Before talking about which gland produces insulin, you need to determine what it is. Insulin is a member of the "family" of polypeptide hormones, the simplest proteins whose molecular weight is very small. There are two amino acid chains in the insulin molecule: in the short - 21 amino acids, in the long - 30. Between the chains there are bridges of 2 sulfur atoms (they are called - disulfide bridges). Insulin acts on the body by lowering blood sugar levels.
From the history of the issue
What gland produces insulin, preventing the development of a dangerous disease - diabetes? Pancreas If disulfide bridges are broken between insulin chains, most often it will not affect blood sugar, although this does not always happen. This has been repeatedly tested and proven during the study of this important hormone. And the story is very long. It began in 1889 with studies conducted by scientists from Germany - I. Mering and O. Minkowski. At that moment, no one knew which gland produces insulin and what kind of substance it is.
They experimented on dogs and noted that if the pancreas was removed from the experimental animals, the animals developed an irrepressible thirst and, accordingly, huge amounts of urine were released. These phenomena were concomitant in research, but did not go unnoticed. In this clinic, diabetes has been dealt with for a long time, and therefore they noticed that these symptoms also appear in patients. In experimental dogs, diabetes was induced artificially. It was then that assumptions appeared about what insulin is, what gland produces it.
Langerhans Islands
However, so far little has been known about the fullness of the pancreas - one of the most important digestive glands, in addition to the fact that it produces some kind of antidiabetic substance. Thirty years before the studies of Mering and Minkowski, P. Langerhans discovered tiny islands in the thickness of the pancreas, which are called by the name of this German scientist.
Their tissue structure is completely different from the rest, they are completely isolated, even excretory ducts are absent. Perhaps the gland that produces insulin uses the islets of Langerhans for this, this is a logical explanation. And in 1901, L. Sobolev, through his experiments, proved that this is exactly what happens.
It turned out that the islets are not related to digestive function. Even if the rest of the pancreatic tissue stopped functioning, the islets of Langerhans worked - diabetes did not develop. The gland that produces insulin could not influence these parts of its own territory. Since then, this antidiabetic substance has been called insulin ("insula" in Latin means "islet"). At that time no one was able to get insulin, moreover, there was no complete confidence that it even existed.
Insulin production
And only in 1922 in Canada this active hormone was obtained by researchers F. Bunting and C. Best. Even with the complete absence of the pancreas, life could be supported by an artificially created drug, otherwise death would occur in a matter of days.
Previously, diabetes was treated only with a diet, in every way restricting the intake of carbohydrates in the body. Now one could go the other way, and it was a staggering success, since diabetes diagnosed at a young age at that time was a death sentence. It has not been determined why the pancreas stops producing insulin.
Insulin production was immediately established in many countries, and it was inexpensive, it was not labor-intensive. In the 50s, its structural formula was fully studied by the Englishman F. Sanger, and in 1963 the biochemists of Germany and the USA synthesized insulin. It must be said that synthesized insulin is much more expensive than natural insulin obtained in cattle slaughterhouses.
Sugar or glucose
Each endocrine gland is a compact organ, and only the pancreas produces insulin using isolated islets of Langerhans. And there are about a million of them on its territory! Each of them has an area of only about two hundred microns. But no matter how small the islands that produce insulin are, pancreatic cells cannot affect them, although they are different. Insulin is obtained only in beta cells, this hormone is synthesized in them, and, like granules in shape, insulin granules are stored inside.
Blood flows abundantly to the islets, so the sugar content in it is constantly known. If a dangerous increase occurs, the granules rise to the surface of the cell and go outside - into the blood. And again, the gland cells tirelessly produce insulin, how much is currently needed, regulating its output. Only in Russian medicine is the term “blood sugar” rooted, in fact it is glucose.
Insulin Chain Functions
Both long and short chains each play their own special role. It cannot be said that even today all their functions have been studied, only some steps have been taken in this direction. And we don’t know much about insulin yet. It is known which gland produces the hormone insulin, but in what form it is contained in the blood - no. There are only speculations. For example, that part of the hormone is bound by a certain protein, which is probably produced by the liver. Even almost nothing is known about this protein itself, since it is vanishingly small, but its role is very large - it binds insulin reliably.
Usually bound forms function in the body only as a transport. But here everything is different. Protein-bound insulin acts on adipose tissue, but not on muscles. However, there is a lot of fat in the body, and it is not as harmful as they say about it. Adipose tissue can separate insulin from protein and share excess muscle hormones with muscle. Absolutely all tissues that need it can use free insulin, but the key to the binding protein is only fat.
The amount of insulin needed
The body of a healthy person produces about two milligrams of insulin daily. And for patients, this drug, when prescribed, is measured in units, and not in milligrams, in different drugs a different amount of insulin by weight. And it is also necessary to reduce the amount of sugar in the blood individually, only by a certain amount. The body produces about forty units, which is quickly used by all tissues. Checked: labeled insulin leaves almost the entire hour later, only 15% remains in the tissues.
How does the sugar reduction mechanism work? Firstly, the flow of glucose into the blood from the liver is reduced, and secondly, muscle, adipose and other tissues take up glucose intensively. Without insulin, these processes would be insufficient. There is a huge amount of glycogen polysaccharide in the liver, and this supply is constantly updated. A certain amount of glucose is leaving, new reserves appear in the place of the departed. Insulin does not allow glycogen to decay en masse, for this reason glucose output from the liver decreases.
Friends and foes
Any hormone lives a certain time for it, after which it breaks down. Insulin can die prematurely, as it is affected by special enzymes contained in the liver and muscles. In fatty tissues, they are also, but much less. This enzyme does not care what exactly to destroy, any protein will do. And if you give him something else, he will leave insulin and take it.
There, in the liver, there is also an enzyme that breaks down insulin into chains and knows how to recreate this hormone from them. It turns out that the liver is both friend and enemy at the same time: it can destroy, but it can also be preserved by spare parts in order to create and throw it back into the blood again.
What hormones harm insulin
But "from scratch" only the pancreas produces insulin. The thyroid gland can suffer greatly with a disease such as diabetes, but cannot help itself with the production of insulin. This hormone enhances the accumulation of fat and reduces the amount of sugar. However, if sugar is low in the tissues, fatty acids from decaying fat are used instead. Hormones that increase the level of glucose in the blood also increase the breakdown of fat deposits in the tissues, that is, they act as direct enemies of insulin, reducing all its work to zero.
The first enemy of insulin is adrenaline, followed by adrenal hormones, growth hormones and many others. Pancreatic cells that produce insulin do not stand idle. If carbohydrate starvation occurs, the appendage in the brain releases a fat-mobilizing substance, causing fat breakdown and increased tissue consumption of fatty acids.
But despite all the intrigues of the "enemies", insulin, even large concentrations of sugar in the blood, can neutralize and bring its amount to normal. And the "enemies" of insulin act short-sightedly, causing the breakdown of fats, but not preventing the insulin from working: it works endlessly, creating new fat, using even just released fatty acids.
Pancreatic Vulnerability
This most important organ in the body produces pancreatic juice, known to the ancient Greeks. This juice contains all the essential enzymes that work on the digestion of not only carbohydrates, but also proteins and fats in the intestines.
This is the first and foremost duty of the pancreas. And secondly, it produces hormones, including insulin. And the gland that produces the hormone insulin is not thyroid, but the pancreas.
If the pancreatic ducts become clogged (most often gallstone gets in the way), the enzymes do not get out and change their place of work: instead of the intestines, where they are waiting for real food, they literally devour the mother cells, those that created them. This is an inflammation of the pancreas - pancreatitis. He is always painful - both acute and chronic.
Hormones and enzymes
To the question, what does the pancreas produce besides insulin, it is quite possible to answer that literally everything is needed for life, providing the main thing - the body’s nutrition. Each hormone or enzyme operates in its own field, where only he is competent, and no one will do this work for him.
The body only regulates: skillfully uses one hormone, then another, then more enzyme, then less. For example, if you need to quickly mobilize glycogen in the liver, glucagon and adrenaline are used, then glycogen breaks down, increasing blood sugar. What gland does the hormone insulin produce for rapid mobilization? Only the pancreas.
Tissue glucose uptake
Tissues always capture glucose, not all are equally dexterous, of course. In some, it freely enters cells without any insulin. For example, in the liver, cells of the nervous system, in all digestive glands. And other tissues live, as it were, behind a fence that is difficult to overcome with insulin. There is a gate and a small door in them. When there is no insulin, the door opens slightly so that a lot of glucose does not pass. And when this "hero of the day" appears - insulin, the gates swing open.
So far, scientists have not determined what this barrier is, why glucose cannot constantly freely enter cells. But there are a lot of tissues that need insulin: these are absolutely muscles, all adipose tissue, white blood cells, the lens of the eye, and many nerve cells. These are insulin-sensitive tissues. If they capture glucose, then its level in the blood decreases.
Insulin and human well-being
The normal content of glucose (sugar) in the blood should be from 0.07% to 0.1%, and if from the excess of insulin it drops to 0.03%, the nerve cells will begin to starve, because this is their main source of nutrition.
The cerebral cortex reacts first, then other departments join. And when the brain ceases to function normally, the whole body suffers. Convulsions appear, a person loses consciousness.
conclusions
It is noted that in a poorly developed cerebral cortex, a low level of glucose in the blood is more easily tolerated. For example, fish, frogs and other amphibians practically do not feel even a sharp decrease in sugar in the blood.
Newborn children also have a very low level of it, an adult with such indicators would already have a loss of consciousness. However, in a small child, the brain and its cortex are still underdeveloped, and therefore consumes little glucose, and it does not need as much as an adult.
How does insulin help glucose uptake? This, as scientists say, is not a simple process, not diffusion, but fermentation. However, the nature of this process has not yet been fully disclosed, and therefore it is impossible to draw final conclusions. And therefore, the treatment of diabetes is a matter of complexity and purely individual.