Adrenal gland

Function

Each adrenal is two glands stacked as one: the cortex (steroid factory) wraps the medulla (a sympathetic ganglion gone endocrine). The cortex's three zones echo its products — glomerulosa (aldosterone for salt), fasciculata (cortisol for stress and glucose), reticularis (androgens, including DHEA).

The medulla's chromaffin cells are modified postganglionic neurons without axons; instead of neurotransmitters released at synapses, they pour adrenaline and noradrenaline into the blood — the body's hormonal alarm siren wired directly to the sympathetic system. The left gland rides the kidney's medial apex, sharing venous drainage into the left renal vein.

Blood supply

Superior (inferior phrenic), middle (aorta) and inferior (renal) suprarenal arteries.

Nerve supply

Preganglionic sympathetic fibres (T5–T11) synapse directly on medullary chromaffin cells.

Clinical relevance

Addison disease

Autoimmune adrenal cortical failure — fatigue, pigmentation, salt craving, hypotension; a cortisol crisis kills under stress.

Phaeochromocytoma

A medullary catecholamine tumour — episodic headache, sweating and palpitations with paroxysmal hypertension; the old '10% rule' underestimates heritable cases (now ~30–40%).

Related conditions

• Cushing's syndrome
• Addison's disease (adrenal insufficiency)