Location, Synthesis, Stimulus, Function of Renin?

Question

Please try to answer this how you would a exam question rather than give an internet link.

Answer 1

The enzyme is secreted by the kidney from specialized cells of the nephrons, called juxtaglomerular cells in response to:

1.A decrease in arterial blood pressure (that could be related to a decrease in blood volume) as detected by baroreceptors (pressure sensitive cells). This is the most causal link between blood pressure and renin secretion (the other two methods operate via longer pathways).

2.A decrease in sodium chloride levels in the ultra-filtrate of the nephron. This flow is measured by the macula densa of the juxtaglomerular apparatus.

A).Renin cleaves an inactive peptide called angiotensinogen, converting it into angiotensin I.

B).Angiotensin I is then converted to angiotensin II by angiotensin-converting enzyme (ACE) which is found mainly in lung capillaries.

C). Angiotensin causes blood vessels to constrict resulting in increased blood pressure. Angiotensin also stimulates the secretion of the hormone aldosterone from the adrenal cortex. Aldosterone causes the tubules of the kidneys to retain sodium and water. This increases the volume of fluid in the body, which also increases blood pressure.