The body has two triangular adrenal glands, one on top of each kidney. The adrenal glands have two parts, each of which produces a set of hormones and has a different function. The outer part, the adrenal cortex, produces hormones called corticosteroids that influence or regulate salt and water balance in the body, the body’s response to stress, metabolism, the immune system, and sexual development and function.
The inner part, the adrenal medulla, produces catecholamines, such as epinephrine. Also called adrenaline, epinephrine increases blood pressure and heart rate when the body experiences stress. (Epinephrine injections are often used to counteract a severe allergic reaction).
Adrenal Cortex
| Secreted hormone | From cells | Effect |
|---|---|---|
| Glucocorticoids (chiefly cortisol) | zona fasciculata and zona reticularis cells | Stimulates gluconeogenesis
Stimulates fat breakdown in adipose tissue Inhibits protein synthesis Inhibits glucose uptake in muscle and adipose tissue Inhibits immunological responses (immunosuppressive) Inhibits inflammatory responses (anti-inflammatory) |
| Mineralocorticoids (chiefly aldosterone) | Zona glomerulosa cells | Stimulates active sodium reabsorption in kidneys
Stimulates passive water reabsorption in kidneys, thus increasing blood volume and blood pressure Stimulates potassium and H+ secretion into nephron of kidney and subsequent excretion |
| Androgens (including DHEA and testosterone) | Zona fasciculata and Zona reticularis cells | In males: Relatively small effect compared to androgens from testes
In females: masculinizing effects |
Adrenal Medula
| Secreted hormone | From cells | Effect |
|---|---|---|
| Adrenaline (epinephrine) (Primarily) | Chromaffin cells | Fight-or-flight response:
|
| Noradrenaline (norepinephrine) | Chromaffin cells | Fight-or-flight response:
|
| Dopamine | Chromaffin cells | Increase heart rate and blood pressure |
| Enkephalin | Chromaffin cells | Regulate pain |
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