practice exam bio question

[astronaut135]

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If Steve’s blood pressure had increased significantly more than Joe’s increased (other factors being equal) while they worked, what difference in their urinary system function would be expected?

A) Joe’s glomerular filtration rate would increase more than Steve’s would.
B) Steve’s reabsorption rate of glomerular filtrate by the peritubular capillaries would be lower than Joe’s would be.
C) Steve’s reabsorption rate per milliliter of glomerular filtrate by the peritubular capillaries would be higher than Joe’s would be.
D) Steve’s glomerular filtration rate would increase more than Joe’s would.

The answer is D, and now looking at it this makes total sense, since increased blood pressure would increase the glomerular filtration rate. But when I first read the question, I took Steve's BP increase as an indication of sympathetic response, which decreases urination. So I put down C. How come that can't be an answer as well?

Thanks in advance!

 

[monkeyvokes]

If Steve’s blood pressure had increased significantly more than Joe’s increased (other factors being equal) while they worked, what difference in their urinary system function would be expected?

A) Joe’s glomerular filtration rate would increase more than Steve’s would.
B) Steve’s reabsorption rate of glomerular filtrate by the peritubular capillaries would be lower than Joe’s would be.
C) Steve’s reabsorption rate per milliliter of glomerular filtrate by the peritubular capillaries would be higher than Joe’s would be.
D) Steve’s glomerular filtration rate would increase more than Joe’s would.

The answer is D, and now looking at it this makes total sense, since increased blood pressure would increase the glomerular filtration rate. But when I first read the question, I took Steve's BP increase as an indication of sympathetic response, which decreases urination. So I put down C. How come that can't be an answer as well?

Thanks in advance!

maybe it's the (other factors being equal) sentence?

 

[onedirection]

The sympathetic system decreases urine?

 

[monkeyvokes]

The sympathetic system decreases urine?

found this to clarify:

"Urinary System:

Kidneys:
(S) – decreases urine production
(P) – increases urine production
Urinary bladder:
(S) – constricts sphincter and relaxes urinary bladder
(P) – tenses urinary bladder and relaxes sphincter to eliminate urine

"

 

[astronaut135]

ah you're probably right. gotta read more carefully. thanks!

 

[Proof]

C cant be the answer because the reabsorption rate PER milliliter of filtrate should remain the same. Steve has a higher GFR than Joe so the peritubular capillaries would most likely reabsorb more but at the same rate. In order to change the rate, you prob will need to add some additional channels ( sodium channels or aquaporins) into the membrane of the distal tubule.

The sympathetic response will definitely decrease urination because the body needs to focus the blood in regions of higher demand such as your muscles. Thus, blood would be directed away from the kidneys. In this problem, both Steven and Joe are working so both of thier sympathetic systems are on and thus eliminating it as a factor to compare both men's urinary ouput.