Question

There can be more than one right answer.

13. Which of the following changes will lead to a decrease in Na+ reabsorption?

A. decreased stroke volume

B. dilation of afferent arterioles

C. decreased paracrine agent delivered to JG cells by macula densa

D. less angiotensinogen secreted by the liver

E. less ANP secreted by the atria

Answer 1

B. dilation of afferent arterioles

C. decreased paracrine agent delivered to JG cells by macula densa

D. less angiotensinogen secreted by the liver

Explanation: Any decrease in filtrate formation or decrease GFR results in decrease NaCl delivery to the macula densa. This leads to stimulation of the JG cells to secrete Renin that converts angiotensinogen to Angiotensin I which in turn is converted to angiotensin II, this in turn stimulate the release of aldosterone that increases sodium reabsorption.

So less angiotensinogen would lead to less Na+ reabsorption.

Dilatation of the afferent arteriole increases GFR that in turn increases the delivery of NaCl to macula densa resulting in inhibition of Renin-Angiotensin-Aldosterone system resulting in a decrease in Na+ reabsorption.