Question

How does angiotensin increase blood pressure?

Answer 1

Regulating blood pressure by the Renin-Angiotensin-Aldosterone System (RAAS):

1. A chain of chemical events called the renin-angiotensin-aldosterone system is used to control blood pressure.
2. The kidneys release renin when blood pressure drops, usually to below 100 mm Hg.
3. Angiotensinogen (decapeptide) is divided into two pieces by renin, of which Angiotensin I is one.
4. The angiotensin-converting enzyme breaks down angiotensin I into fragments (ACE). Angiotensin II is one such item (octapeptide).
5. The powerful vasoconstrictor angiotensin II works on blood vessels and afferent arterioles to constrict tiny arteries or arterioles, increasing blood flow pressure along with triggering the release of the hormone mineralocorticoids, specifically aldosterone from the adrenal cortex and vasopressin (antidiuretic hormone/ADH) from the pituitary gland (neurohypophysis).
6. Aldosterone and vasopressin synchronously cause the kidneys to retain sodium (salt) and thereby maintains the blood volume regulating the overall blood pressure.