Question

Describe the mechanisms of blood pressure regulation for renin angiotensin system.

Answer 1

Blood pressure is the force exerted by the blood against wall of artery when it flow through it. Normal blood pressure usually mentioned as 120/80mmHg. 120mmHg is systolic pressure (Pressure created when heart contract) and 80mmHg is diastolic pressure (Pressure created when hear relax). When blood pressure is altered, there are several mechanisms that bring the blood pressure to the normal. Renin angiotensin system is one among them

Regulation of Blood Pressure by Renin Angiotensin System

When blood pressure decrease renal blood supply also decreases. Decreased blood flow through kidney stimulate juxtaglomerular apparatus in kidney resulting release of a hormone called renin. Renin catalyses convertin of angiotensinogen (released from the liver) to angiotensin I. An enzyme from the lung called as Angiotensin Converting Enzyme (ACE) catalyses the convertion of angiotensin I to angiotensin II. This angiotensin II have two main functions in regulation of blood pressure

1. Angiotensin II causes vasoconstriction of blood vessels result in increased peripheral vascular resistance that will ultimately increases blood pressure (because blood pressure directly proportional to peripheral vascular resistance)
2. Angiotensin II stimulates the adrenal cortex and releases aldosterone from the adrenal cortex. Aldosterone enhances sodium and water absorption from the kidney tubules result in increased blood volume that increases cardiac output, ultimately increases blood pressure (Since Cardiac output is directly proportional to blood pressure)