Adrenal physiology

Question 1

Adrenal physiology: Adrenal medulla?

Answer 1

• The chromaffin cells of the adrenal medulla secrete the catecholamines noradrenaline and adrenaline.
• The medulla is innervated by the splanchnic nerves;
• the preganglionic sympathetic fibres secrete acetylcholine causing the chromaffin cells to secrete their contents by exocytosis.
• Phaeochromocytomas are derived from these cells and will secrete both adrenaline and nor adrenaline.

Question 2

Adrenal cortex?

Answer 2

Three histologically distinct zones are recognised:

Zona glomerulosa: Outer zone Aldosterone

Zona fasiculata: Middle zone Glucocorticoids

Zona reticularis: Inner zone Androgens