Each organism lives, develops and effectively multiplies in a certain ambient temperature range. On the temperature scaleThus, you can specify two points that determine the zone of life of this species, called the temperature tolerance zone, and the zone of lethal temperatures outside the tolerance zone. Points that limit the zone of temperature tolerance are called critical. They are determined on the basis of mortality data on the border of the tolerance zone. In the boundaries of the temperature tolerance zone and abroad, there are a number of characteristic manifestations or reactions of the body. The center of the tolerance zone is thermal optimum, in the boundaries of which all processes of vital activity proceed most economically. In the high temperature band, the temperature of the temperature cobster occurs. Further increase in temperature leads to overheating of the body and his death. At temperatures below, the optimal body enters the unfavorable zone where it takes place from the cold. A further decrease in temperature, in particular the transition through 00, causes the supercooling of body fluids from the beginning, after which, depending on the degree of salt concentration in these liquids, the body reaches the point of critical temperature. At this point, the freezing of body fluids begins, and the temperature of the body from the beginning rise briefly, after which the slow freezing of body fluids occurs, and the body goes into an anabea state. The complete freezing of body fluids leads to death. The death of low temperatures depends on the development stage of the body.
In humans, normal life is possible in the range of just a few degrees: a decrease in body temperature below 360s and the increase above 40-410C is dangerous and may have severe consequences for the body (freezing, thermal blow).
The sensation of ambient temperature depends on the temperature of the skin, which, at the temperature of the environment, 32-350c does not feel neither supercooling or overheating. The perception of temperature conditions of the medium is associated with the daily rhythm of human metabolism and related conditions. Temperature comfort area for man is 17-270c. The subjective feeling of climatic comfort is associated with the level of human activity, radiation temperature, clothing, temperature and relative humidity, as well as wind speed. In apartments where the air movement does not have great importance, the conditions of heat exchange and human well-being are determined by temperature conditions and humidity. High humidity compensates for lower temperature.
The ambient temperature, affecting the body through the body surface receptors, changes the focus of many physiological mechanisms of the body. The decrease in temperature is accompanied by an increase in excitability nervous system, as well as the strengthening of the secretion of adrenal hormones. The level of main exchange is increasing. The total and local hypothermia causes the churring and mucous membranes, inflammation of the walls of vessels and nerve trunks. Cooling during pathess, sharp temperature differences and deep cooling of the internal organs lead to colds.
The effect of low temperatures per person is intensified under the action of wind. The joint action of the wind and cold is especially susceptible to arms and legs, which are often open even in conditions harsh winter. Of the three parts of the face: forehead, cheeks and nasal - the most sensitive is the forehead, which in normal conditions is one of the warmest areas of the body surface.
Facility to cold in humans is provided in various ways. Critical temperature for Europeans without clothes enclosed within 270 to 290c. With a decrease in temperature below the critical European reacts to an increase in metabolism. However, the indigenous people of Australia, especially in its central and southern parts, sleep at night, not covered by the body. With night supercooling, insulating hypothermia occurs in sleeping aborigines. It consists in cooling the surface of the body by several degrees without metabolic reactions, which leads to a decrease in heat loss. Such adaptation, however, is absent from Eskimos living in the coldest Arctic areas. They are inherent in European-type metabolic adaptations. This is due to the nature of clothing, which perfectly protects their body from the ambient temperature reaching - 500c.
Thus, in a person when adapting to cold, various types of metabolism are rebuilt, hypertrophied adrenal glands are preserved. A superficial layer of open areas of leather is compacted, the fat layer increases, brown fat is deposited in the cooled places. In the reaction of adaptation to cold, all physiological systems of the body are involved. The overall metabolism increases, the function of the thyroid gland, the blood circulation of the brain, heart muscle, liver, increases the number of catecholamines. This increase in metabolic reactions creates a reserve of the body's existence at low temperatures.
With increasing temperature, the main exchange in humans is reduced. The first respiratory and cardiovascular system react. Significant temperature increase causes peripheral expansion blood vessels, the increase in pulse and respiration, an increase in the minute volume of blood and decrease in blood pressure. Blood flow in muscles and in internal organs decreases. Also falls the excitability of the nervous system.
Human resistance to heat is significantly higher than the exposure to cold, which is due to the release of sweat. This process can remove energy from the human body, 14 times the magnitude of its production in metabolism is at rest. Thus, the effectiveness of thermoregulation by means of sweat is huge.
In case of a sudden increase in the temperature of the environment, the human body responds to relaxation and the impossibility of performing tasks normally carried out at a slightly lower temperatures. There is a desire to get rid of clothes, strong sweating and increased irritability. The device to elevated temperatures lasts, as a rule, several days and consists in increasing the body temperature, slowing the rhythm of cardiac activity and the increase in sweating.
If the temperature of the external environment reaches 27-380s (blood temperature), the heat transfer is carried out mainly due to the sweating. In the case of its difficulty with high humidity of the environment, the organism overheating occurs. This is accompanied by an increase in body temperature, impaired input and salt metabolism and vitamin equilibrium. The formation of non-oprified metabolic products occurs. Blood thickening begins. When overheating, blood circulation and respiration can occur. Initially there is an increase, and then drop blood pressure. With repeated high temperatures, there is an increase in tolerance to thermal factors. The change in the ambient temperature aside from the temperature of the temperature comfort when disrupting adaptation is accompanied by a violation of the processes of self-regulation and the occurrence of pathological reactions.
The main form of protection of the body from overheating is cool clothing - light, well ventilated, long, with folds. It reduces the absorption of radiation energy by half, and water loss - up to 2/3.
To protect against temperature factor in the structure of many animals there are special devices. So, in a number of insects, good thermal insulation provides thick cover of hairs on the chest department: between the hairs is a layer of motionless air that reduces heat transfer. Tuns can maintain the temperature of their muscles at 8 - 10 0 C above the water temperature due to the presence of special heat exchangers - the close interlacing of arterial and venous capillaries, for which the artery comes from the gills and from the muscles to the Zhabra Vienna. The first bonds are chilled by water, the second - warmed by working muscles. In the heat exchanger, venous blood gives heat arterial, which helps to maintain a higher temperature in the muscles. W. aqueous mammals The thermal insulation is the thick layer of subcutaneous fat, and the White Bear, in addition, and the wool waterproof to the skin. In waterfowl, the same role is played by feathers covered with a leafy lubricant.
A major German zoologist and founder of the world famous Hamburg Zoological Garden K. Gazenbeck tells in his memories of this lubricant. He from childhood was fond of animals. Once the father gave him a few wild ducks With cropped wings, so they could not fly away. And the little Karl let them swim in a metal tank. But the tank was from under fuel oil, in which the ducks smeared from the legs to the head. Seeing such a disorder, the boy thoroughly washed the ducks with warm water with soap and let them swim in another, pure tank. The next morning, all the ducks lay dead at the bottom: warm water And soap removed not only fuel oil, but also all fat lubrication, as a result of which the ducks were drowned and died.
We already know that homoothermal animals can maintain the body temperature in a much larger temperature range than causticothers, however, those and others are dying with approximately the same excessively high or excessive temperatures. But until it happened, until the temperature has reached critical values, the body struggles for maintaining it to PA normal or at least close to normal level. Naturally, it is fully characteristic of homoothermal organisms with thermoregulation capable of strengthening or weakening both heat-producing and heat transfer. The heat transfer is the process of purely physiological, it occurs on the organ and organisal levels, and physiological, chemical, and molecular mechanisms are also based on heat product. First of all, it is chills, cold trembling, i.e. Small cuts of skeletal muscles with a low efficiency and increased formation of heat. This mechanism the body includes automatically, reflexively. Its effect can be increased active arbitrary muscle activity, also enhancing heat generation. It is not by chance to warm up, we resort to movement.
Gomeothermal has the possibility of heat formation and without cutting muscles. This is mainly in the muscles, as well as in the liver and other organs as follows. With the transport of electrons and protons along the respiratory chain, the energy of oxidized substances is not dissipated in the form of heat, and is captured in the form of macro-erochic compounds that provide Resintez ATP. The effectiveness of this process opened by an outstanding biochemist V.A. Engelgardt and the resulting respiratory phosphorylation, is measured by the P / O coefficient, showing how many phosphorus atoms were included in ATP per atom of oxygen used by mitochondria. Under normal conditions, depending on which substance is oxidized, this coefficient is varied by two or three. When cooling the body, oxidation and phosphorylation are partially divided. The OLI of the other part of the oxidized substances joins the path of "free" oxidation, as a result of which the formation of ATP is reduced and heat is increased. At the same time, naturally, the R / O coefficient decreases. Disagreement This is achieved by the effect of thyroid hormone and free fatty acids, in elevated amounts entering blood and bring it to the muscles and other organs. With an increase in the external temperature, on the contrary, the conjugation of oxidation and phosphorylation is enhanced, and heat-product is reduced.
In addition to muscles and liver, for which heat generation is not the main, but by the side function, in the organism of mammalian animals there is a special organ of heat products - brown tissue fabric. It is located near the heart and on the path of blood to vital important organs: heart, brain, kidneys. Its cages are extremely rich in mitochondria, and the oxidation of fatty acids is very intensively intensively. But it is not conjugate with phosphorylation ADP, and the energy of oxidized substances is released from them "in the form of heat. The amplifier of oxidative processes in the brown tissue is adrenaline, and the respiratory disabel and phosphorylation - the resulting in it large quantities fatty acid.
An interesting mechanism for maintaining the muscle temperature was recently opened at the bumblebees of famous English biochemist E. Newsholm. In all animals, the fructo-phosphate formed in the process of glycolysis, connecting from ATP another particle of phosphoric acid, turns into fruit-siphosphate, which is sent further to the path of anaerobic oxidation. In the bumblebee, it is split into fructose-6-phosphate and phosphoric acid with heat release: F-6-F + ATP -\u003e - FDF + ADP; FDF -\u003e F-6-F + K3RO4.- F - heat that in the amount gives the ATP -\u003e - ADP -~ N3RO4.+ Heat. The fact is that, as opposed to other animals, the fruchozodiphospha-pelvis bumblebees does not oppress the products of the Splitting of ATP. As a result, the bumblebees reach the temperature difference between the muscles and the environment of about 8-20 ° C, which allows them to actively move and fade into cool weather, unfavorable for other insects.
In an emergency tool to changes in the temperature regime, hormones play an important role in a homoothermal role. Under conditions of low temperatures, an increased amount of adrenaline is ejected into the blood, which stimulates the mobilization of glucose and fatty acids and the intensity of oxidative processes. In the blood, the release of glucocorticoids is released from bonds with proteins, and then the new flow of them into the blood from the adrenal cortex. They increase the sensitivity of peripheral adrenoreceptors, reinforcing the effect of adrenaline. The activity of the thyroid gland is activated, whose hormones cause partial disagreement of breathing and phosphorylation in muscle and liver mitochondria, increasing heat generation. Under the action of high temperatures, the intensity of oxidative processes and heat generation is reduced, heat transfer increases. But all this is good for emergency, short-term adaptation of the body and it would be even harmful to it with a long change in temperature conditions. Indeed, if animals living in the field of low temperatures were protected from them, for example, only holo-dove shudder, it is unknown how they could lead an active life, to extract food, to escape from enemies, etc. So, with long adaptation to one or another temperature, adaptive mechanisms should be different: ensure the normal existence of the body under these conditions.
In order for a chemical reaction to occur, voltage or deformation and weakening of bonds in the molecules of reactants should occur. The energy required for this is called activation energy. An increase in temperature by 10 0 C increases the reaction rate by 2-3 times due to the increase in the number of activated molecules. When the temperature decreases, changes in reverse order are observed. If the body had strictly followed this law, then when changing the temperature of the medium, it would be in a very difficult position: low temperatures would slow down the metabolic reaction, which vital functions could not flow normally, and at high temperatures they would be overly accelerated. In fact, we see completely different. So, fish adapted to high and low temperaturesDifferences in the intensity of metabolism are not very high and quite commensurate. In other words, the reaction of metabolism in these species have different temperature optimi. For example, a raccoon dog intensity of metabolism is the lowest at 15 ° C, and in both directions it increases from this point. The temperature of the body in amplitude 35 0 C is preserved almost constant. And this means that the temperature conditions of the flow of metabolic reactions in this range are preserved optimal. When comparing two close species of animals, but inhabitants in different conditionsWe see that in the song the constancy of the intensity of metabolism and body temperature in the large range of medium temperatures is much better expressed than the fox. What is interesting: the intensity of metabolism under low ambient temperature It does not decrease, but persists at a constant level or increases, whereas, according to chemical laws, it should have been the opposite. Such an opportunity has opened before living organisms because all reactions of metabolism are enzymatic. And the essence of the action of enzymes is that they dramatically reduce the activation energy of reacting molecules. In addition, depending on the conditions of the medium, they can change the number of their properties: catalytic activity, the optimum temperature and acidity, the degree of affinity for the substrate. Therefore, the causes of the body's ability to "shy away" from chemical laws should be sought in changes in enzyme proteins.
These changes due to the adaptation to the temperature factor can go in three ways: to increase or decrease the number of molecules of this enzyme in the cell, change the set of enzymes in it, as well as the properties and activity of enzymes. The first way has its own reson. After all, any enzyme molecule at every current moment can interact with one substrate molecule. Therefore, the greater the enzyme molecules in the cell, the more significant the reaction products will be out, and the smaller it is, the lower and the output. This to some extent can compensate for the temperature decrease or increase in the intensity of metabolism. But this compensation is limited to the possibility of enzyme synthesis, and spatial considerations. Cell thosemay accommodate too many new macromolecules enzymes. Nevertheless, there are already firmly established data that, when adapting to cold, activity and maintenance of such essential aerobic oxidation enzymes as succinate dehydrogenase and cytochromic oxidase increase to cold.
There is no doubt that the second path defined by the repression of the synthesis of alone enzymes and the induction of the synthesis of others, in low temperatures, enzymes are highly synthesized, to a greater degree reduction in activation energy, and in high conditions less significantly affecting it. This applies primarily to isoenzymes. The enzyme lactatedehydro-genyase five isoforms. In this case, isoenzyme II4.more significantly reduces the activation energy than M 4. Therefore, when adapting to low temperatures, the first is more synthesized, and to the high - second. The enzyme of the nervous system of cholinesterase is two isoforms with different possibilities of reducing activation energy. The study of the brain of iris, adapter to different temperature conditions, showed that when adapting to a temperature of 2 0 C is solely iso-source I, to a temperature of 17 0 G - isoenzyme II, and in those living at 12 0 G - both isoforms. This also applies to seasonal changes: in winter, predominantly isoform I is synthesized, and in summer - isoform II.
The third way of adaptation is primarily a change in the affinity of the enzyme to the substrate. This is the basis of this - changes in the highest structures of enzyme proteins and properties of their active centers. In this case, the ability to associate their substrate, forming an enzyme-substrate complex, rises or decreases. Direct reasons for reasons are the change in the electrostatic properties of the active center, the degree of dissociation of atomic groups participating in the binding of the substrate, the ionic environment of the active center and the change in its spatial form. The shears of the temperature dependence of the activity of enzymes can be due to the addition to their molecules of various alto-solid effectors: proteins, phospholipids, inorganic ions, etc. In silver crucia, adapted for habitat at 5 and 25 ° C, investigated the activity of subcotion dehydrogenase, built into mitochondrial membrane and related with phospholipids. The enzyme was isolated in its pure form and freed from phospho lipids. At both groups, the structure was completely the same, and activity is lower than the maximum. Then phospholipids from the enzyme protein were added "Cold"And" thermal "mitochondria. The first activated the enzyme more than the second. The analysis of phospholipids showed that Coldmitochondria fatty acid phospholipids are most saturated. Perhaps that inthis is the reason for reducing the degree of resillection and phosphorus when adapting to cold and increase it when adapting to high temperatures.
Device to temperature conditions is not limited to changes in the field of enzyme systems, although they are the basis. When adapting to low temperatures in the muscles, the content of the CF increases, and in fatty depot - backup fat, which serves as a highly efficient source of energy and thermal insulator. In phospholipids of cell membranes, the content of unsaturated and polyunsaturated fatty acids increases, which prevents them with solidification at low temperatures. Finally, in animals capable of transferring very low temperatures, in the blood, tissue liquids and cells found biological antifreezes that prevent the freezing of intracellular water. For the first time they were allocated in Antarctic fish - not flow and Trematomas. By nature, they are glycoproteins, i.e. Compounds of sugar galactose with protein. Binding link is a nitrogen-containing base of acet l.ha Lactozam Ii. Their MM can reach 21 500, and for them is characterized by a high content of a rock-level-level guide that reduces the possibility of interaction between water molecules and ice formation. With lower temperatures, the body is encountered, the higher the antifreeze content. In summer it is less, in winter. Arctic insects, the role of antifreeze is performed by glycerin, also rich in hydroxyl groups. In the hemolyimph and tissues of these animals, the content of glycerin increases with a decrease temperatures.
The temperature of the caothelotermary changes after the ambient temperature. They are mainly ectotherm, the production and preservation of their own heat they have not enough to confront the thermal regime of habitats. In this regard, two main ways of adaptation are being implemented: specialization and tolerance.
Specialized types of stenothermna, they are adapted to life in such areas of the biosphere, where temperature fluctuations occur only in narrow limits. The way out of these limits is destroyed for them. For example, some unicellular algae., developing in mountain glaciers on the surface of the melting ice, die at temperatures exceeding + (3-5) ° C. Rain rainforest plants are not capable of carrying a decrease in temperature to + (5-8) ° C. Coral polyps live only in the range of water temperatures from +20.5 to +30 ° C, i.e. in tropical belt Ocean. ELPIDIA GLACIALIS Humancotus dwells at water temperature from 0 to +1 ° C and does not withstand deviations from this mode by any degree.
Another path of adaptation of pykilotermic species is the development of the stability of cells and tissues to a wide fluctuation of temperatures characteristic of most of the biosphere. This path is associated with periodic braking of metabolism and the transition of organisms into the latent state, when the temperature of the medium is strongly deviated from the optimum.
Effective Development Temperatures Pyacilline Organisms. The dependence of the growth rates and development from external temperatures makes it possible to calculate passage life cycle species in specific conditions. After cold depression, the normal metabolism is restored for each species at a certain temperature called temperature threshold of development, or biological zero development. Than more Temperature The medium exceeds the threshold, the more intensive development proceeds and, therefore, the sooner the passage of individual stages and the entire life cycle of the body is completed (Fig. 13).
Fig. 13. The condition of the headastrics developing at different temperatures after 3 days after fertilization of the egg (by S. A. Zernov, 1949)
To implement a genetic program of development, understand-kilometer organisms, it is necessary to obtain from the outside of a certain amount of heat. This heat is measured by the sum effective temperatures. Under effective temperature Understand the difference between the temperature of the medium and the temperature threshold of organisms. For each view, it has the upper limits, since too high temperatures are no longer stimulated, but the development is inhibited.
And the threshold of development, and the amount of effective temperatures for each view of their own. They depend on historical fitness to life conditions. For seeds of a moderate climate, such as pea, clover, a low development threshold: their germination begins at a soil temperature from 0 to +1 ° C; More southern cultures - corn and millet - begin to germinate only at + (8-10) ° C, and seeds palm tree To begin development, the soil warming up to +30 ° C.
The amount of efficient temperatures is calculated by the formula
X \u003d (t - c) · t,
where X. - the sum of effective temperatures; T. - ambient temperature, FROM - temperature of the development threshold and t. - The number of hours or days with a temperature greater than the threshold of development.
Knowing average temperature in any area, it is possible to calculate the appearance of a certain phase or the number of possible generation of the species of interest to us. Thus, in the climatic conditions of northern Ukraine, only one butterfly generation of the butterfly of apple-tree fruit can be performed, and in the south of Ukraine - up to three, which must be taken into account when developing measures for protecting gardens from pests. Duration of flowering plants depend on how the period they type the amount of necessary temperatures. For blooming mother-and-stepmother under Petersburg, for example, the amount of effective temperatures is 77, acids - 453, strawberries - 500, and yellow acacia - 700 ° C.
The amount of effective temperatures that need to be gained to complete the life cycle often limits the geographical distribution of species. For example, the northern border of forest vegetation approximately coincides with the July isotherms + (10-12) ° C. The north of the heat for the development of trees is not enough, and the forest zone is replaced by flavored tundra.
Calculations of efficient temperatures are needed in the practice of rural and forestry, when dealing with pests, introduction of new species, etc. They give the first, approximate framework for the preparation of forecasts. However, many other factors affect the distribution and development of organisms, therefore, in reality, temperature dependences are more complex.
Temperature compensation. A number of caototermic species living in conditions of variable temperatures develop the ability to maintain a more or less permanent level of metabolism in fairly wide limits of changing the body temperature. This phenomenon is called temperature compensation and is mainly due to biochemical adaptations. For example, mollusks on the coast of the Barents Sea, such as Littorina Littorea, and bivalve mussels (Mytilus Edulis), the intensity of the exchange, evaluated by oxygen consumption, is almost independent of the temperature in the years with which the mollusks are found daily during Tides and sings. In the spring-summer period, this range reaches more than 20 ° C (from +6 to +30 ° C), and cold water Their metabolism is just as intense as in warm air. This is ensured by the action of enzymes, which, with a decrease in temperature, change their configuration in such a way that they increase their affinity for the substrate and the reaction proceeds more actively.
Other methods of temperature compensation are associated with the replacement of acting enzymes similar to function, but working at a different temperature (from the isoenzymes). Such adaptations require time because it is inactivating some genes and the inclusion of others with the subsequent processes of the protein assembly. Similar acclimation (Temperature Optimum shift) underlies seasonal rearrangements, and also detected from representatives of widespread species in different climates of the area. For example, one of the types of bulls from Atlantic Ocean in low latitudes Q10 has a low value, and in cold northern waters. It increases at low temperatures and decreases with medium. The result of these compensations is that animals can maintain the relative constancy of activity, since even a slight increase in temperature in critical points enhances metabolic processes. Temperature compensation for each species is possible only in a specific temperature range, but not higher and not lower than this area.
Biochemical adaptations for all their effectiveness do not represent the main mechanism of opposition to unfavorable conditions. In fact, they are often "extreme means" and evolutionally produced in species only when other methods are impossible, physiological, morpho-anatomical or behavioral, avoid extreme effects without restructuring the main cell chemical. A number of caigious organisms have the capabilities of partial regulation of heat exchange, i.e., in some ways to increase the flow of heat into the body or take it out of excess. Basically, these adaptations occur in multicellular plants or animals and in each group have their own specifics.
Elements of temperature regulation in plants. Plants produce little metabolic heat due to the effective translation of the chemical energy from one forms to others, so endothermia cannot be used by them for thermoregulation. Being at organisms attached, they must exist with that thermal mode, which is created in the places of their growing. However, the coincidence of the body temperatures of the plant and the medium is more likely to consider an exception than the rule, due to the difference in the speed of receipt and heat of heat. Higher plants are moderately cold and moderately warm euritemen belts. The thermal regime of plants is very volatile. The temperature of different organs is different depending on their location relative to the incident rays and differ in the degree of heating layers of air (Fig. 14). The heat of the soil surface and the surface layer of air is especially important for the tundra and high-mountain plants. Spleency, solar and pillow-shaped forms of growth, the pressing of the leaves of the sockets and local-overbearing shoots to the substrate for arctic and alpine plants can be considered as an adaptation to better use Heat in conditions where it is not enough (Fig. 15).
Fig. fourteen. Temperature (in ° C) of different organs of plants (from V. Larhera, 1978).
As part of the air temperature at the height of the plant:
A - plant tundra Novosieversia Glacialis,
B - Cactus Ferocactus Wislisenii
Fig. fifteen. Alpine Schilldag Plant Kachym Pangles - Gypsophila Aretiodes (by K. P. Popov, E. M. Seifulina, 1994)
In the days with variable cloudiness, the above-ground organs of plants are experiencing sharp temperature differences. For example, at a pioneering ephemeroid of Siberian, when the clouds close the sun, the temperature of the leaves may fall from + (25-27) ° C to + (10-15) ° C, and then when the plants are again illuminated by the Sun, rises to the previous level. IN cloudy weather The temperature of the leaves and flowers is close to the ambient air temperature, but is more often a few degrees below due to transpiration. Many plants have a difference in temperatures noticeable even within one sheet. Typically, the top and edges of the leaves are colder, so during night-cooled in these places, the dew is first condensed and another is formed. When heated sunny rays Plant temperature can be significantly higher ambient temperature. Sometimes this difference reaches more than 20 ° C, as, for example, in large fleshy stems of desert cacti or stems of single standing trees.
The main means of overturning excess heat and prevent burns - ustovic transpiration. The evaporation of 1 g of water is derived from the body of a plant about 583 feces (2438 J). If in hot sunny weather Lubricate this surface of the leaf, on which the Ustian is located, the sheet is very quickly dying from overheating and burns. Strengthening of transpiration when increasing the temperature of the medium cools the plant. However, this mechanism of thermoregulation is effective only in conditions of sufficient water supply, which rarely happens in arid areas.
Plants also have near morphological adaptation aimed at preventing overheating. This serves a thick oxtress of leaves, scattering part of the sun's rays, a glossy surface that contributes to their reflection, a decrease in the absorbing rays of the surface. Many cereals, like, for example, a hitch or oatmeal, in the heat rolling the sheet plates into the tube, the eucalyptus leaves are located the edge to the sunshine, from part of the plant arid areas of the foliage completely or partially reduced (saxauls, cacti, cacti-shaped milk, etc.).
In extremely cold conditions, some are also served by some morphological features Plants. The main ones are special forms of growth. Dwarf and the formation of sharpening forms allows the use of an overground layer microclimate in the summer and be protected in the winter. Peculiar plants pillows. Their hemispherical form is created due to dense branching and weak shoots. The leaves are located only on the periphery, as a result of which the overall surface of the plant is saved, through which heat dissipation occurs. As is known, from all geometric shapes in the ball the smallest surface ratio to the volume, which is implemented in the form of a plant. A significant part of cold-resistant plants has a dark color, which helps to absorb the heat rays and heat even under the snow. In Antarctica, the temperature of dark brown lichens is above 0 ° C, even under a layer of snow in 30 cm.
AND transpiration and morphological adaptation Aimed at maintaining thermal Balance Plants obey physical laws nature and relate to ways physical thermoregulation. In plants, physical thermoregulation is also represented by various elements, but in general, its efficiency is low and distributed only a few percent of the total heat flux through the organisms. These elements of thermoregulation allow plants to survive under conditions when the temperature of the medium approaches the main critical values, but cannot stabilize their common thermal balance. More essential value for plants have physiological mechanisms temperature adaptation, Enhance their tolerance to cold or overheating (accumulation of antifreeze cells, leaf falling, dieting overhead parts, decrease in water cells etc.).
In different phases ontogenesis, heat requirements are different. IN moderate belt Seed germination occurs usually at lower temperatures than bloom, and a higher temperature is required for flowering than for ripening fruits.
According to the degree of plants adaptation, three groups can be distinguished for the conditions of the state of the heat deficit:
1) non-odorous plants - badly damaged or dying at temperatures that are not yet achieving water freezing points. The death is associated with the inactivation of enzymes, a violation of the exchange of nucleic acids and proteins, the permeability of membranes and the cessation of the current of assimilates. These are plants of rain tropical forests, algae of warm seas;
2) nevoraro-resistant plants - tolerate low temperatures, but die as the ice begins to form in the tissues. At the occurrence of the cold season, they increase the concentration of osmotically active substances In cellular juice and cytoplasm, which lowers the freezing point to - (5-7) ° C. Water in cells can be cooled below the freezing point without immediate ice formation. The supercourse state is unstable and lasts most often a few hours, which, however, allows plants to carry freezing. Such are some evergreens subtropical plants - Lavra, lemons, etc.;
3) ice-resistant or frost-resistant, plants - grow in areas with seasonal climate, with cold winters. During severe frosts, the above-ground organs of trees and shrubs are freezed, but nevertheless preserve viability, as in cells crystalline ice Not formed. Plants are prepared for the transfer of frosts gradually, passing the pre-hardening after growth processes end. The hardening is accumulated in sugars cells (up to 20-30%), derivatives of carbohydrates, some amino acids and other protective substances that bind water. In this case, the frost resistance of the cells increases, since related Water It is more difficult to delay the ice crystals formed in extracellular spaces.
Thaw in the middle, and especially at the end of winter cause a rapid decrease in plant resistance to frosts. After the end of the winter rest, the hardening is lost. Spring frosts that have come suddenly can damage the shooting on the growth of shoots and especially flowers even in frost-resistant plants.
By degree of adaptation to high temperatures, the following groups of plants can be distinguished:
1) nezarostiy plants already damaged at + (30-40) ° C (eukaryotic algae, water flowering, ground mesophytes);
2) tablery plants Pull with half-hour heating to + (50-60) ° C (plants of dry habitats with strong insolation - steppes, deserts, savannah, dry subtropics, etc.).
Some plants regularly experience the effects of fires when the temperature briefly rises to hundreds of degrees. Fires are especially frequent in savannah, in dry tone forests and shrub thickets of Chaparral type. There is allocated a group of plants -Pirofitis, Fire-resistant. In the trees of savannah on the trunks of thick crust, impregnated with refractory substances, reliably protecting internal fabrics. The fruits and seeds of pyrophyetites have thick, often gloves that are cracking, being laid fire.
The possibilities of regulation of temperature in pokylotermic animals. The most important feature of animals is their mobility, the ability to move in space creates fundamentally new adaptive capabilities, including in thermoregulation. Animals are actively choosing habitat with more favorable conditions.
Unlike plants, animals with muscles produce much more from their own, internal heat. When cutting muscles is released significantly more thermal energy than in the functioning of any other organs and tissues, since the efficiency of the use of chemical energy to make muscle work relatively low. The more powerful and more active the muscles, the more heat can generate an animal. Compared to plants, animals have more diverse capabilities to regulate, constantly or temporarily, the temperature of its own body.
Poikilotermic animals remain, however, as plants, ectotherm, since the overall level of their metabolism is not so high so that the inner heat is enough to heal the body. For example, at a temperature of +37 ° C, the desert iguana consumes oxygen to 7 times less than rodents of the same value. Nevertheless, some of the caustic animals are able to maintain the body temperature higher than in the environment. For example, concrete butterflies, the leading night lifestyle, fly and feed on the flowers even at +10 ° C. During the flight, the temperature of the chest department is maintained at 40-41 ° C. Other insects can fly in cold air, pre-warmed their aircraft muscle for take-off, for example: locust, bumblebees, wasps, bees, large night scoops and other bumblebees collect nectar even at +5 ° C, having body temperature 36-38 ° C . With the cessation of activity, insects are quickly cooling. Generate heat for heating can in some cases and reptiles. The python female, which wrapping the masonry, reducing muscles, is capable of increasing the temperature by 5-6 ° C in the range of external temperatures from +25 to +33 ° C. At the same time, the consumption of oxygen it increases by almost 10 times before the limit for the reptile level. In the cooler air, the snake becomes sluggish and inactive.
Basic ways to regulate body temperature in Pykilotermic animals - behantic: Change posture, active search for favorable habitats, a number of specialized forms of behavior aimed at creating a microclimate (digging holes, the construction of nests, etc.).
A variable of poses Animal can enhance or weaken heating due to solar radiation. For example, a desert locust in the cool morning clock substitutes the solar rays a wide side surface of the body, and at noon - a narrow dorsal. Lizards Even high in the mountains during normal activity can maintain body temperature, using the heating of straight solar rays and heat heated rocks. According to research in the Caucasus, at an altitude of 4100 m, the body temperature of Lacerta Agilis at times at 29 ° C exceeded the air temperature, keeping at 32-36 ° C. In severe heat, animals are hidden in the shadow, hide in nonorah, cream, etc. In the deserts during the day, for example, some types of lizards and snakes are climbing the bushes or break into less heated layers of sand, avoiding contact with a hot surface of the soil. Lizards, if necessary, rapidly move hot surfaces only on the hind legs, thereby reducing contact with the soil (Fig. 16). By winter, many animals are looking for asylum where temperatures move more smoothed compared to open habitats. Even more complex forms of the behavior of public insects: bees, ants, termites that build nests with a well-adjustable temperature inside them, almost constant during their activity.
Fig. sixteen. The behavior of lizards saving from the hot sand surface in the desert
Fig. 17. Evaporative thermoregulation in animals:
1 - Lizard - evaporation from the mucous membranes with the open mouth;
2 - Antelope Suslik - rubbing saliva;
3 - Coyote - evaporation from the mucous membranes during rapid breathing
A number of caothelotermic animals effectively operates and mechanism evaporative thermoregulation. A frog in an hour at +20 ° C loses on land 7770 J, which is 300 times more of its own heat product. Many reptiles when the temperature approaches the top critical is starting to breathe hard or keep the mouth open, reinforcing the return of water from the mucous membranes (Fig. 17). Bees flying in hot weather avoid overheating, highlighting a drop of liquid, the evaporation of which removes excess heat.
However, despite a number of possibilities of physical and behavioral thermostat, caustic cells can only carry out in a narrow temperature range. Because of the common low level Metabolism They cannot provide the constancy of the thermal balance and are quite active only close to the upper temperature limits of existence. Mastering habitats with constantly low temperatures for cold-blooded animals is difficult. It is possible only in development. specialized Cryophilia And in the ground conditions is available only to small forms that can use the slightest advantages of the microclimate.
P. 133. Remember.
1. What is the habitat?
The habitat is part of nature surrounding living organisms and has a direct or indirect impact on them.
2. What factors refer to the factors of inanimate nature?
In the process historical Development Organisms adapt to a specific complex abiotic factorswhich become mandatory conditions for their existence. At the same time, in the process of livelihoods, organisms themselves are involved in the formation of a abiotic (inanimate) environment. During photosynthesis, plants absorb carbon dioxide And oxygen is distinguished into the atmosphere, animal filtrators purify water, green plantings prevent soil erosion, and plants from the legume family enrich the soil with nitrogen - such examples can be given a variety.
P. 136 - 137. Questions for repetition and task.
1. What adaptations to ambient temperature changes exist in plants and animals?
The temperature differences of the resting stage of organisms are well withstanding - cysts, insect dolls, plant seeds. Some bacteria disputes are able to transfer temperature fluctuations from -273 to +140 ° C. Hercharmal animals - birds and mammals - maintain a constant body temperature with high level metabolism, perfect thermoregulation and good thermal insulation. For example, some cetacean and lastonous, due to the presence of a thick layer of subcutaneous fat, live in the northern seas, where the water temperature is constantly about 0 ° C. For the winter, many mammals grow more dense fur, some of them (for example, crops) flow into hibernation. The birds increase the mass of feathers, many species migrate to warmer zones. Capable organisms to protect themselves and from increased temperatures. In the afternoon in the desert, the temperature exceeds 60 ° C, so many animals are hidden in nonorah and go to the surface only at night. In the heat of the plant increase evaporation from the surface of the leaves. Many mammals of overheating protection serves as active sweat selection. The most impressive example of adaptation to high temperatures is algae and hot-source bacteria, where the water temperature exceeds 70 ° C. Due to the special structure of their proteins are able to resist denaturation.
2. Tell us about the adaptations of living organisms to the lack of water.
Water is the necessary component of the cell, so its quantity in one or another habitat determines the nature of vegetation and the animal world in this area. Some depending on the amount of water in the environment, it is also the content of it in the body of plants and animals and their resistance to drying.
Drought-resistant plants (spindle camel, saksul, desert wormwood) have a very long, depth of 10 or more root system. Their leaves are usually narrow and rigid, with a wax flare on the surface, which reduces water loss during evaporation. Some plants (cacti, mopokhodi) forms a thick stem with a well developed photosynthetic and water-based cloth, and the leaves turn into spines or scales. A row of herbs time to grow and fonds for the wet spring period, and then he experiences drought in a state of seeds, bulbs, tubers. On a hot day, the leaves of some plants can be rotated to the incident rays of the sun "edge", for example, as it occurs at wild lettuce (negative heliotropism). Eucalyptus to reduce transpiration also turns the leaves to the sun to the sun. Such orientation of the plates protects the body from excessive water loss and overheating. Many animals are also well adapted to reduced humidity conditions. Some of them never drink using metabolic water and food from food. Artogih protects against evaporation dense chitinic shell, and reptiles - oroging covers, lost skin glands. The product of allocations in many animals is almost anhydrous uric acid. There are many behavioral adaptation: Night lifestyle, hibernation in a dry period, etc.
3. Due to which part of the spectrum of solar radiation in plants is carried out photosynthesis?
For the implementation of photosynthesis of plants use visible part spectrum. At the same time algae and higher plantsWith green photosensitive pigment (chlorophyll), more efficiently use extreme spectrum sections - red-orange and blue-purple. The green color of the leaves is due to the fact that it is this component of solar radiation chlorophyll absorbs weaker (and therefore reflects more). Brown and red algae with several other photosensitive pigments are mainly adjusted to the blue-green part of the spectrum.
4. Tell us what you know about biological rhythms of living organisms.
The behavioral and physiological activity of very many organisms is characterized by rhythm: breathing and heartbeat, activity, synchronous with tides and lowers (i.e. with the phases of the moon), etc. The most common factor defining biological rhythms is the illumination that changes during the day and seasonally. Plants and animals react to the ratio between the duration of the lighting period and darkness during the day or the season. This phenomenon is called photoperiodism. Photoperiodism adjusts the daily and seasonal rhythms of the life of organisms, and is also a climatic factor that determines the life cycles of many species. In plants, photoperiodesism is manifested in synchronization of the flowering period and ripening of fruits with the period of the most active photosynthesis; In animals - in the coincidence of the reproduction period with an abundance of food, in migrations of birds, changing the woolly cover in mammals, shipping in hibernation, changes in behavior, etc. Many flowers open and closed at a certain time; Animals also organize their daily routine depending on the illumination (day or night activity). Whole line biochemical and physiological processes in the human body varies with a rhythm of 24 hours (sleep and wakefulness, body temperature, arterial pressure, highlighting hormones). For seasonal rhythms, the length of the daylight is defining. It depends on it the dates of flowering and ripening of fruits, as well as the beginning of the leaf fall on plants, the migration of birds, the change of the woolly cover in mammals, the beginning of the marriage season, preparation for hibernation, etc.
Think and execute.
1. What climatic conditions And soil is characteristic of your region?
The climate of the Urals moves from moderately continental to the continental. Continentality increases when driving from west to east and from north to south. The huge length of the Urals from the north to the south is manifested in the zonal change of the types of its climate (the northern and southern regions have different circulation and radiation modes). North lies in Subarctic; South - in the central arid areas. Contrasts between the north and south are intensified in the summer. average temperature July in the north of 60s - 80s, in the south - 220s; 240c. In winter, temperature contrasts are smoothed -220c; -200c in the north; -150c in the south. The Urals crosses the following soil and vegetable areas: Tundra, Forestandra, Forest, Forest Safety, Steppe, semi-deserted. The zonality here is a mining and latitudinal (distinguished by the displacement of the soil and vegetable zones to the south). In the foothills, the barrier role of the Urals (in the Southern Urals instead of the steppe and southerly-satellite landscapes are common and semeshots). Mountain soil Urals of all types have common features: 1. They do not have continuous distribution, but are interrupted by rocky protrusions and kurumami; 2. Have a shortened profile and greater saturation of the chip. There are significant differences in soil cover when driving from west to east (composition of rocks).
2. What do you think, with a constant directional change in abiotic environmental conditions, the adaptation of living organisms to these changes can not be infinite?
Abioticheskaya - knows for life for life, a with you to behave our reasons, surrounding the conditions can be changed, and the adaptation to them will shut.
3. Why do additional artificial lighting, increasing the length of the daylight apply on poultry farms and in the greenhouse?
An additional artificial lighting is used on the poultry farms to increase product performance. Bird living in natural conditions, very sensitive to seasonal changes Environment. In the autumn and winter, the light period is rather short, because of which the chickens are almost stopped rushing. They are deceived so that they give more eggs, artificially increasing the length of the daylight.
Temperature adaptation of plants
The functional activity of living biological systems significantly depends on the temperature level of the environment. First of all, it concerns organisms that are not able to maintain a constant body temperature (all plants and many animals). It is in such organisms (pallotermic) to increase the temperature to a certain limit significantly accelerates physiological processes: growth rates and development (in insects, reptiles), germination of seeds, growth of leaves and shoots, bloom, etc.
Excessive temperature increase causes the death of organisms due to thermal denaturation of protein molecules, irreversible changes in the structure of biological colloid cells, violations of enzymes, sharp increase in hydrolytic processes, respiration, etc. On the other hand, a noticeable decrease in temperature below about ° C may cause cell death and the entire body .
IN natural conditions The temperature is very rarely held at a level favorable for life. The answer to this is the emergence of special devices in plants and animal, which weaken the harmful effects of temperature fluctuations. This, in particular, the complex of properties and adaptive devices that form the appropriate level of winter hardiness and frost-resistant plants.
- Winter hardiness - plant resistance to the complex of adverse factors of the winter period (alternation of frost and thaws, ice crusts, linkers, spray, etc.). It is determined and ensured by the transition of plants into the state of organic peace, the placement of the kidneys in protected places, the accumulation of energy material (starch, fats), discharge of leaves, adaptive reactions of organisms.
- Frost resistance - The ability of cells, tissues and whole plants without damage to carry the effect of frosts. Due to many physiological biochemical devices and properties in frost-resistant plants, ice formation occurs at a lower temperature than less frost-resistant, and is accompanied by smaller damage.
- Cool resistance - The property of early plants (ephemers and ephemeraids) successfully grown at low positive temperatures. This term is also used to characterize thermal-loving plants (corn, cucumbers, watermelons).
Winter and frost resistance is characteristic of plants only in the winter when they managed to harm and go to rest state. In the period of vegetation (in summer), all plants are not able to withstand even the short-term impact of small frosts.
- Hardening of plants - Formation in plants The ability to successfully withstand unfavorable conditions under the influence of the specific conditions of the autumn season. Has a two-phase character. During the first, carbohydrate accumulation occurs, the redistribution of nutrients between the organs, which contributes relatively warm and sunny weather. In the second phase, with a gradual decrease in temperature, the amount of osmotically active substances in vacuoles increases, the amount of water decreases, the state of the cytoplasm - the plants are changed to the rest state.
- Condition of rest - A qualitatively new stage of the plant organism, which is moving the winter plants with the onset of unfavorable conditions. It is characterized by the cessation of visible growth and minimizing the life, dieting and the dejunation of the leaves and the above-ground organs of grassy perennials, the formation of the scales on the kidneys, the thick layer of the cuticle and the cortex on the stems. Inhibitors are accumulated in tissues and cells that inhibit growth and formation processes, which makes plants incapable of germination even in the most favorable artificially created conditions, as well as during random autumn and wounds of unemplated warming.
The period (state) of deep, or organic peace, due to the corresponding preparation and internal rhythm of the development of the plant organism, and the period of forced rest, in which plants are abide of the deep peace, when their growth is forced to restrain the unfavorable conditions - low temperature, disadvantage of nutrients. Forced peace is easy to interrupt, creating a plant favorable conditions.
From the state of deep peace, the plants are difficult, since the duration of its majority of them is significant - until the end of January - February. The output of plants from this state is possible only after its end and accomplishment in the body of the corresponding biochemical and physiological transformations caused by the influence of the period of minus temperatures of a certain duration. After the end of the rest period in plants, the number of nucleic acids significantly increases, growth inhibitors disappear and auxins appear - stimulants of growth processes.
The ability to move into a state of rest is the necessary stage of ontogenesis of plants, internally due to the rhythmicity of physiological and biochemical processes. This property occurred in plants in the process of evolution as an adaptive response in response to periodic changes in the temperature conditions of the external environment.
Many plants go to the state of rest not only in winter, but in the summer. This is an early blooming plants (tulips, crocuses, proleski). A large number of plants of tropical areas, deserts and semi-deserts also goes into a state of summer peace. The state of resting of different duration is characteristic of freshly coloned seeds and fruits, tubers, bulbs, rooteplood.
There are methods and techniques with which it is possible to derive plants from the state of deep peace. These are warm baths (37-39 ° C), processing of ether couples, pumping the base of the renal needle, etc.
The thermal changes in the habitat of organisms are not only negative, but also a positive effect. Many species of plants to go to flowering and fully complete their life cycle, need a period of low temperatures usually small duration at a certain stage of ontogenesis. Examples of the stimulative action of low temperatures are:
- The process of narrowing is the transition of sprouted seeds of winter crops with cold effects in the state of development (the formation of reproductive organs).
- Stratification - Impact on low temperature seeds stored under certain conditions in order to prepare them for germination. In vivo, the preparation of seeds with solid shells to germination is carried out in the Cine-Winter period, i.e., with the mandatory effect on them, the periods of low and minus temperatures.
- The formation of flowering arrows with germinating bulbs is possible only in the case of pre-lying at low temperatures.
- A decrease in temperature in combination with other factors initiates the transition of perennial plants into a state of organic rest, which is most effectively for successful transfer of the totality of adverse winter factors.
The rate of passage of the stages of the life cycle of plants and animals, their growth and development substantially depend on temperature. Thus, the normal metabolism in plants and caothelotermic animals after cold oppression (winter hibernation, rest period) is restored at a temperature determined for each type, which is called the temperature threshold of development. The more the temperature of the medium exceeds the threshold, the more intense the development of the body proceeds. To estimate the amount of heat produced by the plant to complete the growing period or passing the life cycle of animals from eggs or eggs to adult individualUse an indicator of the amount of effective temperatures (σt) obtained by summing up daily exceeds average daily temperature The air of a certain amount of it corresponding to the temperature threshold of development.
The threshold temperature of the vegetation of the vegetation of most of the vegetation representatives of the moderate zone is considered to achieve the average daily temperature of 5 ° C, for cultivated plants - 10 ° C, for thermal-loving - 15 ° C, for the larvae of most animals - about ° C.
From sowing to ripening seeds, different plants require different amounts of effective temperatures, the value of which can noticeably change from the climate situation and the biological properties of the body (Tab):
Temperature adaptation of animals
Compared to plants, animals have more diverse capabilities to regulate body temperature, namely:
- by chemical thermoregulation - an active change in the magnitude of heat-product by increasing metabolism;
- by physical thermoregulation - a change in the level of heat transfer based on the development of heat-shielding cover, special devices of a crown system, the distribution of fat stocks, especially in the brown tissue, etc.
In addition, some features of animal behavior also protect their existence in changeable environment environments: the choice of space with favorable microclimatic conditions - breaking into the sand, in mink, under stones (animals of hot steppes and deserts), activity during a certain period of day (snakes, tushkars, Susliki), construction of storage facilities, nests, etc.
One of the most important progressive devices is the ability to thermoregulation of the body in mammals and birds, their warm-bloodedness. Due to this environmentally friendly adaptation, higher animals are relatively independent of the temperature conditions of the medium.
The ratio of the surface of the body to its volume is important for maintaining the temperature balance, since the amount of heat generated depends on the body weight, and the heat exchange is carried out through the covers.
The connection between the size and proportions of the body of animals with temperature-climatic conditions indicates the Bergman rule, according to which of two close types of warm-blooded, characterized by dimensions, larger living in a colder climate, as well as the allepa rule, for which many mammals and birds northern Hemisphere The relative dimensions of the limbs and other protruding parts (ears, beaks, tailings) are increased to the south and decrease to the north (to reduce heat transfer in the cold climate).
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