The thyroid gland and its hormones play a very important role in the work of the whole human body – it participates in the coordination and regulation of the work of all organs. For thyroid hormones, a major role in the transmission of signals, nerve impulses and biological substances is noted. Thyroid  It is especially important for the normal functioning of the human body, since all tissues and cells need its hormones. But people have faced the problem of hormone imbalance since ancient times – the nervous and excitable disposition that was observed in humans with an excess of thyroid hormones was valued in Spain in the 17th century, but calm and graceful slowness were in vogue in Switzerland. The Renaissance appreciated the swollen and swollen neck of women, which was repeatedly noted in the paintings of many classics. But in those days, people did not even suspect that such conditions were caused by iodine deficiency.

Thyroid structure

This organ is also called the thyroid gland. The thyroid gland in shape resembles a butterfly or horseshoe, it consists of three main parts: two lateral lobes and the isthmus. Each of the three parts has another unstable segment – pyramidal. The size of the thyroid gland depends on many factors and can vary even in the same person. The structure of the thyroid gland is quite complex – it consists of many bubbles – follicles, on the edges of which there are cells – thyrocytes, and inside each follicle there is a colloid – a thick, watery liquid. Thyrocytes synthesize hormones, which then accumulate in the colloid and, if necessary, slowly enter the human blood.

Thyroid hormones

The main two hormones produced by the thyroid gland are called triiodothyronine – which contains three iodine molecules and tetraiodothyronine or thyroxine – containing four iodine molecules. Abbreviated as these hormones are designated as T3 and T4. In the human body, the hormone T4 is gradually synthesized into the hormone T3. T3 is the main biologically active hormone that affects metabolism.

In order for the thyroid gland to produce these hormones, it requires two essential components – iodine and the amino acid tyrosine. Without iodine entering the body, hormone production completely stops, which is why it is very important to prevent iodine deficiency in food. In addition, iodine is responsible not only for the formation of hormones by the thyroid gland, but also responsible for the production of adrenaline, dopamine and melanin.

How are thyroid hormones formed?

The synthesis of thyroid hormones can be divided into four stages:

1. Thyroid absorption of iodine – its concentration in the gland exceeds the concentration in the blood by 30-40 times.
2. Activation of iodine, due to which iodine molecules bind to tyrosine amino acid molecules.
3. Condensation with the formation of hormones T3 and T4, as well as their accumulation in the form of a colloid.
4. The secretion of the hormones T3 and T4 into the blood, under the influence of thyroid-stimulating hormone.

Before getting into the blood, thyroid hormones bind to transport proteins so that the kidneys do not wash them out of the body, because they are very small. In the tissues themselves, the hormone T4 turns into T3, which carries out the biological effect of hormones by 90%.

The action of thyroid hormones

It is known that thyroid hormones affect all tissues and cells of the body, as well as the work of each system:

• increase heat generation;
• activate the synthesis of protein required to build new cells;
• responsible for the proper growth and development of the central nervous system, especially in children;
• participate in the formation of red blood cells;
• normalize the development of genital organs and the release of sex hormones;
• strengthen the process of reverse absorption in the intestine, increase the level of glucose in the blood;
• stimulate the breakdown of fats, which contributes to weight loss;
• have an anabolic effect.

Low thyroid hormones

Reduced levels of thyroid hormones in the blood are manifested in humans by the following symptoms:

• weight gain, which does not decrease even with a diet and physical exercise;
• fatigue and general weakness;
• constantly depressed state;
• menstrual irregularities, infertility;
• low body temperature – 35.6-36.3;
• constipation
• swelling of the legs, feet, puffiness of the face;
• dry skin, itching, dandruff;
• decreased heart rate;
• Permafrost, even in a warm room;
• joint and muscle pains;
• memory impairment and reactions.

High blood levels of thyroid hormones

This condition is called hyperthyroidism, characterized by increased thyroid function and is manifested by the following symptoms: 

• weight loss even with good appetite;
• fatigue, general weakness;
• permanent arousal;
• menstrual irregularities, infertility;
• dryness and sagging skin;
• elevated body temperature, sometimes at certain hours;
• tachycardia, high blood pressure;
• memory impairment and reaction rate;
• feeling of heat.