PEX-09-03. Autoregulation allows the glomerular filtration rate (GFR) to remain

Question

PEX-09-03. Autoregulation allows the glomerular filtration rate (GFR) to remain relatively constant over a wide range of systemic blood pressure. How would your kidneys respond to an extended exercise session (e.g. ultramarathon) where sweating was extensive and was not matched by fluid intake?

Question 4 options:

1)

Blood volume would decrease, so the afferent arteriole would dilate and the efferent arteriole would constrict

2)

Blood volume would increase, so the afferent arteriole would dilate and the efferent arteriole would constrict

3)

Blood volume would increase, so the afferent arteriole would constrict and the efferent arteriole would dilate

4)

Blood volume would decrease, so the afferent arteriole would constrict and the efferent arteriole would dilate

1)

Blood volume would decrease, so the afferent arteriole would dilate and the efferent arteriole would constrict

2)

Blood volume would increase, so the afferent arteriole would dilate and the efferent arteriole would constrict

3)

Blood volume would increase, so the afferent arteriole would constrict and the efferent arteriole would dilate

4)

Blood volume would decrease, so the afferent arteriole would constrict and the efferent arteriole would dilate

Explanation / Answer

Option 4 is the correct answer. Here due to excessive sweating, high fluid loss will occur which results in decrease in mean arterial pressure. Decreased mean arteial pressure is detected by arterial baroreceptors, which results in sympathetic nervous system activation, afferent arteriole constriction, and decreased glomerular filtration rate.

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