Question

WRITE AN ESSAY ON THE RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM

Answer 1

Renin-angiotensin-aldosterone system is a hormone system which maintain blood pressure, fluid regulation and electrolyte balance in the body.

Renin-angiotensin-aldosterone system activates when blood pressure falls down. A decrease in blood pressure is sensed by the kidney cells resulting into release of renin. Renin converts angiotensinogen into angiotensin I which is converted into angiotensin II by angiotensin converting enzyme (ACE). Angiotensin II brings many changes in order to maintain blood pressure, fluid volume and electrolyte balance:

1. Angiotensin II stimulates sympathetic nervous system resulting into increased heart rate and thus increases blood pressure.

2. Enhances tubular Na+, Cl- reabsorption, and K+ excretion by the kidney.

3. Stimulates adrenal gland cortex to release aldosterone which causes water retention.

4. Causes arteriolar vasoconstriction resulting into increased blood pressure.

5. Stimulates posterior lobe of pituitary gland to release anti-diuretic hormone (ADH) which acts on collecting duct and enhances water reabsorption.