Cortisol is a hormone that is formed in the adrenal cortex. It protects the body from stress, regulates blood pressure, participates in the metabolism of proteins, fats and carbohydrates.The release of cortisol is regulated by the adrenocorticotropic hormone (ACTH) produced in the pituitary gland, a small gland located on the lower part of the brain. The concentrations of ACTH and cortisol in the blood are regulated by the feedback method. A decrease in the concentration of cortisol increases the production of ACTH, as a result of which the production of this hormone is stimulated until it returns to normal. An increase in the concentration of cortisol in the blood, on the contrary, leads to a decrease in the producion of ACTH.