Question 🤔🤔 relationship between blood pressure and water reabsorption?
When I google "how does blood pressure affect water reabsorption", results say that "High blood pressure leads to decreased water reabsorption in the kidneys, meaning more water is excreted as urine."
However, I also know that ADH increases blood pressure by increasing water reabsorption. Can someone clarify what is right for me?
3
u/duckduckgo2100 20h ago
I think ADH reduces blood plasma osmolality. ADH collects the water in the collecting duct of the which increases osmolality in the kidneys which means more water will be excreted.
3
u/Fun_Comparison_5149 9/13/24:512 (129/123/131/129) 19h ago
They both are correct each occurs at a different time though. If blood pressure is low, the body will act to increase the blood pressure by increasing blood volume(this is done by retaining water via ADH), less water is excreted by the kidneys. If blood pressure goes to high, the body acts to reduce it by decreasing blood volume(this is done by causing the kidneys to retain less water and excrete more by using the hormone atrial natriuretic peptide (ANP) ).
3
u/need-freetime 19h ago
These are both true. Your body compensates having low bp by releasing ADH to increase water reabsorption (increasing volume).
Adversely, if you have high bp, your body will want to get rid of extra fluid via urine
5
u/Artistic-Energy4519 20h ago edited 19h ago
We usually use ADH and Aldosterone to raise the blood pressure when it is low (think RAAS system, which will generate angiotensin II, which stimulates aldosterone and directly constricts blood vessels. Also, we use ADH when we need to lower blood osmolarity). If blood pressure is already high, it indicates we have enough fluid, and we do not need to reabsorb as much water in the nephron.