Chapter 19, Problem 1E

Summary Introduction

Introduction:

Renin is an enzyme that is secreted by juxtaglomerular kidney cells and stored in the kidneys. It promotes the protein angiotensin production. It ultimately causes an increase in blood pressure and leads to the rebuilding of perfusion pressure in the kidneys.

Answer to Problem 1E

Solution:

The correct answer is the option (c) a decrease in the activity of renal sympathetic nerves.

Explanation of Solution

Explanation/justification for the correct answer:

The correct option (c) a decrease in the activity of renal sympathetic nerves. The decrease in the sympathetic stimulation activity leads to the vasodilation and raised blood flow across the kidneys during the resting conditions. When the action potentials frequency increases, then the vasoconstriction occurs that results in low glomerular flow. Thus, less filtration occurs. This results in the drop of renin secretion. Hence, the option (c) is correct.

Explanation for incorrect answer:

Option (a) a decrease in the mean arterial pressure. A drop in the arterial blood pressure leads to a decrease in blood volume. It is the direct link between the renin secretion and blood pressure. Hence, the option (a) is incorrect.

Option (b) a decrease in the pressure inside the afferent arteriole. Thus, a decrease in blood pressure leads to the in afferent arterioles dilation. It increases the GFR due to larger blood flow to the glomerulus. Hence, the option (b) is incorrect.

Option (d) a decrease in the concentration of sodium chloride in tubular fluid. It is a drop-in blood pressure that leads to a low sodium chloride concentration at the distal tubule. Hence, the option (d) is incorrect.

Option (e) a decrease in GFR. Increased hydrostatic pressure in Bowman's capsule will show a decrease in Glomerular Filtration Rate or GFR. Hence, the option (e) is incorrect.

Conclusion

When there is a decrease in the renal sympathetic nerves activity it results in the decrease of the renin secretion. Hence, the option (c) is correct.