Hormones of the Adrenal Glands

The adrenal cortex produces over two dozen corticosteroid hormones across three zones. The zona glomerulosa produces mineralocorticoids like aldosterone, regulating electrolyte balance. The zona fasciculata produces glucocorticoids such as cortisol and corticosterone, which accelerate glucose synthesis in the liver and promote glycogen formation in muscle and adipose tissue. The zona fasciculata also produces smaller amounts of androgens.

Glucocorticoids speed up glucose synthesis in the liver while promoting glycogen formation in muscle and adipose tissue. This dual action ensures glucose availability during stress or fasting. The name glucocorticoids reflects their primary impact on glucose metabolism, making them essential for maintaining blood glucose levels and supporting energy production across the body.

In adolescents, adrenal androgens stimulate the development of pubic hair during puberty. In adult women, these hormones promote muscle mass development, support blood cell formation, and enhance sex drive. Although produced in smaller amounts compared to other adrenal hormones, androgens contribute significantly to secondary sexual characteristics and metabolic functions throughout life.

The adrenal medulla contains chromaffin cells that secrete catecholamines—epinephrine and norepinephrine—in response to stress. These hormones promote strength and endurance in skeletal muscles and break down stored fat and glycogen in adipose tissue and the liver. Continuously packaged in vesicles and released at low levels through exocytosis, catecholamines provide rapid energy mobilization during heightened demands.

The adrenal medulla contains two distinct types of chromaffin cells: one produces epinephrine and the other produces norepinephrine. Both catecholamines are continuously stored in vesicles and released at low levels by exocytosis in response to stress. While structurally similar, these hormones work together to enhance muscle performance and mobilize energy reserves during the body's stress response.

Aldosterone is a mineralocorticoid produced by the zona glomerulosa of the adrenal cortex. It regulates the electrolyte composition of body fluids by controlling sodium and potassium levels. This hormone is crucial for maintaining proper fluid balance, blood pressure, and cellular function throughout the body.

Catecholamines from the adrenal medulla are continuously packaged in vesicles and released at low baseline levels through exocytosis. Stress triggers increased secretion of these hormones. Corticosteroids from the adrenal cortex are also regulated by stress signals and maintain steady-state levels to support electrolyte balance and glucose metabolism throughout the day.