Cortisol belongs to a class of hormones called glucocorticoids, which affect almost every organ and tissue in the body. Scientists think that cortisol has possibly hundreds of effects in the body. Its most important job is to help the body respond to stress. Among its other vital tasks, cortisol helps:
- Maintain blood pressure and cardiovascular function
- Slow down the immune system's inflammatory response
- Balance the effects of insulin in breaking down sugar for energy
- Regulate the metabolism of proteins, carbohydrates, and fats
- Maintain proper arousal and sense of well-being.
Because cortisol is so vital to health, the amount produced by the adrenals is precisely balanced.
Like many other hormones, cortisol is regulated by the brain's hypothalamus and the pituitary gland, a bean-sized organ at the base of the brain. First, the hypothalamus sends "releasing hormones" to the pituitary gland. The pituitary responds by secreting hormones that regulate growth and thyroid and adrenal function, as well as sex hormones, such as estrogen and testosterone. One of the pituitary's main functions is to secrete ACTH (adrenocorticotropin), a hormone that stimulates the adrenal glands. When the adrenals receive the pituitary's signal in the form of ACTH, they respond by producing cortisol. Completing the cycle, cortisol then signals the pituitary to lower secretion of ACTH.
Aldosterone belongs to a class of hormones called mineralocorticoids, also produced by the adrenal glands. It helps maintain blood pressure and water and salt balance in the body by helping the kidneys retain sodium and excrete potassium. When aldosterone production falls too low, the kidneys are not able to regulate salt and water balance, causing blood volume and blood pressure to drop.