The adrenal glands, located on top of each kidney, are responsible for secreting hormones necessary for regulating bodily functions. The outer part of the adrenal glands, known as the adrenal cortex, secrete hormones that affect metabolism such as cortisol; hormones essential to the immune system such as corticosterone; hormones that affect blood pressure and cardiovascular functions such as aldosterone; and sexual hormones. The medulla, the inner portion of the gland, secretes hormones essential to regulating stress responses including epinephrine and norepinephrine.
Blood Pressure Regulation
The adrenal glands secrete several hormones that affect blood pressure, including cortisol, aldosterone, epinephrine and norepinephrine. The presence of cortisol makes blood vessels more sensitive to the effects of epinephrine and norepinephrine, which trigger blood vessels to constrict. If cortisol levels become low, blood vessels dilate and blood pressure drops.
Aldosterone, a hormone released by the adrenal cortex, is responsible for regulating the levels of sodium and potassium in the blood. Aldosterone triggers the body to reabsorb sodium and secrete potassium which in turn keeps the fluid levels constant and maintains blood pressure.
Blood Glucose Regulation
Cortisol is important in regulating blood sugar (glucose) levels. Blood glucose levels rise after eating, which triggers the pancreas to release insulin to bring glucose levels back down. Insulin, however, makes glucose levels fall too fast and too far, so cortisol brings the sugar levels back to normal. This action of cortisol helps the body's metabolism remain constant and helps in weight regulation.
Sexual Hormone Production
The adrenal glands produce some male androgen hormones and female estrogen hormones. Although the sexual organs, the testes and ovaries, are the primary producers of the hormones, production levels drop once menopause or andropause (middle age for men) are reached. The adrenals then pick up the slack by continuing to produce the sex hormones and helping to maintain sexual function and libido (desire).
Maintain Energy Levels
Cortisol is important for keeping energy levels up. Between meals, cortisol signals the proteins in muscles to break down and release amino acids, which the body then converts to glucose, the main source of energy for the body.
Stress Response
The adrenal glands produce and release the two most important stress hormones, epinephrine and norepinephrine. When the body is confronted with a stressful situation, the adrenal glands release these hormones as part of the "fight or flight" response. The hormones increase blood pressure, heart rate and respiratory rate, which sharpen the senses and allow the body to be focused to get us through a difficult situation.
Immunity Enhancer
The corticosteroids secreted by the adrenal glands, including cortisol, have an anti-inflammatory and anti-oxidant effect on the body. These hormones help the body to deal with allergic reactions as well as to fight off infections.
