutagenesis);

Phenotypic adaptation - with this selection, variability is limited by the reaction norm determined by a stable genotype.

In dipterans, for which, thanks to the presence of giant polytene chromosomes of the salivary glands, it is possible to identify the fine linear structure of chromosomes, entire complexes of twin species are often found, consisting of several, almost morphologically indistinguishable, closely related species. For other zoological species that do not have polytene chromosomes, such a subtle cytological diagnosis is difficult, but even for them, on isolated archipelagos, entire groups of closely related species, clearly of recent origin, greatly diverged from a common continental ancestor, can often be observed. Classic examples are Hawaiian flowerbirds, Darwin's finches in the Galapagos Islands, lizards and snails in the Solomon Islands, and many other groups of endemic species. All this points to the possibility of multiple acts of speciation associated with single episodes of colonization, and to widespread adaptive radiation, the triggering mechanism of which was the destabilization of a previously stable, well-integrated genome.

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Ministry of Education and Science of the Russian Federation

Federal State Budgetary Educational Institution of Higher Education

"Bashkir State University"

Birsk branch

Faculty of Biology and Chemistry

Department of Biology and Ecology

Examination on the discipline

“Morpho-functional foundations of human adaptation”

on the topic of: “Adaptation of the body to various environmental conditions”

Completed:

master's student 2 years Tazeeva Lyubov Eduardovna

part-time education

Direction of training

06.04.01 Biology

Master's Program Ecology

• 1. Adaptation to low temperature
• 2. Adaptation to high temperature
• 3. Adaptation to the physical activity regime
• 3.1 Increased activity
• 3.2 Reduced activity
• 4. Adaptation to hypoxia
• 5. Adaptation to weightlessness
• Bibliography

1. Adaptation to low temperature

The human body temperature, like that of any homeothermic organism, is characterized by constancy and fluctuates within extremely narrow limits. These limits range from 36.4 C to 37.5 C.

The conditions under which the body must adapt to cold can be different and are not limited to staying in a region with a cold climate.

In this case, the cold does not act around the clock, but alternates with the normal temperature regime for a given person. The adaptation phases in such cases are usually blurred. In the first days, in response to low temperatures, heat production increases uneconomically, excessively, heat transfer is still not sufficiently limited. After establishing a phase of stable adaptation, the processes of heat production become more intense, and heat transfer decreases and, ultimately, are balanced in such a way as to most perfectly maintain a stable body temperature in new conditions. It should be noted that active adaptation in this case is joined by mechanisms that ensure adaptation of receptors to cold, that is, an increase in the threshold of stimulation of these receptors. This mechanism of blocking the effects of cold reduces the need for active adaptive reactions.

Adaptation to life in northern latitudes proceeds differently. Here the effects on the body are always complex; Once in the conditions of the North, a person is exposed not only to low temperature, but also to altered light conditions and radiation levels. At present, when the need to develop the Far North is becoming more and more urgent, the mechanisms of adaptation to the North, i.e. acclimatization, are being thoroughly studied.

It has been established that the first acute adaptation upon arrival in the North is marked by an unbalanced combination of heat production and heat transfer. Under the influence of relatively quickly established regulatory mechanisms, persistent changes in heat production develop, which are adaptive for survival in new conditions. It has been shown that after the “emergency” stage, stable adaptation is achieved due to changes, in particular, in enzymatic antioxidant systems. We are talking about enhancing lipid metabolism, which is beneficial for the body to intensify energy processes. People living in the North have increased levels of fatty acids in their blood, while their blood sugar levels are reduced. Due to the increase in “deep” blood flow with the narrowing of peripheral vessels, fatty acids are more actively washed out of adipose tissue. Mitochondria in the cells of people adapted to life in the North also include fatty acids. This leads to a change in the nature of oxidative reactions, to the separation of phosphorylation and free oxidation. Of these two processes, free oxidation becomes dominant. There are relatively many free radicals in the tissues of northern residents.

The formation of specific changes in tissue processes characteristic of adaptation is facilitated by nervous and humoral mechanisms. In particular, under cold conditions, manifestations of increased activity of the thyroid gland (thyroxine ensures an increase in heat production) and adrenal glands (catecholamines provide a catabolic effect) have been well studied. These hormones also stimulate lipolytic reactions. It is believed that in the conditions of the North, ACTH and adrenal hormones are produced especially actively, causing the mobilization of adaptation mechanisms and increasing the sensitivity of tissues to thyroxine.

The formation of adaptation and its wave-like course are associated with symptoms such as lability of mental and emotional reactions, fatigue, shortness of breath and other hypoxic phenomena. In general, these symptoms correspond to the “polar tension” syndrome. It is believed that cosmic radiation plays an important role in the development of this condition. In some people, with irregular stress in the conditions of the North, the defense mechanisms and adaptive restructuring of the body can cause a breakdown - disadaptation. In this case, a number of pathological phenomena called “polar disease” appear.

2. Adaptation to high temperature

High temperature can affect the human body in different situations. Adaptation mechanisms are aimed at increasing heat transfer and reducing heat production. As a result, body temperature (although rising) remains within the upper limit of the normal range. The manifestations of hyperthermia are largely determined by the ambient temperature.

When the external temperature rises to +30-31C, the skin arteries expand and the blood flow in it increases, and the temperature of the surface tissues increases. These changes are aimed at the body releasing excess heat through convection, heat conduction and radiation, but as the ambient temperature increases, the effectiveness of these heat transfer mechanisms decreases.

At an external temperature of +32-33C and above, convection and radiation stop. Heat transfer through sweating and evaporation of moisture from the surface of the body and respiratory tract takes on leading importance. So, with 1 ml of sweat, approximately 0.6 kcal of heat is lost.

During hyperthermia, characteristic changes occur in organs and functional systems. Sweat glands secrete kallikrein. This leads to the formation of kallidin, bradykinin and other kinins in the blood. Kinins, in turn, provide dual effects: expansion of arterioles of the skin and subcutaneous tissue; potentiation of sweating. These effects of kinins significantly increase the heat transfer of the body.

Due to the activation of the sympathoadrenal system, heart rate and cardiac output increase.

There is a redistribution of blood flow with the development of its centralization.

There is a tendency to increase blood pressure.

Further adaptation occurs due to a decrease in heat production and the formation of a stable redistribution of blood supply to the vessels. Excessive sweating turns into adequate sweating at high temperatures. Loss of water and salts through sweat can be compensated by drinking salted water.

3. Adaptation to the physical activity regime

Often, under the influence of any environmental requirements, the level of physical activity changes towards its increase or decrease.

3.1 Increased activity

Motor activity is the main property of animals and humans, an integral part of the life and development of each organism. During life, often under the influence of any requirements of the external environment, the level of physical activity changes in the direction of its increase or decrease.

If a person changes his lifestyle so that his physical activity becomes high, then his body must adapt to the new state. In these cases, a specific adaptation develops, which boils down to the restructuring of muscle tissue, or rather its mass, in accordance with the increased function.

This mechanism is based on the activation of muscle protein synthesis. An increase in their function per unit of tissue mass causes a change in the activity of the genetic apparatus, which leads to an increase in the number of ribosomes and polysomes in which protein synthesis occurs. Ultimately, cellular proteins grow in volume and quantity, the mass of muscle tissue increases, in other words, hypertrophy occurs. At the same time, the use of pyruvate in the mitochondria of muscle cells increases, which prevents an increase in lactate in the blood and ensures the mobilization and use of fatty acids, and this, in turn, leads to an increase in performance. As a result, the volume of the function comes into line with the volume of the organ structure, and the body as a whole becomes adapted to the load of this magnitude. If a person carries out intensive training in a volume significantly exceeding physiological, then the structure of the muscles undergoes especially pronounced changes. The volume of muscle fibers increases to such an extent that the blood supply cannot cope with the task of providing such a high supply to the muscles. This leads to the opposite result: the energy of muscle contractions weakens. This phenomenon can be considered maladaptation.

In general, well-dosed muscle loads help increase nonspecific resistance to the action of a variety of factors. Sometimes humans and animals are forced to adapt to reduced motor activity - hypokinesia.

3.2 Reduced activity

Restrictions on the motor activity of a living organism are called hypokinesia (a synonym for the term “hypodynamia”).

The degree of hypokinesia in natural conditions and in experience can be different - from a slight limitation of mobility to its almost complete cessation. Complete hypokinesia can only be achieved using pharmacological substances such as myorelaxin.

We can talk about different types of hypokinesia. These include: no need for movement; inability to move due to the specific external conditions; prohibition of movements during rest mode due to illness; inability to move due to illness.

An example of hypokinesia, associated with a lack of need for physical activity, is the routine of our daily life. Of course, we are talking about people engaged in mental work, leading a so-called “sedentary lifestyle.” However, modern highly developed technology used in production leads to the fact that workers and peasants in the process of work make less and less physical effort, as human labor is gradually replaced by the work of various machines. Thus, the scientific and technological revolution brings with it hypokinesia, which is a negative point for humans as a biological system.

The emergency phase of adaptation to hypokinesia is characterized by the initial mobilization of reactions that compensate for the lack of motor functions.

The body's reaction to hypokinesia primarily involves the nervous system with its reflex mechanisms. By interacting with humoral mechanisms, the nervous system organizes protective adaptation reactions to the effects of hypokinesia.

Research has shown that such protective reactions include excitation of the sympathoadrenal system, mostly associated with emotional stress during hypokinesia. Secondly, protective reactions include adaptation hormones.

The sympathoadrenal system causes temporary partial compensation of circulatory disorders in the form of increased cardiac activity, increased vascular tone and, consequently, blood pressure, increased respiration (increased ventilation of the lungs). The release of adrenaline and stimulation of the sympathetic system contribute to an increase in the level of catabolism in tissues. However, these reactions are short-lived and quickly fade away with continued hypokinesia.

The further development of hypokinesia can be imagined as follows. Immobility helps, first of all, to reduce catabolic processes. The release of energy decreases, and the intensity of oxidative reactions becomes insignificant. Since the content of carbon dioxide, lactic acid and other metabolic products in the blood that normally stimulate respiration and blood circulation (heart rate, blood flow speed and blood pressure) decreases, these indicators also decrease. In people in a state of hypokinesia, ventilation of the lungs decreases, the heart rate drops, and blood pressure becomes lower.

If the nutrition remains the same as during vigorous activity, a positive balance is observed, the accumulation of fats and carbohydrates in the body. With continued hypokinesia, such excess assimilation quite soon leads to obesity.

The cardiovascular system undergoes characteristic changes. Constant underload of the heart due to a decrease in venous return to the right atrium causes underexpansion of the heart with blood, a decrease in cardiac output. The heart muscle begins to work weakened. In the fibers of the heart muscle, the intensity of oxidative reactions decreases, and this leads to a change like atrophy (the word “atrophy” means lack of nutrition). Muscle mass decreases, their energy potential decreases, and, finally, destructive changes occur.

In experiments on rabbits exposed to hypokinesia for a long time, it was found that the heart of the experimental rabbit decreased in volume by 25% compared to the heart of a rabbit from the control group. Similar results were obtained by N.A. Agadzhanyan (1962) in subjects after a 60-day stay in closed chambers of small volume.

Changes also occur in the vascular system. Under conditions of hypokinesia, when the ejection of blood from the heart decreases and the amount of circulating blood decreases due to its deposition and stagnation in the capillaries, the tone of the heart gradually weakens. This lowers blood pressure, which, in turn, leads to poor oxygen supply to tissues and a drop in the intensity of metabolic reactions in them (vicious circle).

Stagnation of blood in the capillaries and capacitive part of the vascular bed - small veins - contributes to an increase in the permeability of the vascular wall for water and electrolytes and their sweating into the tissue. As a result, swelling of various parts of the body occurs. Weakening of the heart causes an increase in pressure in the vena cava system, which, in turn, leads to stagnation in the liver. The latter helps to reduce its metabolic, barrier and other functions that are very important for the body’s condition. In addition, poor blood circulation in the liver causes stagnation of blood in the portal vein. This results in an increase in pressure in the capillaries of the intestinal wall and a decrease in the absorption of substances from the intestine.

Deterioration of blood circulation in the digestive system reduces the intensity of juice secretion, resulting in digestive disorders. A decrease in blood pressure and circulating blood volume causes a decrease in urine production in the kidneys. This increases the content of residual nitrogen in the body, which is not excreted in the urine.

4. Adaptation to hypoxia

When oxygen starvation occurs, a protective mechanism awakens in the body, working towards eliminating or reducing the severity of hypoxia.

These processes appear already at the earliest stage of hypoxia. Such adaptation mechanisms are called emergency. If the disease becomes chronic, the process of organ adaptation to hypoxia becomes more complex and lengthy.

Emergency adaptation consists of transporting oxygen and metabolic substrates and turning on tissue metabolism.

Long-term adaptation occurs more slowly and includes adjustments in the functions of the pulmonary alveoli, pulmonary ventilation blood flow, compensatory myocardial enlargement, bone marrow hyperplasia, and hemoglobin accumulation.

Classification of hypoxia.

Based on the duration and intensity of the course, functional, destructive and metabolic hypoxia are distinguished.

Destructive hypoxia is a severe form and leads to irreversible changes in the body.

Functional hypoxia occurs when hemodynamics are impaired, i.e. as a result of impaired blood flow for various reasons, for example, hypothermia, injuries, burns, etc.

Metabolic hypoxia develops as a result of impaired oxygen supply to tissues. At the same time, a change in metabolic processes occurs in them.

Both functional and metabolic hypoxia are reversible. This means that after the necessary treatment or changes in the factors causing hypoxia, all processes in the body are restored.

Based on the causes of occurrence, hypoxia is divided into:

Exogenous hypoxia, depending on the partial pressure of oxygen. This type includes high-altitude hypoxia, which develops at low atmospheric pressure, for example in the mountains. High-altitude hypoxia can occur in a confined space - a mine, an elevator, a submarine, etc. The causes of high-altitude hypoxia are a decrease in the content of oxygen and carbon dioxide CO2 in the blood, leading to an increase in the frequency and depth of breathing.

- respiratory hypoxia that occurs against the background of respiratory failure.

- histotoxic hypoxia caused by improper use of oxygen by tissues.

- hemic, which occurs with anemia and suppression of hemoglobin by carbon monoxide or oxidizing agents.

- circulation hypoxia, which develops with circulatory failure accompanied by arteriovenous oxygen deficiency.

- overload, the development of which is caused by attacks of epilepsy, stress from hard work, etc. similar reasons.

Technogenic hypoxia occurs when a person constantly stays in an environmentally unsatisfactory environment.

Brain hypoxia and neonatal hypoxia are often encountered in medical practice.

Brain hypoxia disrupts the activity of the entire body and primarily the central nervous system.

Hypoxia in newborns occurs quite often in obstetric and gynecological practice and has serious consequences. The main causes of chronic fetal hypoxia are maternal diseases such as diabetes mellitus, anemia, occupational intoxication, heart defects and other diseases.

The causes of chronic fetal hypoxia include complicated pregnancy caused by a disorder of the uteroplacental circulation. In addition, pathological development of the fetus in the form of malnutrition, Rh conflict, infection of the fetus when protective barriers are broken, and multiple births can also be causes of chronic fetal hypoxia.

Signs of hypoxia.

Symptoms of oxygen starvation are expressed by constant fatigue and depression, accompanied by insomnia.

There is deterioration in hearing and vision, headaches and chest pain. The electrocardiogram reveals sinus arrhythmia. Patients experience shortness of breath, nausea and spatial disorientation. Breathing may be heavy and deep.

In the initial stage of development of cerebral hypoxia, its signs are expressed by high energy, turning into euphoria. Self-control over motor activity is lost. Signs of cerebral hypoxia may include an unsteady gait, palpitations, pallor bordering on cyanosis, or, conversely, the skin becomes dark red.

In addition to those common to all, signs of cerebral hypoxia, as the disease progresses, are expressed by fainting, cerebral edema, and lack of skin sensitivity. Often this condition ends in coma with a fatal outcome.

Any type of hypoxia requires immediate treatment based on eliminating its cause.

temperature adaptation hypoxia weightlessness

5. Adaptation to weightlessness

Conditions of weightlessness are the most inadequate for the body.

A person is born, grows and develops only under the influence of the forces of gravity. The force of gravity forms the topography of the functions of skeletal muscles, and gravitational reflexes, as well as coordinated muscle work.

Autonomic support of muscle activity also largely depends on the force of gravity. In particular, blood circulation is based on the force of gravity. The force of gravity promotes the flow of blood through the arteries, but prevents the flow of blood through the veins, and therefore the body develops mechanisms that promote venous blood flow.

When gravity changes, various changes are observed in the body, determined by the elimination of hydrostatic pressure and redistribution of body fluids, the elimination of gravity-dependent deformation and mechanical stress of body structures, as well as a decrease in the functional load on the musculoskeletal system, the elimination of support, and changes in the biomechanics of movements.

When a person finds himself in conditions of weightlessness during space flight, this dramatically disrupts both somatic activity and the functioning of internal organs. Extero- and interoreceptors begin to signal an unusual state of skeletal muscles and all internal organs.

Under the influence of such unusual impulses, during the acute adaptation phase, a high degree of disorganization of motor activity and the functioning of internal organs is noted.

The disorganization of functions is deep and tends to progress. It is characterized by a change in the regional status of the vascular system. As a result, during the acute period of adaptation, there is a rush of blood to the head. A number of vestibular disorders, changes in metabolism, which manifests itself in a decrease in the level of energy metabolism.

In severe conditions, there is a violation of mineral, including calcium, metabolism, which depends on motor activity in conditions of underload of the skeletal system of the extremities, especially the lower ones. Apparently, the negative balance of Ca2+ ions under space flight conditions may also be associated with endocrine shifts. Not only the coordination of movements changes, but even the handwriting. The experiments revealed disturbances in the structure of the anterior horns of the gray matter of the spinal cord, and also showed a decrease in the stability of physiological systems under conditions of physical activity. Adaptation under these conditions is possible only with a radical restructuring of the control mechanisms of the central nervous system, the formation of functional systems with the mandatory use of a set of technical and training protective measures. It is necessary to use various artificial methods of life support in such an unusual and inadequate situation for the body.

As a result, hypogravity motor syndrome is formed, which includes changes in 1) sensory systems, 2) motor control, 3) muscle function, 4) hemodynamics.

1) Changes in the operation of sensory systems:

- decrease in the level of supporting afferentation;

- decreased level of proprioceptive activity;

- change in the function of the vestibular apparatus;

- change in afferent support of motor reactions;

- disorder of all forms of visual tracking;

- functional changes in the activity of the otolithic apparatus when the position of the head changes and the action of linear accelerations.

2) Change in motor control:

- sensory and motor ataxia;

- spinal hyperreflexia;

- change in movement control strategy;

- increasing the tone of the flexor muscles.

3) Change in muscle functioning:

- decrease in speed and strength properties;

- atony;

- atrophy, changes in the composition of muscle fibers.

4) Hemodynamic disorders:

- increased cardiac output;

- decreased secretion of vasopressin and renin;

- increased secretion of natriuretic factor;

- increased renal blood flow;

- decrease in blood plasma volume.

The possibility of true adaptation to weightlessness, in which a restructuring of the regulatory system occurs, adequate to existence on Earth, is hypothetical and requires scientific confirmation.

Bibliography

2. Grigoriev A.I. Human ecology. - M.: GEOTAR-Media, 2008. - 240 s.

3. Agadzhanyan N.A., Tel L.Z., Tsirkin V.I., Chesnokova S.A. Human physiology. - M,: Medical Book, 2009. - 526 p.

4. N.A. Agadzhanyan, A.I. Volozhin, E.V. Evstafieva. Human ecology and survival concept. - M.: GOU VUNMC Ministry of Health of the Russian Federation, 2001. - 240 p.

5. L.I. Tsvetkova, M.I. Alekseev and others; Ed. L.I. Tsvetkovoy Ecology: Textbook for technical universities. - M.: Publishing house ASV; St. Petersburg: Khimizdat, 1999. - 488 p.

6. Kormilitsyn V.I., Tsitskishvili M.S., Yalamov Yu.I. Fundamentals of ecology: Textbook / - M.: MPU, 1997. 1 - 368 p.

7. Zakharov V.B., Mamontov S.G., Sivoglazov V.I. “Biology: general patterns”: Textbook for grades 10 - 11. general education institutions. - M.: Shkola-Press, 1996. - 625 p.

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Concept, classifications, characteristics of hypoxia. Adaptive reactions and mechanisms of long-term adaptation to hypoxia. Metabolic disorders, functions of organs and tissues during hypoxia. Prevention and therapy of hypoxia. Toxic effects of excess oxygen.

Adaptation– this is the adaptation of the organism to environmental conditions due to a complex of morphological, physiological, and behavioral characteristics.

Different organisms adapt to different environmental conditions, and as a result, moisture-loving hydrophytes and "dry-bearers" - xerophytes(Fig. 6); plants of saline soils – halophytes; shade tolerant plants ( sciophytes), and requiring full sunlight for normal development ( heliophytes); animals that live in deserts, steppes, forests or swamps are nocturnal or diurnal. Groups of species with a similar relationship to environmental conditions (that is, living in the same ecotopes) are called environmental groups.

The ability of plants and animals to adapt to unfavorable conditions differs. Due to the fact that animals are mobile, their adaptations are more diverse than those of plants. Animals can:

– avoid unfavorable conditions (birds fly to warmer regions due to lack of food and cold in winter, deer and other ungulates wander in search of food, etc.);

– fall into suspended animation – a temporary state in which life processes are so slow that their visible manifestations are almost completely absent (numbness of insects, hibernation of vertebrates, etc.);

– adapt to life in unfavorable conditions (they are saved from frost by their fur and subcutaneous fat, desert animals have adaptations for economical use of water and cooling, etc.). (Fig. 7).

Plants are inactive and lead an attached lifestyle. Therefore, only the last two adaptation options are possible for them. Thus, plants are characterized by a decrease in the intensity of vital processes during unfavorable periods: they shed their leaves, overwinter in the form of dormant organs buried in the soil - bulbs, rhizomes, tubers, and remain in the state of seeds and spores in the soil. In bryophytes, the entire plant has the ability to undergo anabiosis, which can survive for several years in a dry state.

Plant resistance to unfavorable factors increases due to special physiological mechanisms: changes in osmotic pressure in cells, regulation of the intensity of evaporation using stomata, the use of “filter” membranes for selective absorption of substances, etc.

Adaptations develop at different rates in different organisms. They arise most quickly in insects, which in 10–20 generations can adapt to the action of a new insecticide, which explains the failure of chemical control of the density of insect pest populations. The process of developing adaptations in plants or birds occurs slowly, over centuries.

Observed changes in the behavior of organisms are usually associated with hidden characteristics that they had, as it were, “in reserve,” but under the influence of new factors they emerged and increased the stability of the species. Such hidden characteristics explain the resistance of some tree species to industrial pollution (poplar, larch, willow) and some weed species to herbicides.

The same ecological group often includes organisms that are not similar to each other. This is due to the fact that different types of organisms can adapt differently to the same environmental factor.

For example, they experience the cold differently warm-blooded(they are called endothermic, from the Greek words endon - inside and terme - heat) and cold-blooded (ectothermic, from the Greek ektos - outside) organisms. (Fig. 8.)

The body temperature of endothermic organisms does not depend on the ambient temperature and is always more or less constant, its fluctuations do not exceed 2–4 o even in the most severe frosts and extreme heat. These animals (birds and mammals) maintain body temperature by internal heat generation based on intensive metabolism. They retain their body heat through warm “coats” made of feathers, wool, etc.

Physiological and morphological adaptations are complemented by adaptive behavior (choosing sheltered places to spend the night, building burrows and nests, group overnight stays with rodents, close groups of penguins keeping each other warm, etc.). If the ambient temperature is very high, then endothermic organisms are cooled due to special devices, for example, by evaporation of moisture from the surface of the mucous membranes of the oral cavity and upper respiratory tract. (For this reason, in hot weather, the dog’s breathing quickens and he sticks out his tongue.)

The body temperature and mobility of ectothermic animals depends on the ambient temperature. In cool weather, insects and lizards become lethargic and inactive. Many species of animals have the ability to choose a place with favorable conditions of temperature, humidity and sunlight (lizards bask on illuminated rock slabs).

However, absolute ectothermism is observed only in very small organisms. Most cold-blooded organisms are still capable of weak regulation of body temperature. For example, in actively flying insects - butterflies, bumblebees, body temperature is maintained at 36–40 o C even at air temperatures below 10 o C.

Similarly, species of one ecological group in plants differ in their appearance. They can also adapt to the same environmental conditions in different ways. Thus, different types of xerophytes save water in different ways: some have thick cell membranes, others have pubescence or a waxy coating on the leaves. Some xerophytes (for example, from the family Lamiaceae) emit vapors of essential oils that envelop them like a “blanket”, which reduces evaporation. The root system of some xerophytes is powerful, goes into the soil to a depth of several meters and reaches the groundwater level (camel thorn), while others have a superficial but highly branched one, which allows them to collect precipitation water.

Among the xerophytes there are shrubs with very small hard leaves that can be shed in the driest time of the year (caragana shrub in the steppe, desert shrubs), turf grasses with narrow leaves (feather grass, fescue), succulents(from the Latin succulentus - succulent). Succulents have succulent leaves or stems that store water, and can easily tolerate high air temperatures. Succulents include American cacti and saxaul, which grows in Central Asian deserts. They have a special type of photosynthesis: the stomata open briefly and only at night; during these cool hours, plants store carbon dioxide, and during the day they use it for photosynthesis with the stomata closed. (Fig. 9.)

A variety of adaptations to surviving unfavorable conditions on saline soils is also observed in halophytes. Among them there are plants that are capable of accumulating salts in their bodies (saltweed, swede, sarsazan), secreting excess salts onto the surface of the leaves with special glands (kermek, tamarix), “not allowing” salts into their tissues due to the “root barrier” impermeable to salts "(wormwood). In the latter case, the plants have to be content with a small amount of water and they have the appearance of xerophytes.

For this reason, one should not be surprised that in the same conditions there are plants and animals that are dissimilar to each other, which have adapted to these conditions in different ways.

Control questions

1. What is adaptation?

2. How can animals and plants adapt to unfavorable environmental conditions?

2. Give examples of ecological groups of plants and animals.

3. Tell us about the different adaptations of organisms to surviving the same unfavorable environmental conditions.

4. What is the difference between adaptations to low temperatures in endothermic and ectothermic animals?

Adaptations – various adaptations to the environment developed in organisms during the process of evolution. Adaptations manifest themselves at different levels of organization of living matter: from molecular to biocenotic. The ability to adapt is one of the main properties of living matter, ensuring the possibility of its existence. Adaptations develop under the influence of three main factors: heredity, variability and natural (as well as artificial) selection.

There are three main ways that organisms adapt to environmental conditions: the active path, the passive path, and the avoidance of adverse effects.

Active path – strengthening resistance, development of regulatory processes that allow all vital functions of the body to be carried out, despite factor deviations from the optimum. For example, maintaining a constant body temperature in warm-blooded animals (birds and mammals), optimal for the occurrence of biochemical processes in cells.

Avoidance of Adverse Effects – development by the body of such life cycles and behavior that allow one to avoid adverse effects. For example, seasonal migrations of animals.

Passive way – subordination of the vital functions of the body to changes in environmental factors. Rest can vary in depth and duration; many functions of the body weaken or are not performed at all, since the level of metabolism falls under the influence of external and internal factors. With deep suppression of metabolism, organisms may not show visible signs of life at all. The complete temporary stoppage of life is called suspended animation . In a state of suspended animation, organisms become resistant to various influences. In a dry state, when no more than 2% of water remained in the cells in a chemically bound form, organisms such as rotifers, tardigrades, small nematodes, seeds and spores of plants, spores of bacteria and fungi withstood exposure to liquid oxygen (-218.4 ° C ), liquid hydrogen (-259.4 °C), liquid helium (-269.0 °C). All metabolism is stopped. Anabiosis is a rather rare phenomenon and is an extreme state of rest in living nature; the state of suspended animation is possible only with almost complete dehydration of organisms. Other forms of dormancy associated with a state of decreased vital activity as a result of partial inhibition of metabolism are much more widespread in nature. Forms of rest in a state of decreased vital activity are divided into hypobiosis (forced peace) And cryptobiosis(physiological rest) . At hypobiosis inhibition of activity, or torpor, occurs under the direct pressure of unfavorable conditions (lack of heat, water, oxygen, etc.) and stops almost immediately after these conditions return to normal (some frost-resistant species of arthropods (collembolas, a number of flies, ground beetles, etc.) overwinter in a state of torpor, quickly thawing and switching to activity under the rays of the sun, and then again lose mobility when the temperature drops). Cryptobiosis- a fundamentally different type of rest, it is associated with a complex of physiological changes that occur in advance, before the onset of unfavorable seasonal changes, and organisms are ready for them. Cryptobiosis is widespread in living nature (characteristic, for example, of plant seeds, cysts and spores of various microorganisms, fungi, algae, mammalian hibernation, deep plant dormancy). The states of hypobiosis, cryptobiosis and anabiosis ensure the survival of species in natural conditions of different latitudes, often extreme, allow the preservation of organisms during long unfavorable periods, settle in space and in many ways push the boundaries of the possibility and distribution of life in general.

Typically, adaptation of a species to its environment is carried out by one or another combination of all three possible adaptation paths.

Basic mechanisms of adaptation at the organism level:

Biochemical adaptations– changes in intracellular processes (for example, a change in the work of enzymes or a change in their quantity).

Morpho-anatomical adaptations – changes in the structure of the body (for example, modification of a leaf into a spine in cacti to reduce water loss, bright coloring of flowers to attract pollinators, etc.). Morphological adaptations in plants and animals lead to the formation of certain life forms.

Physiological adaptations – changes in the physiology of the body (for example, the ability of a camel to provide the body with moisture by oxidizing fat reserves, the presence of cellulose-degrading enzymes in cellulose-degrading bacteria, etc.).

Ethological (behavioral) adaptations – changes in behavior (for example, seasonal migrations of mammals and birds, hibernation in winter, mating displays in birds and mammals during the breeding season, etc.). Ethological adaptations are characteristic of animals.

Ontogenetic adaptations– acceleration or deceleration of individual development, promoting survival when conditions change.