Adrenal Gland

What are the adrenal glands?

The adrenal glands are endocrine glands above the kidneys that produce several hormones. Each gland has an outer layer, the cortex, and an inner region, the medulla. The two regions do different jobs.

Adrenal Gland Hormones and Functions

The StatPearls physiology reference distinguishes cortical steroid hormones—glucocorticoids such as cortisol, mineralocorticoids such as aldosterone, and androgen precursors—from the medulla’s catecholamines, epinephrine (adrenaline) and norepinephrine (noradrenaline).

The NIDDK explanation of adrenal hormones describes cortisol’s contributions to metabolism, blood glucose, blood pressure, and inflammation. Aldosterone helps regulate sodium and potassium balance. The medulla’s adrenaline and noradrenaline contribute to the fight-or-flight response. The glands do much more than prepare the body for a threat.

A fight-or-flight example

Imagine stepping into the road and noticing a car coming toward you. As part of the body's coordinated threat response, the adrenal medulla releases catecholamines into the bloodstream. Adrenaline can make the heart beat faster and help make more glucose available for immediate activity. These are some of the physical changes behind the phrase “fight or flight,” described in the StatPearls catecholamine reference. The adrenal glands contribute to the response alongside the nervous system; detecting the threat and coordinating the full response also involve the nervous system.

Regulation

Cortisol production is regulated through signaling involving the hypothalamus, pituitary, and adrenal cortex. These signals help coordinate cortisol production; other adrenal hormones have their own controls and effects.