Everyone knows what stress is.
And at the same time – not all.
The fact is that the scientific concept of stress is very different from the everyday one. In everyday life, stress is called any hassle. Shouted chief of – stress. The son got a deuce – stress. The cake didn’t rise in the oven – also stress. Well, about the hour standing in traffic at all to say nothing, it’s such a stress that all stress stress.
In fact, stress has nothing to do with the hassle. Stress is a state of increased tension of the body (including the nervous system), which occurs in response to various adverse factors, physical or mental.
Are you hungry? So you’re under stress.
You are cold, so much so that you have a tooth on the tooth does not fall? That’s stress. A shiver – an attempt to protect the body from hypothermia by increasing muscle activity, in which heat is released. Muscles “tremble”, that is – move, body temperature rises.
The chief shows aggression towards you – shouts at you, knocks a fist on a table? It’s another kind of stress. In response to someone else’s aggression you, more precisely – your body is preparing to fight or to flee. Heartbeat quickens, resulting in blood begins to move through the vessels more intensively. Also, the frequency of respiratory movements increases – the gas exchange between blood and air becomes more intense, the blood is purified from carbon dioxide faster and is better saturated with oxygen. Peripheral blood vessels constrict, resulting in a redistribution of blood flow in favor of the muscles and vital organs (heart, lungs), which work with increased load… And so on.
But the deuce brought by your child from school, in a purely scientific understanding of stress is not, because your body does not need to mobilize in response to the impact of this factor. You do not need to get food, warm up or run away… Yes, of course, certain negative emotions from getting a child deuce you will experience, but still it will not be a stressful situation, and nervous tension.
Stress is a response. “From scratch”, i.e. without cause, without any influencing factors stress can not occur.
Stress is a protective reaction, because the meaning of stress is to protect yourself from the impact of an adverse factor, in order not to suffer and not to die.
Stress is an adaptive response because it helps the body adapt to environmental conditions.
Endocrinologist Hans Selye, who created the doctrine of stress, called stress “nonspecific response of the body to any demand presented to him.” Non-specific, please note! Stress reaction is not narrowly focused, but General.
In stress, there are three stages:
• the stage of anxiety, during which the mobilization of adaptive capacity of the body;
• the stage of resistance or adaptation, during which the body resists adverse effects, the body’s resistance to the influence of the factor that caused stress, increases;
• the stage of exhaustion, which begins after the adaptive capacity of the body will be exhausted (all the reserves of the body, unfortunately, are limited); this stage is characterized by a decrease in the body’s resistance to the influence of the factor that caused stress.
Stress caused by positive emotions is called “eustress” and negative – “distress”. Yes, unlike domestic “stress”, scientific stress can be positive. Sexual intercourse is an example of eustress.
With what is stress, we have figured out and now move on to our subject – to stress hormones, the production of which increases under stress. Stress hormones four – adrenaline, noradrenaline, cortisol and prolactin.
Adrenaline (or epinephrine) is the main hormone produced by the adrenal medulla. Adrenaline is a fairly simple substance from a chemical point of view. Its molecule is relatively small and consists of only twenty-five atoms – nine carbon atoms, thirteen hydrogen atoms, three oxygen atoms and one nitrogen atom. The gross formula (that is, the chemical formula that reflects only the composition, but not the structure of the substance molecule) of adrenaline is as follows: C9H13NO3.
The adrenaline molecule contains an amino group – NH, so adrenaline (as well as noradrenaline, and dopamine, which will be discussed below) refers to catecholamines – derivatives of pyrocatechin with the presence of an amino group in the molecule. So deep into chemistry we could not delve, but the fact that the name “catecholamines” is used not only in scientific but also in popular literature. So you have to understand what it is.
Small adrenaline, but it was incredible. What he doesn’t know how!
Sit back and start reading about what adrenaline does in our body.
But before you start listing the functions of adrenaline, I must say that in our body there is not one type of adrenoreceptors – receptors that can bind to adrenaline and noradrenaline, and as many as five! Adrenoreceptors are indicated by the Greek letters “α” and “β”, as well as numbers.
α1-adrenoreceptors are found in the smallest arteries, which are called “arterioles”. Stimulation of these receptors (i.e. their interaction with adrenaline) leads to narrowing of arterioles, spasm of their walls.
α2-adrenoreceptors, which are also in the arterioles, in interaction with adrenaline produce the opposite effect – expand the lumen of the arterioles.
β1-adrenergic receptors are found mainly in the heart muscle. Their stimulation leads to an increase in heart rate and strength. Also, these receptors are in the kidneys.
β2-adrenergic receptors are found in the smallest bronchi, which are called “bronchioles” (suffix “-Ola” has a diminutive value). Their stimulation causes dilation of the bronchial tubes. Also, these receptors are in the liver, where stimulation increases the decay of glycogen and thereby increase the flow of glucose into the blood. Glycogen is a carbohydrate with a huge molecule consisting of many glucose molecules. It is a form of stock of glucose in animals. In plants for this purpose is starch.
β3-adrenergic receptors are found in adipose tissue. Their stimulation increases the breakdown of fats, accompanied by the release of energy.
Adrenoreceptors are present in all organs, in all cells of our body! Not every hormone can boast of such popularity.
The question arises – why do you need so many adrenoreceptors? Why so complicated?
And in order to solve several problems at a low cost (with the help of one substance). It’s actually very reasonable. In the economy it is called – prudent approach. In the body everything is arranged logically and rationally. Even such mutually exclusive actions as, for example, narrowing and expansion of blood vessels under the influence of adrenaline on different types of adrenoreceptors, did not occur by chance.
And now – the functions of adrenaline. On the items.
The first function is the adrenalin causes a marked constriction of the vessels of the abdominal cavity, skin and mucous membranes, and slightly constricts blood vessels of skeletal muscle. It is clear for what it becomes? To redistribute blood flow, to the blood went to where it is especially needed under stress – to the muscles, to the heart, to the lungs, to the brain. A slight narrowing of the vessels of skeletal muscles can not be taken into account, because it is expressed weakly. For simplicity, we can assume that adrenaline does not act on these vessels. Because of the massive constriction of blood vessels increases blood pressure. Hydraulics and nothing more – reducing the volume of a closed system leads to an increase in pressure in it.
In fact,the effect of adrenaline on the body is much more complicated than is described here. For example, along with the actions that lead to increased blood pressure, adrenaline also contributes to its reduction – remember the α1 and α2-receptors in the arterioles. But we consider only the basic, the dominant, the very essence, without going too deep into the jungle.
The function of the second – epinephrine dilates blood vessels of the brain, so the brain received more blood, more power.
Function three – adrenaline increases the heart rate and increases their frequency, which also leads to an increase in blood pressure – if the pump (and the heart, no matter how it is sung and what properties it may be attributed, there is nothing like a four-chamber pump) begins to work harder, the pressure in the system increases. Blood brings oxygen and nutrients to the organs, and in return takes away all unnecessary – the final products of metabolism (carbon dioxide, urea, uric acid, water). The more intense the flow of blood, the better supplied and better cleaned organs.
Function four – adrenaline causes relaxation of the muscles of the bronchi, intestines and bladder. Relaxation of the muscles of the bronchi, as you may have guessed, leads to their expansion, which increases the gas exchange between blood and air. Relaxing the muscles of the intestine slows digestion. Digesting food is not the most important activity under stress. It can be slowed down, it can be postponed for the future, post-stress time. Relaxation of the muscles of the bladder to increase its volume. The feeling of a full bladder, in other words – the urge to urinate, is a feeling of discomfort, inconvenience, which in a stressful situation is better to avoid, so as not to be distracted from the main task – to protect and save yourself.
Function five – adrenaline causes the contraction of the radial (circular) muscle of the iris, which leads to the dilation of the pupil. As a result, the eyes get more light, that is – improved vision.
The fact that the muscles of different organs adrenaline acting differently due to the presence in these muscles of receptors of different types. For example, in the muscles of the bronchi and intestines are β2-receptors, and in the radial muscle of the iris – α1-receptors.
The function of the sixth – adrenaline takes broad participation in the processes of metabolism. He does everything possible to ensure that the blood was as much glucose, and helps the cells of the body to capture and use it. Along the way, adrenaline stimulates the breakdown of fats and inhibits their synthesis. The breakdown of fats is accompanied by the release of energy, and synthesis – absorption. Thus, adrenaline tries to give the body as much energy as possible, which can be used (may be needed) in a stressful situation. Any stress is accompanied by increased energy consumption.
Function seven – with prolonged exposure to moderate amounts of adrenaline causes an increase in cardiac and skeletal muscles, that is, contributes to the adaptation of the body to increased physical activity.
Function eight – with prolonged exposure to high amounts of adrenaline causes increased protein breakdown, which leads to a decrease in muscle mass, weight loss until exhaustion.
It would seem – why do we need such a function? What good does it do but harm? What good is exhaustion?
Of course, there is nothing good in exhaustion. But let’s look at the problem from the other side. For what reason will adrenaline be present in the body in high concentrations for a long time? Of course – because of repeated stress. As mentioned above, any stress is accompanied by increased energy consumption. If stresses follow one after another, then the glycogen reserves are depleted, all fats are burned and the turn of proteins comes, the last, we can say – inviolable, energy reserve. This is adrenaline and contributes to their decay. What do you want me to do if I can’t get any more power?
Function nine – adrenaline has a stimulating effect on the Central nervous system – invigorates, activates, promotes mental mobilization. Figuratively speaking, adrenaline sends a signal to the brain: “Alarm! Be on the lookout!»
Function tenth – adrenaline has a pronounced anti-allergic and anti-inflammatory effect. It inhibits the release of substances involved in allergic and inflammatory processes, as well as reduces the sensitivity of cells to these substances.
Ten is not the limit. Read on!
Function eleven – adrenaline reduces blood filling of the cavernous bodies of the penis, thereby reducing erection. Men can not be surprised – well, how so? Why did nature provide this function? Nature, we can say, did not provide for this function. The fact is that this effect is manifested only with the introduction of large doses of adrenaline directly into the cavernous body and is important only in medicine. With the release of adrenaline into the blood, the erection does not reduce, but even slightly increases, because due to the redistribution of blood flow to the penis, more blood flows to the penis.
Function twelfth – adrenaline has a stimulating effect on the blood coagulation system, which in combination with the spasm of arterioles is expressed in stopping or weakening bleeding, that is – in reducing blood loss.
Function thirteen (and the last of the most important functions that we consider) – adrenaline through the hypothalamus stimulates the production of adrenocorticotropic hormone in the pituitary gland. Frightening its long name “adrenocorticotropic” is formed from two Latin words and one Greek: “adrenalis” (“adrenal”), “cortex” (“bark”) and “tropos” (“direction”). It is translated as “directed to the adrenal cortex”, that is – to their cortical substance. And for what the pituitary gland will direct to the cortical substance of the adrenal glands a special hormone? Of course, for stimulation. Adrenocorticotropic hormone stimulates the production of adrenal cortex hormones such as cortisol, cortisone, corticosterone, progesterone, androgens and estrogens.
Cortisone and corticosterone play a very minor role in our body. So minor, that attention not deserve. About progesterone, androgens and estrogens (Yes, sex hormones are produced in the adrenal glands), we will talk in other chapters. And now we’re interested in cortisol – another stress hormone. See how cleverly arranged – adrenaline stimulates the production of his assistant in the fight against stress, and cortisol, in addition to its main action, increases the effect of adrenaline. Evaluate – what is useful is mutual! Amazing!
We’ll come back to cortisol a little later. In the meantime, let’s talk about the use of adrenaline in medicine.
Due to its versatility and relative ease of obtaining (from the adrenal glands of cattle) adrenaline is widely used for medicinal purposes. It is used for acute allergic reactions (scientifically they are called allergic reactions of immediate type), for relief of bronchial asthma attacks, for “starting” the heart when stopping, with a decrease in the level of glucose in the blood, with priapism – a long and painful erection, not associated with sexual arousal, as well as bleeding from the surface vessels of the skin and mucous membranes due to the spasm of arterioles caused by it.
And now think – whether it is possible to apply adrenaline at damages of large blood vessels?
Of course not, in any case it is impossible, because the spasm of arterioles, caused by adrenaline, will increase blood pressure, which, in turn, will increase blood loss – it will flow more intensively from the damaged vessel.
Adrenaline has an anti-stress effect for a very short time – just a few minutes. The fact is that almost from the moment of adrenaline in the blood starts the process of its destruction with the help of special enzymes. The same thing happens with noradrenaline. This is done in order to prevent depletion of the body, because at the peak of tension it is impossible to exist for a long time.
Noradrenaline (C8H11NO3) from a chemical point of view is considered a precursor of adrenaline, because it has a simpler structure – does not contain the so-called methyl group (-CH3) in the nitrogen atom. Instead of a methyl group, a nitrogen atom is bound to another hydrogen atom:
Because of the similarities in the structure of the main functions of norepinephrine coincide with the functions of adrenaline, but there are differences. Noradrenaline mainly binds to α-receptors. It has a more pronounced vasoconstrictor effect than adrenaline, but much weaker effect on metabolism, the heart, bronchi, intestines, etc. Because of this in medicine, noradrenaline is mainly used in cases where you want to dramatically and significantly increase blood pressure. If adrenaline can be called a “broad-spectrum hormone” or “generalist”, noradrenaline – specialist narrow profile. In fact, it can only raise blood pressure, but it does it remarkably well – much faster and much stronger than adrenaline.
You may ask – why do we need to increase the pressure, because of this only problems arise? But it is not necessary to confuse pathological, that is painful, increase of arterial pressure with physiological, normal. Here’s a simple example – you lay down for a while and then stood up. The transfer of the body from the horizontal to the vertical position should be accompanied by an increase in blood pressure, so that the blood continues to flow to the brain in sufficient quantities, otherwise it may faint.
Here are the figures – if in the supine position the level of norepinephrine in the blood is from 0.41 to 4.43 nmol/l [8] (depending on age and other factors), then in the standing position – from 1.18 to 10 nmol/l. When the body is vertical, the content of norepinephrine in the blood increases more than twice.
Noradrenaline is also involved in the regulation of the waking process, but not as a hormone, but as a chemical.
Adrenaline is often called the “hormone of fear” for the reason that its release occurs both with intense physical activity, and with any strong excitement (in particular – with fright). And norepinephrine is called “the hormone of rage”, because it is believed that as a result of the release of norepinephrine in the blood there is a reaction of aggression.
In fact, this division is very conditional and does not reflect the real situation. Fear and fury (and an orgasm if you want) are the result of complex, combined, coherent interaction of various hormones. To call adrenaline “the hormone of fear,” and noradrenaline – the hormone of rage,” is as stupid as to say that the front wheels of a car are used to move forward and the rear wheels are used to move backward. Both back and forth the car rides on all four wheels, just as all stress hormones are involved in providing a stressful response to the body. Just so and not otherwise.
Most readers of this book are clearly familiar with terms such as “adrenaline addiction” and “adrenaline addiction”. Adrenaline junkies called all sorts of thrill-seekers, thrill-seekers and risk-takers. It is believed that these people experience euphoria when increasing the level of adrenaline in the blood and therefore conquer the mountain peaks, jump with a parachute, climb roofs and spires, fly hang gliders, participate in rodeos, etc. the Risk does not scare them, they need adrenaline, as much as possible adrenaline…
So, let’s start with the fact that there is no “adrenaline addiction” and therefore “adrenaline addiction”. In any case, the official medical science of the term “adrenaline addiction” does not use and does not recognize. Yes – imagine! Where did it come from? “Adrenaline addiction” was invented by psychologists. Not as a diagnosis, but as a professional jargon conditional “label” for patients who experienced an irresistible thirst for acute vivid sensations brought by dangerous, risky actions.
Why “adrenaline addiction” – a label conditional and official diagnosis can not be considered? Yes, because no dependence adrenaline (and also norepinephrine) to cause not capable of. Craving for risky and dangerous has a psychological origin (no wonder this dependence was invented by psychologists). It’s not the adrenaline, but the psychological problems of a particular person, the motives that encourage a person to risk again and again. Many extreme people (the author deliberately refused the words “the vast majority”, because he did not have at hand the relevant statistics), paradoxically it sounded, lack self-confidence. In order to gain this confidence, they are forced to perform various extreme actions. Their behavior is about. Uncertainty leads to action (for example, to jump with a parachute how to overcome the fear of heights), after extreme actions, a period of calm, i.e., a period of confidence, after some time uncertainty rears its head and encourages you to make new extreme action… Adrenaline here, we can say nothing at all. And anyway, if it was the adrenaline, the dependent would put in an IV and received their portion of joy. It’s easier than conquering Everest, skydiving or skateboarding on the edge of a skyscraper roof.
The status of the medical diagnosis of “adrenaline addiction” was given by the authors of numerous articles about extreme sports and extreme sports. But, reading articles in mass media, it is necessary to understand that “newspaper” medicine strongly differs from official.
And now…
If you thought we were going to talk about cortisol, you were wrong. We’ll get to cortisol later. And now we’re going to talk about dopamine, the chemical precursor of norepinephrine.
From noradrenaline dopamine is characterized by the absence of one hydroxyl group – OH. The difference is small, but very significant.
As a hormone dopamine is much inferior to adrenaline. In all respects. And the degree of action on adrenoreceptors, and the number of functions. Norepinephrine is also inferior.
Arterioles dopamine narrows, but not as much as norepinephrine.
The strength and heart rate of dopamine increases, but not as much as adrenaline.
Dopamine relaxes the muscles of the intestine, but not as much as adrenaline.
But dopamine is able to expand the renal vessels, increasing their blood flow and filtration, which results in urine. Also dopamine increases the excretion of sodium ions in the urine. This function is due to the presence of special dopamine receptors in the kidneys.
We have listed the main functions of dopamine as a hormone. A little, isn’t it? But the fact that his fame dopamine was not as a hormone, but as a neurotransmitter – a biologically active substance involved in the transmission of nerve impulses.
What is remarkable – the dopamine, which acts as a hormone produced by the adrenal glands, as well as, in very small quantities, kidneys. And the dopamine, which acts as a neurotransmitter, is produced by the nerve cells of the brain. The reason for this separation is that dopamine is unable (or rather, almost unable) to penetrate the so-called blood-brain barrier that separates the circulatory and Central nervous systems.
The blood-brain barrier is formed by cells lining the inner surface of blood vessels. If in other organs between these cells and then there are gaps – holes and cracks through which various substances can penetrate, then in the vessels that feed the brain, the cells are adjacent to each other tightly, without any gaps. Transport of substances from the vessels of the brain is not through the holes and cracks, and through the cells. First, the substance gets from the blood into the cell, and then from it goes to the brain. If we compare this process with the crossing of the state border, we can say that in the whole body this transition is carried out through the holes in the fence, and in the brain – only through the border points and nothing else. The blood-brain barrier is not a quirk of nature, but a necessary protective mechanism that prevents the penetration of such an important organ as the brain, microorganisms, toxins, etc.
As a neurotransmitter, dopamine causes feelings of pleasure or satisfaction. It is produced in large quantities in the body during a positive, pleasant experience – eating delicious food, sex, watching an interesting picture, winning the game, etc. Dopamine production causes not only a direct experience of positive experience, but also thoughts about it – memories or even dreams. So that dream and in fact not harmful. As a “neurotransmitter of satisfaction” dopamine is part of the so-called “reward system” (aka – “internal reinforcement system”), which regulates our behavior through positive reactions to actions. This regulation is based on the desire to relive a positive experience. The reward system is closely related to learning – when pleasure is received in the cerebral cortex, certain cause-and-effect associations are formed that encourage us to experience it again.
Why do you think motor activity, starting with a simple walk and ending with participation in triathlon competitions, brings us satisfaction? Because during it increases the production of dopamine by brain cells.
Also as a neurotransmitter dopamine is involved in providing cognitive activity – mental processes that lead to understanding something. Dopamine acts as a kind of “attention switch” to help us move from one stage of cognitive activity to another. When dopamine deficiency slow mental processes and have perseverancia – “stuck” in the minds of some the thought and repeated it aloud, the repetition, the monotonous repetition of the same movements, etc. If you are often “stuck” on the same thoughts, then maybe you should check if there is enough dopamine is produced by cells of your brain.
The action of many drugs is associated with an increase in the production of dopamine (up to tenfold), which causes a pronounced sense of pleasure. Some drugs, as well as antidepressants, can block the natural breakdown of dopamine in the body, thereby increasing its concentration. Wherever there is talk of pleasure, there is dopamine. Of course, artificial “defeminization” of the body by using drugs or nicotine causes the body great harm. If you want to have fun without harmful consequences, then go in for sports, realize your abilities, travel, enjoy delicious food, read interesting books (such as this one), watch interesting movies, love, have fun… there are a lot of Safe natural ways to have fun.
In 1997, Professor of Cambridge University Wolfram Schultz put a series of very interesting experiments involving monkeys.
In one experiment the monkey developed a conditioned reflex according to the classical scheme – after the light signal the monkey received a portion of juice. Juice is a pleasure that increases the production of dopamine.
What do you think will happen if you give a monkey juice without a preliminary light signal? Logic dictates that without signal, i.e. – without training, dopamine should be produced less. But in fact (Ah, how often the result of the experiment refutes expectations!) unexpected giving juice produce more dopamine than when submitting pre-alarm.
And that’s not all.
Schultz revealed another “paradoxical” feature. If at the stage of the formation of the conditioned reflex, the production of dopamine increased in response to drinking juice, then after the reflex was formed, the production began to increase after the signal was given, even before the juice was given. Drinking juice did not cause an additional increase in dopamine production.
If after the alarm the monkey did not give juice, the next signal of dopamine produced less.
Actually, Schultz was measuring not the amount of dopamine produced in the brain, but the activity of dopamine nerve cells in the brain using implanted electrodes, which was easier. However, we are talking about the production of dopamine not only for the sake of simplicity, but also because the increase or decrease in cell activity is determined by the amount of dopamine produced.
In another experiment, the monkeys were given different portions of juice each time. In those cases, when the portion was large, dopamine production increased dramatically.
In the third experiment, the monkey pressed the lever when a certain combination of figures appeared on the monitor screen. If the task was performed correctly, the monkey received juice. It turned out that the production of dopamine increases not when drinking juice, but when the desired combination of figures appears on the screen.
His experiments Schultz showed that the regulation of dopamine production by brain cells – a very complex process involving higher parts of the Central nervous system (cerebral cortex).
This is where we say goodbye to dopamine and move on to cortisol, the third of the major stress hormones.
About cortisol will be discussed in two chapters – in this and in the Chapter on “hormones-engineers”, that is, those hormones that regulate metabolism in the body.
Cortisol or hydrocortisone is produced by the cortical layer of the adrenal glands under the influence of the adrenocorticotropic hormone of the pituitary gland. Cortisol refers to the so-called “steroid hormones”. This group also includes sex hormones, androgens and estrogens. The word “steroids” is probably familiar to all readers. Most often in everyday life it can be found in the phrase “anabolic steroids” are substances used to improve athletic performance, that is – to build muscle.
If you ask a person who has no medical or chemical education to define the word “steroid”, the answer is likely to be: “These are substances with high biological activity.” That may be so, but not quite. Many steroids have high biological activity, but this property does not make them steroids. Steroids are substances derived from cyclopentanoperhydrophenanthrene. Hardly anyone of the readers, except biochemists will be able to correctly pronounce the word “cyclopentanoperhydrophenanthrene” even on the third attempt. For convenience, you can use more euphonic synonyms – “steran” or “gonan”.
From the word “steran” came the name of derivatives – steroids, which translated from Latin means “steran-like”.
As you can see, this molecule consists of four hydrocarbon rings – three six-membered and one five-membered. Steran is a saturated hydrocarbon, that is, all the carbon atoms in its molecule are interconnected by simple ordinary bonds. Saturated hydrocarbon compounds do not react as actively as unsaturated ones, in molecules of which, in addition to ordinary bonds between carbon atoms, there are double and triple ones. But, nevertheless, derived sterane know a lot. An interesting detail – as a starting component for the synthesis of most steroid hormones acts Great and Terrible cholesterol, which enters our body with food, as well as produced in the liver (mainly), as well as in the small intestine, skin, kidneys, gonads and adrenal glands.
Steroid hormones produced in the adrenal cortex are called glucocorticoids or glucocorticosteroids. Prefix “glyuko-” these substances were due to its ability to increase the level of glucose in the blood.
The official name of the cortisol for the uninitiated, it sounds weirder than the word “cyclopentanoperhydrophenanthrene” – 4-pregnen-11β,17α,21-triol-3,20-dione. How? If someone does not know, then such long and complex names of organic compounds are given not for the sake of bullying the uninitiated, but for a specific purpose and according to certain rules. Hearing the name “cyclopentanoperhydrophenanthrene”, the chemist will immediately present in the compound. The name is a code or, figuratively speaking, a passport of a chemical.
What is the role of cortisol as a stress hormone?
First of all – in supplying the body with energy, which is especially necessary in stressful situations. All the action of cortisol on metabolism is aimed at the extraction of energy resources. Cortisol increases the level of glucose in the blood and prevents its capture by cells of those organs, the value of which under stress is relatively small, stimulates the breakdown of fats and proteins (more detail we will talk about all this in the Chapter on the effect of hormones on metabolism). The purpose of all these actions is to obtain sufficient energy necessary for the intensive work of the muscular, cardiovascular and respiratory systems, as well as the brain.
Cortisol is the intendant of our body. All those incredible feats that people perform in stressful situations, are due to the energy, courtesy of the body cortisol.
Cortisol is a very clever quartermaster. It not only mobilizes energy resources in a stressful situation, but also accumulates them during the normal life of the body. Cortisol increases appetite. When you want to eat after intense physical activity or at the peak of negative emotions, you know – this is “to blame” cortisol. In addition to increasing appetite, cortisol also contributes to the formation of fat accumulation, because it increases the level of glucose in the blood. And glucose is such a product, the excess of which our body in normal life does not remove to the environment, and puts a reserve in the form of fat.
You never wondered why our body lays exactly fat, not protein and not carbohydrate? Is it accidental or natural? Of course – naturally, because fat is the most convenient, the most capacious, so to speak, a form of energy storage. If the cleavage of 1 gram of glucose or protein (to the final product) releases 17.6 kJ energy, the cleavage of 1 gram of fat – 38.9 kJ!
For any warehouse is important not only its capacity, but also the convenience of loading and unloading. According to the complexity of energy extraction during the splitting of fats occupy an intermediate place between glucose and proteins.
But back to cortisol. We have dealt with its procurement function. But this “stress” cortisol function does not end. In addition to providing the body with energy, cortisol increases blood pressure, and does so in two ways, acting directly and indirectly. Directly cortisol increases the sensitivity of vascular receptors to noradrenaline, and indirectly – contributes to the delay in the body of sodium ions, stimulates the reverse absorption of sodium ions into the blood in the kidneys.
Here we need to make a small digression and explain what is reverse absorption in the kidneys and why increasing the concentration of sodium ions in the blood causes a rise in blood pressure. Those who knows it all, you can skip the explanation.
The surface cortical layer of the kidney contains the so-called “renal glomeruli” – a set of capillary loops, forming a filter for fluid, passing from blood to kidney. Each ball is surrounded by a connective tissue capsule.
If you look at the picture carefully, you will notice that the carrying artery of the renal glomerulus is much already bringing. Due to the difference in the diameters of the arteries in the glomerulus, increased blood pressure is created and the liquid part of the blood is filtered through the walls of the capillaries [10]. In the glomerulus formed the so-called “primary urine”, which, in addition to harmful substances to be excreted from the body (urea, uric acid, etc.), also contains useful. Primary urine is a blood plasma only without proteins, large molecules of which are not able to pass through relatively small pores in the walls of the renal capillaries.
From the capsule leaves a long convoluted tubule, braided blood vessels. While the primary urine passes through this channel, nutrients from it have time to suck back into the blood. This process is scientifically called “reabsorption”, which translates from Latin as “reverse absorption” or “reverse absorption”. As a result of reverse absorption, secondary or “final” urine is formed, containing substances unnecessary to the body, dissolved in water.
We’ve dealt with the back suction. And in order to understand why the increase in the concentration of sodium ions in the blood causes an increase in blood pressure, you need to remember about such a physical phenomenon as osmosis.
If two solutions with different concentrations of the same substance are separated by a partially permeable (semipermeable) membrane, that is, one through which only solvent molecules can pass, then the process of outflow of the solvent molecules from the solution with a lower concentration of the dissolved substance into the solution with a higher concentration will begin, since the communicating solutions tend to equalize the concentrations of the substances dissolved in them.
Pay attention to the partial permeability of the membrane, through the pores in which only solvent molecules can penetrate, but not the dissolved substance. This is important. Now imagine the role of such a membrane capillary wall. Inside, that is, in the blood, the concentration of sodium ions is high, and outside, in the intercellular space – low. To equalize the concentration of sodium water molecules from the intercellular space rush into the blood. Sodium ions can not enter the intercellular space, since the walls of the capillaries are impervious to them. As a result of the absorption of water from the intercellular space will increase blood volume. And what leads to an increase in the volume of fluid in a closed hydraulic system? To increased pressure!
In addition to increasing blood pressure and energy management, cortisol also has an anti-inflammatory effect, which manifests itself with its increased content in the blood. But collagen slows the healing of wounds due to the ability to destroy collagen fibers. Collagen is a protein of thread-like structure, actively involved in the healing process. Scars, remaining in the place of healed wounds, consist of collagen.
Cortisol is produced under the influence of the adrenocorticotropic hormone of the pituitary gland, the production of which, in turn, is stimulated by corticoliberin, produced in the hypothalamus, where all the threads of endocrine control in our body converge.
Who do you think controls the production of all these liberins in the hypothalamus? Hormones themselves! On the principle of negative feedback. Increasing the level of hormone in the blood reduces the production of appropriate liberin in the hypothalamus and Vice versa. Our body is a self-regulating system.
Prolactin, also called lactotropic or lactogenic [11] hormone, is produced in the pituitary gland. According to the chemical structure, it is a protein. The main function of prolactin in women is to induce and maintain milk production in the mammary glands. Note – prolactin is produced in both women and men, but in smaller quantities. We will talk in detail about prolactin in subsequent chapters, and now we will touch only on its role in stress.
Why in stressful situations increases the production of prolactin? So women can have more milk? Not for that. The stress value of prolactin is the inhibition of pain sensitivity. The analgesic effect of prolactin in the first place is necessary to ensure that nursing would not feel severe pain when biting the nipple during feeding. But this effect is generalized, that is – applies not only to the nipple area, but also to the entire body as a whole. Agree that the oppression of pain sensitivity under stress is important. When a stressful situation there is the opportunity to fight, and while fleeing low pain sensitivity is not hurt.
In conclusion, a few words about the growth hormone. The production of somatotropin increases with stress. This hormone comes to the aid of cortisol and adrenaline, helps them to provide the body with energy. Remember that somatotropin increases the level of glucose in the blood, as well as stimulates the breakdown of fat. Supplying the body with energy in a stressful situation is a task of great importance, and the solution of such tasks is usually entrusted not to one employee, but to a group.
You can exhale and relax. The stress is behind us. In the next Chapter we will focus on hormones as the defenders and the hormones of the pests.