Anatomy and Physiology Resource Site

9.6 - Adrenal Gland

The adrenal glands are found resting on top of the kidneys, forming a cone-shaped structure on the superior part of the kidneys.

Each adrenal gland has two major layers: the superficial cortex and the medulla, which makes up the internal space of the adrenal gland.

Within the adrenal cortex there are three layers that secrete different types of hormones: mineralocorticoids, glucocorticoids and sex hormones.

Adrenal cortex: Mineralocorticoids

Major hormone: Aldosterone
Target organ: Kidney tubules
Function: Regulate blood salt and water balance
Effect: Reabsorption of Na+ and water and secretion of K+ in kidney tubules
Regulation: Humoral (Blood Na+ and K+ concentrations)
Secretion stimulated by: High salt/low water in the blood; renin-angiotensin system
Secretion inhibited by: atrial natriuretic peptide (ANP)

Adrenal cortex: Glucocorticoids

Major hormones: Cortisone and cortisol
Target tissue: All body cells
Function: Regulation of normal cell metabolism and energy molecules
Effect: Increase in blood glucose levels by fat breakdown, inhibition of prostaglandins, decreases edema
Regulation: Hormonal (ACTH levels)

Adrenal cortex: Sex hormones

Major hormones: Androgens, estrogens (very little)
Function: Secondary sex characteristics; only androgen secreted in females is produced here (DHEA) - responsible for the sex drive
Regulation: Hormonal (ACTH levels)

Adrenal medulla: Catecholamines

Major hormones: Epinephrine (adrenaline) and norepinephrine (noradrenaline)
Target: Blood stream
Function: Enhance sympathetic tone
Effect: Increased heart rate, blood pressure (through vasoconstriction), blood glucose; bronchodilation
Regulation: Sympathetic division of the ANS

Click here for an digital activity on the hormones of the adrenal gland