General

Question 1

What triggers the release of renin, and where is it secreted from?

Answer 1

From JGA in response to:

Decreased BP in afferent arteriole

Decrease in BP in carotis sinus, via sympathetic fibres acting on JGA

Decrease in Na in DCT - cells in JGA detect and release renin.

Question 2

What is the function of renin?

Answer 2

converts angiotensinogen (from the liver) into angiotensin 1

Question 3

What is the fate of angiotensin 1?

Answer 3

Converted into angiotensin 2 by ACE in the lung capillery epithelium.

Question 4

What are the actions of angiotensin 2?

Answer 4

• Vasoconstriction
• Causes the release of aldosterone from the zona glomerulosa (adrenal cortex)
• Hypothalamus - PPG secretion of ADH
• Activates thirst centre

Question 5

What are the actions of aldosterone?

Answer 5

• Encourage reabsorption of Na - WATER FOLLOWS
• Encourage excretion of K

Question 6

What are the actions of ADH?

Answer 6

Acts on DCT to increase the number of aquaporins. Water mose down the osmotic gradient out of the DCT into the renal medulla.