(ORDO NEWS) — What are hormones, how do they differ from other molecules of the body and how are they associated with rare diseases.
Hormones are biologically active substances that transmit information from organ to organ. They are responsible for sleep, sexual desire, need for food and other processes in the body. But to say how many different hormones should be in the body is impossible.
The concept of norm in this case is individual and depends on many factors. About what role hormones play in our lives and what they are, tells biologist Olga Smirnova in the framework of the guide “Hormones”.
Why are hormones needed?
Hormones are responsible for key body processes: metabolism, growth and development, sexual function and reproduction, pulse rate, blood pressure, appetite, sleep and wake cycles, body temperature, and many others.
Hormones are synthesized in the cells of the endocrine glands and tissues of certain organs, for example, in the heart or stomach. Such hormones also control the state of the tissue in which they formed. For example, leptin is synthesized in adipose tissue and is responsible for suppressing appetite, and its deficiency leads to obesity.
Lack of hormones, as a rule, turns into deplorable, and in some cases irreversible, consequences. For example, with a lack of growth hormone secreted by the pituitary gland, the child remains a dwarf. And insulin deficiency is associated with diabetes.
How are hormones different from other substances?
Hormones are signaling compounds. Unlike nerve cells – transmitters of the nervous system – hormones do not use electrical impulses to exchange information, but are sent to the recipient. If we compare these two types of carriers, we can say that hormones are part of the wireless connection through the bloodstream, and each hormone binds to cells, tissues and organs in different ways.
The number of hormones in the human body is small, and they themselves are strictly specific: each hormone performs only its function. This is due to the characteristics of the “receivers” – cell receptors, where hormones must enter. Each type of cell has a specific type of receptor, with the help of which recipient cells “receive and decrypt information” received from the hormone. This process in general resembles a key and lock mechanism.
For example, adrenaline interacts with certain proteins – adrenaline receptors. They are classified as transmembrane proteins that are coupled to a G-protein, an intermediary protein that transmits signals from receptors to cell membrane enzymes. Only 10–20% of known drugs can interact with them.
This indicates the exclusive and exclusive role of adrenaline receptors. For the study of the mechanism of adrenaline in 2012, scientists from Duke University and Stanford University received the Nobel Prize in chemistry.
If the receptors are inside the cell, then they interact with hormones that regulate the function of the gene (some steroids and thyroid hormone), and if the receptors are on the surface of the cells, then the action of their hormones is directed to the protein and RNA molecules or ion channels of the cells.
What are hormones like?
Hormones are divided into several classes: protein-peptide hormones, steroids that are formed from cholesterol, and hormones – derivatives of amino acids.
Hormones from amino acids use tyrosine for their synthesis. Its variety – L-tyrosine – is part of all the proteins of living organisms. And in the adrenal glands and thyroid gland with the help of tyrosine, adrenaline, norepinephrine and thyroxine are formed.
Protein-peptide hormones are hormones that consist of amino acid residues connected by peptide bonds and are encoded directly by DNA. Protein-peptide hormones are synthesized from biologically inactive prohormones, or precursor substances. So, for example, insulin is formed from preproinsulin: preproinsulin loses 23 amino acid residues from its structure and becomes proinsulin, and losing another 34 – insulin.
The most famous representatives of protein-peptide hormones are insulin, which maintains a certain level of glucose in the blood and, if necessary, reduces it; glucagon, which raises the level of glucose in the blood; and growth hormone – it is responsible for skeletal growth and weight gain.
The basis of steroid hormones is cholesterol. It and its derivatives do not dissolve in water, so steroid hormones easily penetrate target cells through the bloodstream. They are produced in the adrenal cortex, testes, ovaries and placenta, that is, the hormones of the adrenal cortex and genital are referred to steroid hormones.
About 30 types of hormones, corticoids, are formed in the adrenal cortex. They are divided into three groups. The first is glucocorticoids. Their task is to regulate carbohydrate metabolism, provide anti-inflammatory and anti-allergic effects. The second group is mineralocorticoids, which are responsible for the water-salt balance in the body. And the hormones of the third group are inactive androgens.
As for sex hormones, they differ: in women these are estrogens, in men – androgens. The task of the latter is the growth, maturation, functioning of the reproductive system and the formation of secondary sexual characteristics. The task of estrogen is sexual arousal, the ability to endure and nourish a child and perform other functions of the female reproductive system.
What happens during hormonal disruptions?
Impaired hormone production leads to very specific consequences. For example, with an excess of cortisol, a hormone associated with stress and metabolic regulation, Cushing’s disease can develop. With the disease, obesity and muscle atrophy occur. In addition, a mustache or a beard begins to grow in women – this is due to the increased production of other hormones.
The concomitant effects of Cushing’s disease are bone fragility up to osteoporosis, impaired insulin sensitivity and, as a consequence, the development of diabetes.
Another example is hypothyroidism, that is, insufficient production of hormones, and hyperthyroidism is their overabundance. In the first case, anemia, cold intolerance, bradycardia, depression, brittle nails and brittle bones, puffiness of the body and other symptoms can occur.
For children, this disease is dangerously high risk of developing cretinism. Hyperthyroidism (excessive thyroid function) is associated with tachycardia, heat intolerance, increased appetite, accelerated metabolism, and, as a result, excessive thinness and exophthalmos (exfoliation).
Why is the hormonal norm relative?
It is widely believed that there is a certain hormonal background – the rate of hormone production, but this is not so. Each person has an individual ratio of the number of hormones at a certain age and under certain circumstances.
Have you heard the expression: “Children grow up in a dream”? It illustrates the fact that hormones can be produced in different quantities at different times of the day. In children, growth hormone is produced at night much more intensively than during the day. Therefore, talking about the hormonal background can only be in the context of the “here and now” and this particular person.
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