aldosterone effect on osmolarity

[balopathic45]

my EK book says "each NaCl is reabsorbed with a corresponding water molecule so while the total amount of salt in the body increases, the concentration of salt in the bloodstream remains the same... the main effect is to increase plasma volume without affecting plasma osmolarity"

My problem with this is that if only one molecule of water is being absorbed for one NaCl (that has a Van't Hoff factor of 2) shouldn't this result in an increase in osmolarity according to the equation Π=iMRT because you'll have Na+ and Cl- in the aqueous environment?

---

Members don't see this ad.

 

[MCATforsale1]

hmmm

 

[sazerac]

The fact that you can even ask this question means you understand the topic beyond what the MCAT will expect from you. My professional advice is to keep it simple, and move on.

 

[balopathic45]

The fact that you can even ask this question means you understand the topic beyond what the MCAT will expect from you. My professional advice is to keep it simple, and move on.

yeah you're right; i did the quick math anyways because even 1 molecule of water per 1 Na+ sounded fishy (in actuality 55 molecules of water are needed to maintain osmolarity) and it looks like they said that for simplicity's sake.

thanks!