Question

Which of the following is a function of renin?
(a) Stimulation of corpus luteum
(b) Vasodilation
(c) To reduce blood pressure
(d) Conversion of angiotensinogen to angiotensin-I

Answer 1

Renin is a hormone released from the Juxta-Glomerular Apparatus (JGA) and gets activated by a fall in the glomerular blood pressure. It is a part of the renin-angiotensin system.

Complete step by step answer:
The function of renin is to convert angiotensinogen to angiotensin-I. This process occurs when renin is liberated from blood and acts on angiotensinogen. The angiotensinogen layer then goes through proteolytic cleavage to make decapeptide angiotensin I.

So, the correct answer is the option (d), ‘Conversion of angiotensinogen to angiotensin- I.’

Additional Information: Let us know some more about renin-angiotensinogen system:
- This system consists of renin, angiotensin I, angiotensin II and angiotensin- converting enzyme (ACE) .
- Renin, after being liberated from blood acts on the circulating layer called angiotensinogen and converts it to angiotensin-I through proteolytic cleavage.
- The enzyme called angiotensin separates two amino acids and forms angiotensin II and other tissues in the body. These tissues include the brain and heart as well. Angiotensin enzyme is secreted by vascular endothelium.
- The renin- angiotensin system keeps the balance in blood pressure level in blood cells by releasing renin into the bloodstream.
- The function of this system is:
a) It builds resistance vessels to increase arterial pressure and vascular resistance.
b) This system stimulates the delivery of sodium at different renal tubular sites.
c) Provides the release of norepinephrine from the sympathetic nerve and also prevents norepinephrine uptake.
d) Stimulates vascular hypertrophy and cardiac hypertrophy.

Note: When blood pressure falls in the glomerulus, the JGA or Juxta- Glomerular Apparatus releases renin that converts angiotensinogen in the blood to angiotensin- I. And later it converts into angiotensin II. The angiotensin II increases the glomerular blood pressure and further glomerular filtration rate (GFR). It also activates the adrenal cortex to release aldosterone. The aldosterone further causes reabsorption of water from the distal part of the tubule and leads to an increase in blood pressure and GFR. This system is known as the Renin- Angiotensin- Aldosterone system.