Biochemistry

change in the macrostructure of membrane proteins and an increase in its permeability. Due to this, insulin affects the speed and direction of enzymatic processes. It enhances the penetration of glucose into muscle cells, contributing to the formation of glycogen. Under the influence of insulin, the rate of glucose uptake by adipose tissue cells increases, which promotes lipogenesis and prevents lipolysis. With a deficiency of insulin, the flow of glucose into the corresponding tissues slows down, which leads to a violation of its metabolism. Insulin mainly enhances the reactions of biosynthesis, i.e., anabolism, which is why it is called the hormone-anabolizer . Under the influence of insulin, the use of oxidation energy for phosphorylation processes is improved. Therefore, it affects the biosynthesis of macroergic compounds. In this regard, insulin is also called "conjugating hormone." With insufficient insulin secretion, diabetes develops . In this disease, characteristic metabolic disorders are observed: blood sugar levels increase (hyperglycemia), urine sugar appears (glucosuria), glycogen breakdown in the liver and muscles increases, protein and fat biosynthesis slows down, and the rate of glucose oxidation in tissues decreases. In addition, a negative nitrogen balance is noted , cholesterol levels in the blood increase, fat mobilization from “ fat depots ” increases, carbohydrates from amino acids are synthesized and acetone bodies are formed. Glucagon is synthesized by the а -cells of the islets of Langerhans in the pancreas. It helps increase blood glucose. This action is explained by the fact that glucagon stimulates the conversion of inactive liver phosphorylase to active. As a result, the breakdown of glycogen in this organ is enhanced, which becomes the reason for the increase in the glucose content (in the form of glucose-1-phosphate) in the blood, while the glycogen supply in the liver decreases. Steroid hormones. This group includes hormones - derivatives of steroids. They are synthesized in the adrenal cortex , testes, ovaries, placenta . Steroid hormone molecules are able to penetrate into the cell and interact with specific receptors in its cytoplasm. As a result, a hormone-receptor complex is formed, which, entering the cell nucleus, affects its genetic apparatus. The hormones of the adrenal cortex are produced by over forty. They are collectively called corticosteroids. Steroid hormones are lipid compounds. Their precursor is cholesterol (cholesterol). According to their function, the hormones of the cortical substance of the adrenal glands are conditionally divided into two groups: mineralocorticoids (aldosterone and deoxycorticosterone), which regulate water-salt metabolism and glucocorticoids (cortisone, cortisol, etc.), which stimulate the synthesis of glucose from amino acids and fats (gluconeogenesis) and promote deposition glycogen in the liver. 286