Cortisol belongs to a class of hormones called glucocorticoids, which affect almost every organ and tissue in the body. Cortisol’s most important job is to help the body respond to stress. Among its many vital tasks, cortisol helps
•maintain blood pressure and cardiovascular function
•slow the immune system’s inflammatory response
•maintain levels of glucose—a form of sugar used for energy—in the blood
•regulate the metabolism of proteins, carbohydrates, and fats
The amount of cortisol produced by the adrenals is precisely balanced. Like many other hormones, cortisol is regulated by the brain’s hypothalamus and the pituitary gland. First, the hypothalamus releases a “trigger” hormone called corticotropin-releasing hormone (CRH) that signals the pituitary gland. The pituitary responds by sending out ACTH, which in turn stimulates the adrenal glands. The adrenal glands respond by producing cortisol. Completing the cycle, cortisol then signals back to both the pituitary and hypothalamus to decrease these trigger hormones.