A violation of the body's thermoregulation or a disorder of the constancy of body temperature is provoked by dysfunction of the central nervous system. In case of violation of thermoregulation processes, two types of reactions are possible. If the body temperature rises, peripheral vessels dilate, sweating begins. If the temperature, on the contrary, decreases, the blood vessels narrow, the muscles contract, the limbs get cold, and tremors appear.
Higher animals possessing the property of constant body temperature have a system for maintaining temperature in equilibrium. Thermoregulation balances heat production and heat release. There are two main types of thermoregulation: chemical (its main mechanism is increased heat generation during muscle contractions - muscle tremors) and physical (increased heat exchange due to the evaporation of fluid from the body surface during perspiration). In addition, the intensity of metabolic processes and the narrowing or expansion of skin vessels are of a certain importance for heat production and heat transfer.
The thermoregulatory center is located in the brain stem. In addition, hormones of the endocrine glands, in particular, play a role in thermoregulation. The violation of body thermoregulation associated with a decrease in temperature is called hypothermia. The violation of thermoregulation of the body in humans associated with an increase in temperature is called hyperthermia.
Violation of thermoregulation processes: hyperthermia
Hyperthermia (overheating) occurs when the mechanisms of thermoregulation are disturbed, in which heat production prevails over heat transfer. Body temperature can reach 43 ° C or more.
Most frequent reasons such a violation of human thermoregulation is an increase in the temperature of the external environment and the appearance of factors that impede adequate heat transfer (for example, excessively warm clothing, high humidity, etc.).
When this type of thermoregulation disorders appears, adaptation mechanisms are activated: behavioral reactions with the help of which a person tries to avoid exposure to excessive heat (for example, turns on a fan), an increase in heat transfer mechanisms, a decrease in heat production and a stress reaction. In accordance with the results of the interaction of hyperthermia and adaptation processes, the stage of compensation and the stage of decompensation of hyperthermia are distinguished.
In the stage of compensation, there is an expansion of the arterial vessels of the skin and the associated increase in heat transfer. With a further increase in temperature, heat transfer begins to occur mainly only due to perspiration.
In the stage of decompensation, there is a violation of adaptation mechanisms, sweating decreases significantly, body temperature can rise to 41-43 ° C. There is a violation of the functions and structures of cells in connection with the direct damaging effects of high temperature, which leads to severe dysfunctions of systems and organs, primarily the central nervous system and the cardiovascular system.
Heatstroke is a variant of hyperthermia, in which adaptation mechanisms are rapidly depleted. This can occur both at a high intensity of the thermal factor and as a result of a low efficiency of the adaptation mechanisms of a particular organism. Symptoms of such a violation of thermoregulation are the same as in the stage of decompensation of hyperthermia in general, but more severe and growing much faster, in connection with which heatstroke is accompanied by high mortality. The leading mechanisms of the pathogenesis of changes in the body correspond to those in hyperthermia in general. But with such a violation of thermoregulation of the human body, particular importance is attached to intoxication, acute heart failure, respiratory arrest, edema and hemorrhages in the brain.
Sunstroke - This is one of the forms of hyperthermia. It occurs due to the direct effect of the heat of the sun's rays on the body. With such a pathology of thermoregulation, the above mechanisms of hyperthermia are activated, but the leading one is brain damage.
Thermoregulation pathology of the body: fever
Fever should be distinguished from hyperthermia. Fever - this is the body's reaction to irritants of an infectious and non-infectious nature, characterized by an increase in body temperature. In fever (as opposed to hyperthermia), the balance between heat production and heat transfer is maintained, but at a higher than usual level.
The reason for this violation of thermoregulation is the appearance in the body of pyrogenic substances (pyrogens). They are subdivided into exogenous (waste products of bacteria) and endogenous (breakdown products of damaged cells, altered serum proteins, etc.).
There are the following stages of such a pathology of human thermoregulation:
- temperature rise stage;
- the stage of temperature standing at a higher level than normal;
- temperature reduction stage.
Fever up to 38 ° С is called subfebrile, up to 39 ° С moderate, or febrile, up to 41 ° С - high, or pyretic, over 41 ° С - excessive, or hyperpyretic.
The types of temperature curves (graphs of daily temperature fluctuations) can be of diagnostic value, since they often differ significantly in various diseases.
Persistent fever is characterized by daily temperature fluctuations of no more than 1 ° C. With laxative fever, the difference between morning and evening temperatures is 1-2 ° C, and with exhausting (hectic) - 3-5 ° C. Intermittent fever is characterized by large ranges of morning and evening temperatures with periodic normalization. Recurrent fever combines periods of several days in which the temperature is normal and periods elevated temperaturewhich alternate one after another. With perverted fever, the morning temperature exceeds the evening temperature, and atypical fever does not have any patterns at all.
With a sharp decrease in temperature, they speak of a critical decrease, or a crisis (this may be accompanied by a pronounced decrease - a collapse); its gradual decrease is called lytic, or lysis.
A number of changes occur in systems and organs with fever.
So, in the central nervous system with fever, the phenomenon of oppression is observed. A concomitant symptom of such a violation of the body's thermoregulation is tachycardia, about 8-10 beats per minute for each degree of rise (however, in some diseases, for example, there may be bradycardia, which is associated with the depressing effect of a bacterial toxin on the heart). At the height of the fever, breathing may be rapid.
Fever, however, also has a positive effect. So, with a fever, the reproduction of some viruses is inhibited, the vital processes and division of many bacteria are suppressed, the intensity of immune reactions increases, the growth of tumors is inhibited, and the body's resistance to infections increases.
With similar symptoms, the causes of these violations of the body's thermoregulation are different. Fever is caused by pyrogens, and hyperthermia is caused by high ambient temperatures.
With such a pathology as fever, the mechanisms of thermoregulation continue to operate (the balance between heat production and heat transfer is shifted to a higher level), with hyperthermia, the mechanisms of thermoregulation are disrupted.
Fever is the body's reaction to certain external and internal influences with certain positive qualities, hyperthermia is, of course, a pathological process that is harmful to the body.
Impaired body thermoregulation: hypothermia
Hypothermia is a condition characterized by a decrease in body temperature below normal.
The leading reason for such a violation of the body's thermoregulation is a decrease in the ambient temperature. In addition, hypothermia against the background of a slight decrease in external temperature leads to disturbances in the mechanisms of heat generation: extensive muscle paralysis, a violation of heat production due to a decrease in metabolic intensity with reduced production of adrenal hormones (including damage to the hypothalamic-pituitary region), as well as an extreme degree of exhaustion. The following factors can also contribute to hypothermia: high air humidity, wet clothes, immersion in cold water, wind (which enhances heat transfer); in addition, starvation, overwork, alcohol intoxication, trauma and illness lead to a decrease in the body's resistance to hypothermia. The consequences of a violation of thermoregulation can be general hypothermia and local cold injury - frostbite.
According to the time of death, acute (within an hour), subacute (within 4 hours), slow (over 4 hours) hypothermia are distinguished.
As with hyperthermia, the development of hypothermia is subdivided into the stage of compensation and the stage of decompensation.
The stage of compensation is characterized by behavioral reactions (a person tries to warm up), a decrease in heat transfer (skin vessels narrow, sweating stops), an increase in heat production (blood pressure and heart rate increase, blood flow in internal organs and the intensity of metabolic processes in organs and tissues increase, muscle tremor appears). The body temperature decreases slightly.
If the cold continues to act, and the adaptation mechanisms cannot cope with its pathogenic effect, then the stage of decompensation begins. There is a breakdown of the thermoregulation system, suppression of the centers of regulation of the brain, which leads to a drop in cardiac activity, a weakening of the intensity of respiration, hypoxia and acidosis, a disorder of the functions of organs and tissues, as well as microcirculation. The consequence of this is a violation of the exchange of water and electrolytes and the appearance of cerebral edema. Death occurs due to the cessation of blood circulation and respiration due to the increasing suppression of the regulatory centers of the central nervous system.
Frostbite usually affects areas of the body that are not protected or poorly protected by clothing (nose, ears, fingers and toes). In response to the effects of cold, there are such signs of a violation of thermoregulation as spasm of skin vessels, followed by their expansion and arterial hyperemia; with continued exposure to cold, secondary vasospasm may occur, which leads to tissue ischemia and damage to them up to necrosis of the skin and deeper tissues.
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Fever is a defensive-adaptive reaction developed in the process of evolution, which develops as a result of exposure to the body of pyrogenic agents and consists in establishing its heat balance at a new, higher level.
The term febris (fever, fever) has been known in medicine since ancient times. Since the overwhelming majority of infectious diseases (in the ancient period and in the Middle Ages it was the leading pathology of mankind) was accompanied by a vivid picture of a feverish state (chills, fever, confusion of consciousness), fever has long been considered as a kind of typical reaction, but for a long time it was rather a nosological concept. , that is, it had the "status" of an independent disease ("febrile illness", "swamp fever", "forest fever", etc.). Traditionally, this trend has continued to this day: as independent nosological forms, for example, have been identified. "Yellow fever", "Q fever", "rocky mountain fever", etc.
However, gradually in the medical world, the concept of fever as a symptom complex typical for many diseases of various etiologies (both infectious and non-infectious) began to be established. In this case, the main, leading symptom of fever was and remains overheating of the patient's body, the accumulation of heat in it. With the development of ideas about the physiological mechanisms of thermoregulation in homeothermic organisms, the first theories of the pathogenesis of febrile states appeared. So, back in the sixties of the XIX century, the idea arose that fever is the result of a significant increase in heat production in the human body in the absence of a level of heat transfer balanced with this process. At the same time, it was revealed that an increase in the body temperature of a febrile patient does not have a significant dependence on the ambient temperature. So it was established a radical difference between fever and hyperthermia. At the same time, it was suggested that "fever" (pyrogenic) substances cause fever due to their effect on the thermoregulatory centers located in the brain. Numerous studies of this common and characteristic symptom for a variety of diseases have made it possible at the present time to create a fairly clear theory of the onset and development of fever.
An increase in body temperature and the transition of the thermoregulation system to a new, higher level of functioning occurs as a result of exposure to the body of biologically active substances - pyrogens.
Pyrogens are classified into exo- and endogenous.
Exogenous pyrogens enter the body from the outside, while endogenous ones are formed in the body itself either during the decay of dying tissues, or are the result of the interaction of exogenous factors with certain cells of the body.
Microbiological and biochemical studies have made it possible to identify a number of both exo- and endogenous pyrogens. Thus, pyrogens were isolated from the cell membranes of some microbes by high purification, which in their own way chemical composition turned out to be polysaccharides or lipopolysaccharides (pyrogenal, pyrogen, pyrexal, etc.). It was also found that some protein substances in the microbial cell also have a pyrogenic effect. Purified exogenous (microbial) pyrogens (poly- and lipopolysaccharides) are thermostable, non-toxic, have no antigenic properties.
Endogenous pyrogens are formed in the body in the process of phagocytosis of microbial cells, as well as tissues damaged by neutrophilic leukocytes and other phagocytic cells. Endogenous pyrogens, of which the leukocyte pyrogen is the best known, are thermolabile.
The general scheme of the effect of pyrogenic substances on the body is as follows. When exogenous pyrogens enter the internal environment of the body, as a result of their phagocytosis, endogenous pyrogens are formed, most of which are of a protein nature. Endogenous pyrogens can persist for a long time in the internal environment of the body. It is their effect on the centers of thermoregulation that ensures the development of febrile conditions. In aseptic inflammation, fever is a product of only endogenous pyrogen exposure to the body.
However, it should be borne in mind that fever can be caused by the introduction of simpler organic and inorganic compounds into the body. For example, β-tetrahydronaphthylamine, lysergic acid diethylamide (LSD-25), 2,4-α-dinitrophenol, as well as neurotropic drugs such as phenamine, caffeine, cocaine, etc., have these properties. Finally, fever can also be caused by large the amount of NaCl ("salt fever"). Of course, the mechanism of action of these substances on the body is different: this is a direct effect on the centers of thermoregulation, and the effect on metabolic processes. So, for example, 2,4-α-dinitrophenol not only sharply increases oxidative processes, but also helps to uncouple the processes of respiration and phosphorylation.
According to modern concepts, the mechanism of action of pyrogenic substances includes humoral and reflex Components.
Humoral the component lies in the fact that pyrogenic substances, reaching the preoptic region of the anterior hypothalamus with the blood, significantly increase the excitability of cold heat-sensitive neurons and reduce the excitability of thermal ones, as a result of which heat production increases and heat transfer decreases. The body is accumulating heat, which is facilitated by a kind of "misinformation" of the thermoregulation system. The increased sensitivity of cold thermoneurons causes the body to perceive normal ambient temperature as an effect of cooling. As a result, the skin blood vessels spasm, sweating stops, an arbitrary contraction of certain groups of skeletal muscle fibers and skin muscle fibers going to the hair follicles begins, that is, muscle tremors develop - the most effective way of urgent heat production. The patient, even in a warm room, freezes, chills. This is how the first stage of a febrile reaction develops - stage of rise in body temperature (stadium incrementi). Subsequently, against the background of an increase in temperature, the heat transfer mechanisms begin to intensify. After a while, the levels of heat production and heat transfer are compared, and their balance is established at a new, higher level. This is how it develops the second stage of fever is the stage of the plateau (stadium fastigii). The chill stops, the opened cutaneous blood vessels cause the development of arterial hyperemia, and due to the increased flow of warm blood from the deep regions of the body, heat is "dumped" into the external environment.
The duration of the second stage of fever depends on the nature of the pathological process. After a certain period of time, it ends and changes the third stage - the stage of temperature decrease (stadium decrementi), during which the temperature drops to its original value (or even to lower values \u200b\u200bdue to a certain inertness of thermoregulatory systems). The drop in temperature basically contains a significant predominance of heat transfer processes over heat production processes. The main mechanisms responsible for the drop in body temperature are the expansion of skin vessels and profuse sweating. By the end of this stage, heat production also begins to decrease, since dying microorganisms (in the case of the most common infectious fever) cannot supply new doses of exogenous pyrogens, and endogenous pyrogens are destroyed by actively acting enzyme systems. The drop in temperature can be gradual (lysis) and fast (the crisis). A critical drop in temperature, associated primarily with a sharp expansion of skin vessels, is often accompanied by collapse, that is, a state of vascular insufficiency with a rapid and significant drop in blood pressure, which can even lead to death.
In the development of a febrile reaction, a certain role is played by reflex component. In an experiment on animals, it was possible to induce the development of fever in response to the presentation of a conditioned stimulus, if it was repeatedly combined with the introduction of a dose of pyrogen. A sharp slowdown in the febrile reaction was observed in the case when the pyrogen was injected subcutaneously into the previously novocainized area. These facts indicate that the role of the central nervous system and, in particular, the cerebral cortex in the development of a febrile reaction is quite large. Experiments with the administration of neurotropic agents to experimental animals provide additional confirmation of this. Thus, psychostimulants (caffeine, phenamine) enhance the febrile reaction, and deep anesthesia inhibits its development.
The extensive experience accumulated by many generations of doctors who have observed and studied febrile states has made it possible to distinguish several types of temperature curves characterizing the development of fever.
First of all, the classification of febrile conditions is carried out according to the magnitude of the rise in temperature. From this point of view, the following types of fevers are distinguished:
1. Subfebrile fever at which the temperature ranges from 37.1 - 38.0 ° С.
2. Febrile fever with a rise in temperature from 38.1 to 39.5 ° С.
3. Pyretic fever characterized by temperature fluctuations in the range of 39.6 - 41.0 ° С.
4. Hyperpyretic fever - over 41.0 ° С.
Secondly, the classification of the types of temperature curves is carried out depending on their dynamics. ***** 29
1. Febris continua (permanent) - the temperature remains at the same level for a long time, and the difference between morning and evening temperatures does not exceed 1 ° С. This type of febrile curve is observed with croupous pneumonia, influenza.
2. Febris remittens (laxative) - fluctuations between morning and evening temperatures reach 1 - 3 ° C. This type of curve can be, for example, with severe angina.
3. Febris hectica (hectic, depleting) - fluctuations in the levels of morning and evening temperatures reach 3 - 5 ° C. Such a fever is observed, for example, with sepsis.
4. Febris intermittens (intermittent) - periodic, relatively short-term, but very high temperature rises are observed, which alternate with longer periods of their normalization, as, for example, in malaria.
5. Febris undulans (undulating) - characterized by a wave-like dynamics of the temperature curve over several days (as a rule, of a continuous type). This kind of curve is observed, for example, with relapsing fever.
With fever, significant violation of the functions of the body and the activity of its organs and systems.
The cardiovascular system. Tachycardia is observed: an increase in heart rate by about 10 beats per minute with an increase in temperature by 1 ° C. This phenomenon is due to the fact that pyrogens irritate the sinoauricular node. Tachycardia and the increase in cardiac output caused by it contributes to the intensification of the heat transfer process.
Respiratory system. In the second and third stages of the febrile process, deep and frequent breathing occurs, which enhances heat transfer.
Excretory system. At the very beginning of the first stage of fever, due to general vascular spasm, a weakening of urine formation occurs, followed by an increase in diuresis due to the onset of vasodilation and increased renal blood flow. In the second stage of the febrile reaction, despite the expansion of the peripheral vessels, due to the increased secretion of aldosterone by the adrenal glands, sodium is retained, and therefore water in the tissues. Urine flow is reduced. In the third stage of fever, due to a sharp expansion of peripheral vessels and normalization of aldosterone production, urine output increases sharply.
Endocrine system. The activity of the endocrine glands changes with fever to varying degrees, without playing a leading role in its development. The state of the endocrine system largely determines the overall resistance of the body before the onset of the pathological process, thereby indirectly influencing the severity of the febrile reaction. The pathology of individual endocrine glands can increase or inhibit fever. So, for example, in patients with thyrotoxicosis, fever develops more acutely and in a shorter time than in people who do not suffer from this pathology. With hypofunction of the thyroid gland (myxedema), the intensity of fever, on the contrary, is significantly reduced.
For digestive system characterized by a pronounced suppression of the activity of the digestive glands, which leads to a decrease in appetite.
Intensification of metabolic processes in the liver increases with the development of fever and decreases by the end of the third stage.
Functional state nervous system differs at the beginning of a febrile reaction in excitement, which, with a significant increase in temperature, is replaced by inhibition and oppression.
From the side metabolism in general, the predominance of catabolic processes over anabolic processes is noted. This is especially true of protein metabolism, and that is why most febrile conditions are accompanied by a negative nitrogen balance.
As is clear from the definition given at the beginning of this section, fever is a protective-adaptive reaction of the organism, developed in the process of evolution. An increase in body temperature with fever has a beneficial effect on the synthesis of antibodies, phagocytosis, and can also lead to the death of the infection, since microorganisms can develop normally only in rather rigid temperature limits. It is on this feature of fever that pyrotherapy method some infectious diseases, in particular, the last stages of syphilis (progressive paralysis, tabes dorsalis). This method was first successfully applied by the Austrian psychiatrist Julius Wagner-Jaureg, who in 1916 cured patients from progressive paralysis by inoculating them with malaria and causing them a strong febrile reaction.
At present, progressive paralysis of malaria, of course, is not treated using pyrogenic substances for this purpose.
At the same time, fever can also have a negative meaning for the body due to metabolic disorders caused by it, primarily as a result of increased protein breakdown. At hyperpyretic temperatures, immunity is suppressed, there is a deep inhibition of the activity of the central nervous system. Ultra-high fever can lead to the death of the body.
A person is a warm-blooded organism, which means that he can maintain a stable body temperature regardless of external factors. At the same time, each of us is faced with a situation when the temperature rises or, conversely, decreases. MedAboutMe will tell you what these changes can be a symptom of and when you should really see a doctor.
What is thermoregulation
For maintaining thermal homeostasis, constant temperature the human body is primarily responsible for the autonomic nervous system and the hypothalamus. Body temperature depends on the intensity of bioenergetic processes. Therefore, for example, in children, it may normally be higher than in old people, since metabolism slows down with age.
The thermoregulation process is provided in two phases:
- Chemical - due to various metabolic processes in the body, the temperature rises.
- Physical - due to the mechanisms of heat transfer, the temperature decreases. Heat dissipation is carried out with respiration, sweating (evaporation of water from the surface of the skin), etc. The skin plays a primary role here - it is the main heat-exchange organ.
For thermoregulation, hemodynamics is also important - the movement of blood through the vessels. So, for example, when there is a danger of freezing, the body distributes the volumes of circulating blood in such a way that most of it supplies the internal, vital organs. But from the limbs, on the contrary, it casts - this is associated with the danger of frostbite in these areas.
The hypothalamus, a small area in the diencephalon, is responsible for managing the complex process of thermoregulation, namely, for determining when it is necessary to activate cooling or warming mechanisms. The neurons responsible for temperature regulation are located here. Previously, it was believed that the center of thermoregulation is located in the hypothalamus, but today it has been proven that the concept of a single center cannot fully explain all the mechanisms of body temperature stabilization. Heat-sensitive areas are found in the cerebral cortex, hippocampus, amygdala, and even the spinal cord.
External factors are the key cause of thermoregulation disorders in humans. Unlike other warm-blooded animals, in the course of evolution we have become less adapted to temperature changes. Therefore, in critical situations, thermal homeostasis cannot be fully maintained.
Long-term fluctuations of 1-2 degrees from the norm can lead to serious consequences. It should be said that the value of 36.6 ° C used in domestic medicine is not used by foreign doctors. Body temperature can have individual characteristics, and the range of 36.0-37.2 ° C is considered the norm.
- Autonomic dystonia syndrome. Today, VSD (vegetative vascular dystonia) is considered an outdated diagnosis, but some of its signs can be attributed to disorders of the autonomic nervous system.
- Vasomotor neurosis.
- Psychogenic fever.
- Neuroendocrine Disorders.
- Damage to the hypothalamus.
- Organic lesions of the central nervous system (CNS) - tumors, hemorrhages in the hypothalamus, traumatic brain injury.
- Intoxication.
In patients prone to similar manifestations of thermoregulation disorders, there is a strong increase in temperature with infections and inflammatory processes, the inability to quickly eliminate fever with antipyretic drugs, prolonged fever with acute respiratory infections. It should be noted that in children, a high temperature may be a reaction to acclimatization. Moreover, the process of getting used to new conditions can be delayed for months. In addition, for infants, due to imperfect mechanisms of heat transfer, as well as with an increased metabolism, the temperature may rise to 38 ° C (rectal measurement).
Hypothermia is a condition in which the body temperature drops to 35 ° C and below. At the same time, a person develops lethargy, pulse and blood pressure may decrease, general weakness and "weakness" are observed.
A general decrease in body temperature is typical for older people - due to a slowdown in metabolism, it can fluctuate between 35.5-36.5 ° C. This is a physiological process and does not apply to thermoregulation disorders.
Also low temperature body (35.5 ° C) in the morning is the norm for young children.
In the event of a drop in temperature in people up to 60-70 years old, the following diseases or conditions can be suspected:
- Defeat of the hypothalamus.
- Disruption of the central nervous system, in particular, the autonomic nervous system.
- Hypothyroidism (lack of thyroid hormones).
- Parkinson's disease.
- Exhaustion.
- Alcohol intoxication.
- Internal bleeding.
- Iron-deficiency anemia.
A low temperature for several weeks can be observed in people during the recovery period from illness. This is especially true for children and the elderly.
High temperature is one of the main signs of infections, inflammatory processes in the body. How to distinguish a symptom from systemic thermoregulation disorders?
- Other symptoms.
- Psycho-emotional state of a person.
- Reaction to non-steroidal anti-inflammatory drugs.
- General blood analysis.
- Virus antibody test or bacterial culture.
Indeed, thermal imbalance occurs due to damage to internal organs involved in heat regulation.
Normally, a person's temperature should be kept within 36.2-37 degrees. Thermoregulation of the human body is the ability of the body to control heat exchange so that the temperature does not exceed the permissible value. Thermal equilibrium is achieved in such ways: by changing the volume of blood circulation and the amount of sweat secreted, due to biochemical processes. At the same time, all types of heat exchange are responsible for the normalization of the balance at once, only the degree of their involvement differs.
Chemical heat exchange is carried out through the generation of energy. All organs are involved in this process, especially when blood passes through them. The maximum amount of energy is produced in the striated transverse muscles and liver. Controlling the balance of body temperature through the release of thermal energy is the physical regulation of heat. It is carried out by direct exchange of heat with cold objects, air, infrared radiation. This can also include breathing and evaporation of sweat from the skin.
How thermal equilibrium is maintained
The internal temperature is controlled by special sensitive receptors. Most of them are located in the skin, oral mucosa, upper respiratory tract... If the environmental conditions do not correspond to the norm, the receptors send a signal to the brain and a feeling of overheating or hypothermia appears. The processes of heat generation or release are triggered by the thermoregulation center.
It should be noted that the mechanisms of energy formation also occur due to certain hormones. For example, thyroxine increases heat production by accelerating metabolic processes. Adrenaline has the same effect, but it is carried out by accelerating oxidation processes. In addition, adrenaline constricts the blood vessels in the skin, which also helps to retain heat.
Biochemical method
Biochemically, thermal equilibrium is achieved by increasing the oxidation processes that occur in the human body. Outwardly, this phenomenon is manifested by tremors in the muscles, which appears if the body is hypothermic. As a result, more heat is supplied to the body to achieve balance. If heat is not generated when the ambient temperature drops, then this indicates an imbalance.
Enhancing blood circulation
The imbalance in heat is also regulated by a change in the intensity of the volume of blood supplied, which transfers energy from organs to the surface of the body. The blood circulation is enhanced by the dilating / constricting vessels. If the temperature needs to be reduced, expansion occurs. To increase heat, constriction. The volume of blood supplied can change thirty times, inside the fingers - up to six hundred times.
Sweat rate
Physical regulation of heat exchange can also occur due to increased sweat production. In this case, heat equilibrium is achieved through evaporation. The body's evaporative cooling mechanisms are extremely important to the body. For example, if the ambient temperature is at 36 degrees, heat exchange from a person to the external atmosphere is carried out mainly due to the release of sweat and its evaporation.
Permissible range of environmental parameters
At different limits of environmental parameters, thermoregulatory mechanisms cope with maintaining thermal equilibrium. Under air conditions, when physical thermoregulation determines the optimal level of metabolic intensity in a person, tension and other negative sensations do not arise. Such conditions are considered optimal or comfortable.
A zone in which the external environment almost completely takes away the heat released by the body, but at the same time the regulatory mechanisms keep the body temperature under control, is considered acceptable as comfortable.
Conditions under which there is a violation of the thermal equilibrium of the body are considered uncomfortable. If the thermoregulatory mechanisms operate under low tension, then the conditions are defined as permissibly uncomfortable. Such an environment is characterized by meteorological parameters that do not exceed the permissible norm.
If the parameters exceed the set values, then the heat regulation systems operate in an enhanced (intense) mode. Such conditions cause perceptible discomfort, and the heat balance is disturbed. Hypothermia or overheating of the body occurs, depending on which direction the thermal equilibrium is disturbed, plus or minus.
Causes of heat imbalance
Small changes in heat production and its transfer to the atmosphere occur during physical exertion. This is not a violation, since in a calm state, during rest, all thermoregulation processes quickly return to normal.
Disturbance in heat exchange, as a rule, appears as a result of systemic diseases, accompanied by inflammatory processes in organism. Nevertheless, the situations that caused strong rise body temperature with inflammation, it is incorrect to consider pathological.
Fever and fever appear to stop the growth of cells infected with bacteria, viruses. In fact, these structures are a natural defense reaction of the immune system, and treatment is not required here.
Indeed, thermal imbalance occurs due to damage to internal organs involved in the regulation of heat - the hypothalamus, brain (spinal and cerebral), pituitary gland.
Physical and biochemical regulation of heat exchange is disrupted if there is mechanical damage to the body, the formation of tumors, hemorrhages. Additionally, they increase the violation of diseases of the cardiovascular and endocrine systems, disruptions of hormonal levels, physical overheating / hypothermia.
Pathology treatment
To restore the correct course of heat regulation mechanisms, appropriate treatment is required, which is prescribed after clarifying the causes of the resulting disturbance in the production and release of thermal energy. The doctor, before determining what treatment is required, will issue a referral to a neurologist, recommend laboratory tests and prescribed medical examinations. Only this approach will allow planning correct treatment, which will help restore natural thermoregulation systems.