Our body can be compared with a metropolis. The cells inhabiting it sometimes live in "families", forming organs, and sometimes, lost among others, they recede (as, for example, cells of the immune system). Some are homebodies and never leave their refuge, others are travelers and do not sit in one place. They are all different, each with its own needs, character and regime. Between the cells are small and large transport routes - blood and lymph vessels. Every second in our body, millions of events occur: someone or something breaks the peaceful life of cells or some of them forget about their duties or, on the contrary, are too zealous. And, as in any megalopolis, in order to maintain order, competent administration is required here. We know that our chief executive is a nervous system. And her right hand is the endocrine system (ES).
In order
ES is one of the most complex and mysterious systems of the body. Complicated because it consists of many glands, each of which can produce from one to dozens of different hormones, and regulates the work of a huge number of organs, including the endocrine glands themselves. Inside the system there is a special hierarchy that allows you to strictly control its operation. Mysteriousness of ES is associated with the complexity of the mechanisms of regulation and composition of hormones. To explore its work, it requires cutting-edge technologies. The role of many hormones is still unclear. And we only guess about the existence of some, although it is not yet possible to determine their composition and the cells that separate them. That is why endocrinology - a science that studies hormones and organs that produce them - is considered one of the most difficult among medical specialties and the most promising. Having understood the exact purpose and mechanisms of the work of certain substances, we can influence the processes taking place in our body. After all, thanks to hormones, we are born, they create a sense of attraction between future parents, determine the time of formation of sex cells and the moment of fertilization. They change our lives, influencing mood and character. Today, we know that the aging processes are also managed by the ES.
Characters...
The organs that make up ES (thyroid gland, adrenal glands, etc.) are groups of cells located in other organs or tissues, and individual cells scattered in different places. The difference between the endocrine glands from others (they are called exocrine glands) is that the former secrete their products - hormones - directly into the blood or lymph. For this they are called glands of internal secretion. And exocrine - in the lumen of this or that organ (for example, the largest exocrine gland - the liver - secretes its secret - bile - into the lumen of the gallbladder and further into the intestine) or outward (example - tear glands). Exocrine glands are called glands of external secretion. Hormones are substances that can act on cells that are sensitive to them (they are called target cells), changing the rate of metabolic processes. The release of hormones directly into the blood gives the EC a huge advantage. To achieve the effect, it takes a few seconds. Hormones go directly to the bloodstream, which serves as a transport and allows very quickly to deliver the right substance to all tissues, unlike a nerve signal that spreads through nerve fibers and, due to their rupture or damage, may not reach their goal. In the case of hormones, this does not happen: liquid blood easily finds workarounds if one or more blood vessels are blocked. To the organs and cells to which the message of the ES is intended, it was received, receptors that perceive a particular hormone are located on them. Feature of the endocrine system is its ability to "feel" the concentration of various hormones and adjust it. And their number depends on the age, gender, time of day and year, age, mental and physical condition of a person and even our habits. So the ES sets the rhythm and speed of our exchange processes.
... and performers
The pituitary gland is the main endocrine organ. It releases hormones that stimulate or inhibit the work of others. But the pituitary gland is not the top of the ES, it only fulfills the role of the manager. Hypothalamus is a higher authority. This is the department of the brain, consisting of clusters of cells that combine the properties of the nervous and endocrine. They excrete substances that regulate the pituitary and endocrine glands. Under the guidance of the hypothalamus, the pituitary gland produces hormones that affect sensitive tissues. So, thyroid-stimulating hormone regulates the thyroid gland, corticotropic - the work of the adrenal cortex. The growth hormone (or growth hormone) does not affect any particular organ. Its effect extends to a variety of tissues and organs. This difference in the action of hormones is caused by the difference in their importance to the body and the number of tasks they provide. The peculiarity of this complex system is the principle of feedback. ES can be called without exaggeration the most democratic. And, although it has "governing" organs (the hypothalamus and pituitary gland), the subordinates also influence the work of the higher glands. In the hypothalamus, the pituitary gland there are receptors that react to the concentration of different hormones in the blood. If it is high, signals from the receptors will block their production at all levels. This is the principle of feedback in action. The thyroid gland received its name for its shape. It covers the neck, surrounding the trachea. The composition of its hormones is iodine, and its lack can lead to irregularities in the work of the body. Hormones of the gland provide a balance between the formation of adipose tissue and the use of stored fat in it. They are necessary for the development of the skeleton and the well-being of bone tissue, and also enhance the action of other hormones (for example, insulin, accelerating the metabolism of carbohydrates). These substances play a critical role in the development of the nervous system. Lack of hormones in the gland in babies leads to underdevelopment of the brain, and later to a decrease in intelligence. Therefore, all newborns are examined for the content of these substances (this test is included in the screening program for newborns). Together with adrenaline, the thyroid hormones affect the work of the heart and regulate blood pressure.
Parathyroid glands
Parathyroid glands are 4 glands located in the thickness of fatty tissue behind the thyroid, which is why they got their name. The glands produce 2 hormones: parathyroid and calcitonin. Both provide the exchange of calcium and phosphorus in the body. Unlike most endocrine glands, the parathyroid function is regulated by fluctuations in the mineral composition of the blood and vitamin D. The pancreas controls the metabolism of carbohydrates in the body, and also participates in digestion and produces enzymes that ensure the breakdown of proteins, fats and carbohydrates. Therefore, it is located in the area of the transition of the stomach into the small intestine. Iron releases 2 hormones: insulin and glucagon. The first reduces the level of sugar in the blood, causing the cells to absorb it more actively and use it. The second, on the contrary, increases the amount of sugar, causing the liver cells and muscle tissue to give it back. The most common disease associated with abnormalities in the pancreas is type 1 diabetes (or insulin-dependent diabetes). It develops because of the destruction of cells that produce insulin, the cells of the immune system. Most children with diabetes have genome features that probably predetermine the development of the disease. But it is triggered most often by an infection or transferred stress. The adrenal glands got their name for the location. A person can not live without the adrenal glands and the hormones that they produce, and these organs are considered vital. In the program of the survey of all newborns, a test for violation of their work is included - the consequences of such problems will be so dangerous. The adrenal glands produce a record number of hormones. The most famous of them is adrenaline. It helps the body to prepare and cope with possible dangers. This hormone causes the heart to beat faster and to pump more blood to the organs of movement (if it is necessary to flee), increases the frequency of breathing to provide the body with oxygen, reduces sensitivity to pain. It increases blood pressure, ensuring maximum blood flow to the brain and other important organs. Norepinephrine also has a similar effect. The second most important hormone of the adrenal glands is cortisol. It is difficult to name any process in the body, to which it would not exert influence. It forces tissues to release stored substances into the blood so that all cells are provided with nutrients. The role of cortisol increases with inflammation. It stimulates the production of protective substances and the work of immune cells necessary to combat inflammation, and if the latter are too active (including against their own cells), cortisol suppresses their zeal. Under stress, it blocks the division of cells, so that the body does not spend energy on this work, and the immune system occupied by putting the order in order would not miss the "defective" samples. The hormone aldosterone regulates the concentration in the body of the basic mineral salts - sodium and potassium. Sex glands are testicles in boys and ovaries in girls. Hormones, which they produce, are able to change metabolic processes. So, testosterone (the main male hormone) helps the growth of muscle tissue, bone system. It increases appetite and makes boys more aggressive. And, although testosterone is considered a male hormone, it is excreted in women, but in less concentration.
To the doctor!
Most often, children who have excess weight and children who seriously lag behind their peers in growth come to the children's endocrinologist. Parents rather pay attention to the fact that the child stands out among peers, and begin to find out the reason. Most other endocrine diseases have no characteristic features, and the problem parents and doctors often find out when the disorder has already seriously altered the work of some organ or the whole organism. Get accustomed to the baby: physique. In young children, the head and trunk relative to the total length of the body will be larger. From 9-10 years the child begins to stretch, and the proportions of his body approach the adults.