Acquaintance with hormones can be organized in different ways. It is possible to consider separately the organs of the endocrine system and find out what hormones they produce. This is how medical students usually study the endocrine system. But there is another way – not to study the organs and hormones.
Now many readers smiled and thought: “What is the difference – that forehead, that forehead!”. And some, perhaps, expressed this thought aloud.
In fact, there is a significant difference. The same hormones are produced by different glands, so if you move “on the organs”, then inevitably there will be repetitions that complicate the assimilation of the material. Excess always complicates learning. And we are not talking about endocrinology in General and not about the organs of the endocrine system in particular, but about hormones, these invisible mediators that control all processes in our body. So it is more correct and logical (in our case) to get acquainted directly with hormones, not with organs. And to get acquainted not in alphabetical order (we do not have an encyclopedia but rather a friendly conversation about hormones), but by professions of hormones, that is – by their functions. The meaning of the existence of any hormone lies in the functions performed by it, and not in the place of birth, that is – the place of production.
In this Chapter, we will focus on the hormones-builders, which stimulate the growth of the body, and their antagonists – hormones-brakes, which slow down this growth.
Growth of the organism, as well as all other properties, is determined by genes – guardians of the genetic information. There are more than 35,000 genes in the human body. The gene is a site of a giant molecule of deoxyribonucleic acid (DNA) responsible for the synthesis of one protein (the definition is approximate and simplified, but gives an idea of the gene). DNA molecules form structures called “chromosomes” and are found in the cell nucleus. One chromosome is one DNA molecule. Normally, the chromosomes should be forty-six.
If we compare man with the multi-storey building (forgive the author this comparison is made only to facilitate learning, not to humiliate the human race!), the genetic information can call the project for the construction of the building. Genes contain all the necessary information regarding the construction, all to the smallest detail, up to what color should be the walls in each of the rooms.
Genes contain all the necessary information… But control the process of realization of this information is not genes, but hormones. Genes are blueprints and designs, and hormones are foremen.
Everything is painted, everything is counted, deadlines are defined. Construction began. Hurrah-Ah-Ah!!! Ten months on that wasteland will grow sixteen-house!
Experienced builders, having read to this place, condescendingly smile. In ten months – Aha! Sixteen-story – well! I’ve been there. That’s how the chips fall. It may well happen that in five years on this site will be only a pit under the Foundation and then not fully open.
And they will be absolutely right, these most experienced builders. You never know what can happen. Suddenly the Builder will go bankrupt during construction… Suddenly the next crisis will burst… Suddenly the prices of building materials will sharply increase and the number of floors should be reduced to ten… And can happen and so that the Builder will offer to build not sixteen-storey, and forty-storey house and means for this purpose will provide…
The same thing happens in the body. Let us assume that the genetic program of a person has a maximum height of 180 cm, which he must reach by the age of eighteen. But if at some point, for some reason, the pituitary gland suddenly increases the production of growth hormone somatotropin, then by the age of eighteen real growth will significantly exceed the growth of “genetic”, planned. There are cases when the growth exceeded the mark of 250 cm! The tallest man in history, who got into the Guinness Book of records – an American Robert Wadlow, who lived in the first half of the XX century. His height was 272 cm! But Wadlow is considered the highest from the official point of view. The growth of Fyodor Makhnov, born in 1878 in Vitebsk province, was equal to 285 centimeters! But due to the fact that makhnov’s growth was not recorded in strict accordance with the rules established for candidates, Makhnov did not get into the Guinness Book.
Now let’s compare the values. Microscopic endocrine gland – the pituitary gland, weighing less than a gram, produces a hormone, the content of which in the blood normally ranges from 1 to 5 ng/ml. Ng/ml – a nanogram per milliliter or one billion grams per one thousandth of a liter. If we recall that the average blood volume in an adult is approximately 4.5 liters, it can be calculated that the body of an adult normally contains from 0.0000045 g to 0.0000225 g of somatotropin [2]. Insignificant, frankly, the number! And their changes, which lead to gigantism or dwarfism, are also insignificant. We are talking about numbers with three or four, or even five zeros after the decimal point. It is hard to believe that some (and I want to write “unhappy”) millionths of a gram produced in excess of the norm, can lead to the fact that a person grows up a meter above the genetically programmed growth. Or it does not grow to about a meter to the genetic bar, if somatotropin is produced by millions of grams less.
The cause of microscopic and macroscopic results!
With hormones always so. Their numbers are insignificant, and the consequences of the fluctuation of these insignificant quantities are enormous!
As on-your, 40 g (forty grams!) is it a large number? “Of course not!”you will say and be absolutely right. What is forty grams? Change! If you translate into sugar, you get two tablespoons, though – with a slide. And by the way, about this amount of adrenaline contained in the blood of the entire population of our planet. The entire population, which will soon pass for seven and a half billion! Here’s how!
A small clarification – hormones do not change the genetic program. They correct its execution.
Many readers, especially those who are familiar with the basics of genetics and the principles of evolution, may have a natural and relevant question – why? Why do you need to adjust the execution of the program, which was formed during the adaptation of the body to the conditions of the environment? Survive and produce offspring, the most adapted individuals. Their features are “polished” in the process of natural selection, and the result is a kind of optimal genetic program, a set of features, having which the body can comfortably or relatively comfortably exist in specific conditions. Why you need to get involved in this program? Why do you need to arrange an additional system of regulation – endocrine? The best is the enemy of the good, and the superfluous is the enemy doubly, is not it? And what is the use of growth in 280 cm or 80 cm? Where, in General, logic and reason? After all, it is believed that in nature everything is arranged reasonably.
Giants and dwarfs are, of course, extremes. And additional endocrine regulation of execution of the program put in genes is necessary unambiguously. Hormonal regulation is not a whim of nature, but a reasonable safety mechanism that allows a particular organism to adapt to permanently changing environmental conditions. In addition, during life in the body may be certain changes. That is, the set of genes, the program may need modifications. That’s in the body and arranged in a complex multi-step regulation of processes of life. With various hedges.
But back to our somatotropin, growth hormone, hormone-Builder.
Everyone probably heard the belief that people grow up during sleep. Not so it and groundless, this belief. The production of somatotropin, as well as many other hormones, is not continuous, but periodic. Periods of increase alternate with periods of decline and the highest peak of somatotropin production is observed at night, one to two hours after falling asleep. So we really grow up in a dream. Men grow up to the age of twenty and women grow up to the age of eighteen.
Increased production of somatotropin at an early age leads to gigantism, and in adults – to a disease called acromegaly. The name comes from the Greek words “ACROS” – limb and “Megas” – large, because with this disease grow – expand and thicken the bones of the skull (especially – the front part), hands, feet. But the bones of the limbs and spine in adults no longer grow, no matter how much somatotropin they “water”, because the so-called “growth zones” – areas of intense cell division, in adulthood are reborn, ossify.
There is a natural question – why do we need somatotropin in adulthood? What’s the use of growth hormone if we’re not already growing? Why the pituitary continues to produce it. Readers, a little versed in endocrinology (and in the first place – women with children), can give an example of such a process as lactation, milk production by the mammary glands. While the milk is needed for feeding, it is produced intensively. After the woman ceases to apply the child to the breast, milk production begins to decline and eventually completely stops. Unnecessary.
About lactation we will talk separately, but in General an example is suitable. Our body does not produce anything superfluous, unnecessary. Why waste energy and materials to produce something that cannot be used?
The fact is that somatotropin is not one, but many professions. Growth hormone it was called for the ability to stimulate growth, but this effect of somatotropin on the body is not exhausted.
Somatotropin stimulates the formation of proteins (anabolic action) and inhibits their decay (anti-catabolic action) [4].
Somatotropin stimulates the breakdown (combustion) of fats in the body.
Now tell me, please, who will really need a substance that stimulates the formation of proteins and fat combustion?
If you find it difficult to answer, then here’s the same question in a simpler form – what happens as a result of stimulation of protein formation and fat combustion?
There’s more protein in the body and less fat, right?
And in what form will accumulate in the body proteins? After all, the body can not store them for future use, just as stores fat. Fats are the only form of unused energy available to our bodies.
In muscles they will accumulate! More precisely, do not accumulate, and used to increase the size of muscle fibers. Note the words “fiber magnification.” With regular training muscles increase in volume and weight by increasing the volume and weight of their constituent fibers, and not due to the formation of new fibers! How many muscle fibers were formed in the process of intrauterine (embryonic) development, so much for life and will remain.
Muscles grow, fat reserves decrease… It’s the dream of any person who wants to have a slim “pumped” body! Regular use of somatotropin helps bodybuilders gain at least 2 kg of muscle mass per month.
Three necessary clarifications.
The first – an intensive build-up of muscle mass occurs with regular training on the background of taking somatotropin.
The second – what was just said, in any case is not a recommendation for the reception of somatotropin for the purpose of intensive muscle building and reducing fat deposits.
ANY DRUG IN ANY CASE FOR ANY PURPOSE SHALL BE MADE BY THE APPOINTMENT OR APPROVAL OF A PHYSICIAN! Write this phrase on a piece of paper, hang it in a prominent place and read it whenever you want to take any drug without consulting a doctor.
The third – in 1989 somatotropin was ranked by the International Olympic Committee to the category of doping. Nowadays, the use of somatotropin by athletes is prohibited almost all over the world.
Stimulation of muscle fiber growth – logically conditioned, so to speak, the function of somatotropin. After all, the muscles must keep up with the growing skeleton, grow at about the same speed as the bones. Somatotropin also stimulates the growth of internal organs.
And somatotropin causes a marked increase in the level of glucose in the blood. This is done by inhibiting the absorption of glucose in adipose tissue, muscle and liver. That is, somatotropin helps to maintain blood glucose at a certain level, provides constancy, participates in the process of self-regulation or homeostasis.
Thus, somatotropin is not only a “Builder”, which increases the growth of the body, but also an “engineer”, regulating the processes of metabolism or, in scientific terms – metabolism. “Engineering” function of somatotropin is also expressed in stimulation of calcium absorption by bone tissue [6]. Calcium gives bones strength, so somatotropin makes bones stronger. And for participation in the processes of homeostasis (maintaining a normal level of glucose in the blood) somatotropin can be attributed to the “conservative hormones”, supporters of the inviolability of the primordial foundations.
But that’s not all. Our “multi-faceted”, more precisely – “multi-talented” somatotropin has another profession, not as a hormone, but as a protein. From a chemical point of view, somatotropin is a protein, because it consists of residues of different amino acids [7]. As an intermediary capable of changing the permeability of cell membranes to certain ions, somatotropin is involved in the regulation of the Central nervous system. Somatotropin molecules interact with certain receptors of the cell membrane and as a result opens a channel for the penetration of certain ions into the nerve cell. So our somatotropin is also a guide.
In 1990, somatotropin suddenly became famous when a group of American scientists published in the journal “The New England Journal of Medicine” an article on the results of monitoring a dozen elderly patients who for six months the hormone was injected into the blood. The article suggested (assumption, nothing more!) that somatotropin is able to slow down aging and improve the physical condition of the elderly. The assumption was picked up by sensationalist journalists and presented to the public as a proven fact. Newspaper headlines screamed that finally found a rejuvenating remedy. Those who fell for this bait, later experienced disappointment because the assumption was not confirmed. To date, the only anti-aging agent, the effectiveness of which is confirmed by a number of folk sources, remain rejuvenating apples.
The production of somatotropin begins after the seventh week of intrauterine (embryonic) development, reaches a peak by the age of six months, and then decreases slightly. If the level of somatotropin in the blood of a six-month-old embryo is about 100 times higher than the maternal figure, by the time of birth this difference is reduced to about 40. It would seem that with such high levels of growth hormone the embryo needs to grow megasuperstar, but in reality this is not happening. The reason is that somatotropin has very little effect on the growth of the embryo. The blood contains a lot of it, but the receptors that can interact with it, are still in immature form. The hormone necessarily needs a receptor with which it can interact. A hormone without a receptor is not a hormone, but simply a chemical contained in the blood.
In the embryonic period and during the first year of life, thyroid hormone (or thyroid hormone) triiodothyronine is of great importance for growth. Here’s another Builder hormone for you. An interesting nuance – triiodothyronine is able to accelerate growth only in the presence of somatotropin. If the level of somatotropin for some reason decreases, then triiodothyronine seems to be “out of business”.
Starting from the second year of life, somatotropin becomes the main growth hormone, the main “hormone-Builder”. But from time to time to help him come other hormones. For example, the growth jump in the period from 5 to 7 years is due to the additional influence of sex hormones produced in the adrenal glands, the level of which increases significantly during this period. In the puberty period, the growth rate increases again under the influence of sex hormones, which increase the production of somatotropin approximately 3 times. Thus, sex hormones – estrogens and androgens – can also be considered “hormones-builders”. Estrogens stimulate the production of somatotropin “directly” through exposure to the pituitary gland, and androgens indirectly. There is no need to delve deeper into this topic. It is better to talk about how the hypothalamus, the Supreme Commander of the endocrine system, can affect the production of somatotropin in the pituitary gland.
And it affects through somatoliberin, a hormone that stimulates the production of not only somatotropin, but also another hormone – prolactin. Somatoliberin refers to liberins (“liberators”) or releasing hormones that stimulate the production of hormones in the pituitary gland. Somatoliberin has an antagonist – the hormone somatostatin, also produced by the hypothalamus. Somatostatin inhibits (“inhibits”) the production of growth hormone in the pituitary gland, and therefore it is in our informal, but quite convenient classification refers to “hormones-brakes.” But also, along with somatoliberin, and to “hormone Directors”, that is, to such hormones that regulate the production of other hormones.
We will mention the “hormones-Directors” in the course of our conversation, and the penultimate Chapter will devote them entirely. Not for adulation (same Director!), but because they deserve it.
Summary
The growth of our body regulates (stimulates) the hormone somatotropin, which is produced by the pituitary gland. The most intensive production of somatotropin occurs during the growth of the body, then it decreases, but does not stop at all.
In addition to growth stimulation, somatotropin performs the following functions:
– stimulates the formation of proteins (anabolic action) and inhibits their decay (anti-catabolic action);
– stimulates the breakdown (burning) of fat;
– inhibits the absorption of glucose in adipose tissue, muscles and liver, thereby contributing to the maintenance of blood glucose at a certain level;
– stimulates the absorption of calcium by bone tissue;
– not as a hormone, but as a protein capable of changing the permeability of cell membranes for certain ions, somatotropin is involved in the regulation of the Central nervous system.
Excessive secretion of growth hormone during the growth period leads to gigantism, and in adults, to acromegaly. With a lack of somatotropin during the growth period, dwarfism (nanism) develops.
The activity of the pituitary gland is controlled by the hypothalamus. Hormone somatoliberin hypothalamus stimulates the production of growth hormone, as the hormone somatostatin – inhibits.
In the embryonic period and during the first year of life, the thyroid hormone triiodothyronine is of great importance for growth, which is able to accelerate growth only in the presence of somatotropin. If the level of somatotropin for some reason decreases, then triiodothyronine seems to be “out of business”. Starting from the second year of life somatotropin becomes the main growth hormone, but from time to time to help him come other hormones – sex (estrogens and androgens).