Anatomy & Physiology of Adrenal glands.pptx

Adrenal glands

1. SUPRARENAL GLANDS Introduction: The suprarenal glands are a pair of important endocrine glands situated on the posterior abdominal wall over the upper pole of the kidneys behind the peritoneum .

2. They are made up of two parts: ( a) An outer cortex which secretes a number of steroid hormones; and ( b) an inner medulla which secretes adrenalin and nonadrenalin or catecholamines.

3. Location: Each gland lies in the epigastrium, at the upper pole of the kidney, in front of the diaphragm, opposite the vertebral end of the 11th intercostal space and the 12th rib.

4.   Size , Shape and Weight: Each gland measures 50 mm in height, 30 mm in breadth and 10 mm in thickness. It is approximately one-third of the kidney at birth and about one-thirtieth of it in adults. It weighs about 5 gm.

5. Right Suprarenal Gland The right suprarenal gland is triangular to pyramidal in shape. It has ( 1) an apex; ( 2) a base; ( 3) two surfaces; anterior and posterior; and ( 4) three borders; anterior, medial and lateral.

6. Left Suprarenal Gland The left gland is semilunar. It has: ( 1) Two ends, upper, narrow end and lower, rounded end; ( 2) two borders, medial convex and lateral concave and (3) two surfaces: anterior and posterior

7. Arterial Supply: Each gland is supplied by: (1) The superior suprarenal artery, a branch of the inferior phrenic artery; (2) The middle suprarenal artery, a branch of the abdominal aorta; and (3) The inferior suprarenal artery, a branch of the renal artery. Venous Drainage: The right suprarenal vein drains into the inferior vena cava, and the left suprarenal vein into the left renal vein .

8. Physiology of Suprarenal gland : Adrenal cortex The adrenal cortex produces three groups of steroid hormones from cholesterol. They are collectively called adrenocorticocoids (corticosteroids, corticoids). They are: • Glucocorticoids • Mineralocorticoids • Sex hormones (androgens).

9. Adrenal medulla The medulla is completely surrounded by the cortex. It produce the hormones adrenaline and nor adrenaline.

10. Glucocorticoids Cortisol (hydrocortisone), corticosterone and cortisone are the main glucocorticoids. They are essential for life, regu - lating metabolism and responses to stress. Glucocorticoids have widespread effects and these include: • Gluconeogenesis • Lipolysis • stimulating breakdown of protein, releasing amino acids • promoting absorption of sodium and water from renal tubules (a weak mineralocorticoids effect).

11. Mineralocorticoids (aldosterone) Aldosterone is the main mineralocorticoid. Its functions are associated with the maintenance of water and electrolyte balance in the body . It stimulates the reabsorption of sodium (Na+) by the renal tubules and excretion of potassium (K+) in the urine. The blood potassium level regulates the amount of aldosterone produced by the adrenal cortex.

12. Sex hormones Their role is unclear but it is thought that they contribute to the onset of puberty. An elevated level in females causes masculinisation. Control of secretion is poorly understood.

13. Adrenaline and noradrenaline: • increasing heart rate • increasing blood pressure • diverting blood to essential organs including the heart, brain and skeletal muscles by dilating their blood vessels and constricting those of less essential organs, such as the skin • increasing metabolic rate • dilating the pupils . Adrenaline has a greater effect on the heart and metabolic processes whereas noradrenaline has more influence on blood vessels .