3.3.1.2. The Adrenal Glands

13_28The 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:

  • Boost the supply of oxygen and glucose to the brain and muscles (by increasing heart rate and stroke volume,vasodilation, increasing catalysis of glycogen in liver, breakdown of lipids in fat cells)
  • Dilate the pupils
  • Suppress non-emergency bodily processes (e.g., digestion)
Noradrenaline (norepinephrine) Chromaffin cells Fight-or-flight response:

  • Boost the supply of oxygen and glucose to the brain and muscles (by increasing heart rate and stroke volume,vasoconstriction and increased blood pressure, breakdown of lipids in fat cells)
  • Increase skeletal muscle readiness.
Dopamine Chromaffin cells Increase heart rate and blood pressure
Enkephalin Chromaffin cells Regulate pain

adrenalglandsandstress

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