Nadledviny

Nadledviny, or adrenal glands, are two small endocrine glands perched on the upper poles of the kidneys. They form part of the endocrine system and secrete hormones that regulate metabolism, fluid balance, stress responses and blood pressure.

Anatomy: Each nadledvina consists of an outer cortex and an inner medulla. The cortex has three zones: zona glomerulosa (mineralocorticoids, mainly aldosterone), zona fasciculata (glucocorticoids, mainly cortisol) and zona reticularis (androgens). The medulla secretes catecholamines—adrenaline and noradrenaline—in response to sympathetic stimulation.

Function and regulation: Cortisol, aldosterone and catecholamines influence metabolism, electrolyte balance and cardiovascular responses. Cortisol is released in a pulsatile pattern under the control of adrenocorticotropic hormone (ACTH) from the pituitary. Aldosterone secretion is mainly governed by the renin–angiotensin–aldosterone system and plasma potassium. The medullary catecholamines prepare the body for rapid action during stress.

Clinical relevance: Notable disorders include Addison’s disease (adrenal insufficiency), Cushing’s syndrome (excess cortisol), congenital adrenal hyperplasia and pheochromocytoma (catecholamine-secreting tumor). Adrenal disorders can disrupt electrolyte balance, blood pressure and energy metabolism. Diagnosis uses hormonal assays, stimulation tests and imaging; treatment ranges from hormone replacement to tumor removal.

Development and anatomy: The cortex derives from mesoderm, the medulla from neural crest cells. Blood supply comes from the superior, middle and inferior suprarenal arteries, with venous drainage into the renal veins or inferior vena cava.