Kaplan FL2 BB #8 *SPOILER*

[specterMD]

So I just finished taking Kaplan's Full Length #2 (504 -- 126/126/126/126) and am super confused on this question.

Wouldn't an increase in blood volume cause an increase in blood pressure? My confusion is because ADH (anti-diuretic hormone) causes an increase in blood pressure by retaining fluid thus increasing blood pressure -- while the opposite of this would be the release of ANP (atrial naturietic peptide) causing a decrease in blood pressure by excreting fluids.

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[Cornfed101]

nitric oxide doesn’t increase overall blood volume. It is primarily a vasodilator and with increased blood vessel diameter and the same volume you get decreased pressure.

 

[Blueprint Med School]

I think all of your thinking is correct, but I think your confusion lies in thinking that NO increases blood volume? ANP and NO decrease blood pressure in opposite ways. NO increases blood vessel diameter while keeping blood volume constant, while ANP decreases blood volume while keeping blood vessel diameter constant.

Think of it like having a hose. If you wanted to decrease the water pressure, you could either run less water through the hose, or you could make the hose extremely wide.

Kevin W, MCAT Tutor
Med School Tutors