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Title: Kidneys filter a large volume of fluid, putting it on a path to ultimate disposa Post by: SRUB on Nov 30, 2014 Kidneys filter a large volume of fluid, putting it on a path to ultimate disposal, and then reabsorb nearly all of it back into the body. Only a few waste products are actively secreted into the tubule. Why are the kidneys set up in this way? Wouldn’t it be easier and more energetically efficient to selectively secrete only the waste molecules and the exact right amount of excess water and ions?
Title: Re: Kidneys filter a large volume of fluid, putting it on a path to ultimate disposa Post by: bio_man on Dec 1, 2014 Kidneys filter a large volume of fluid, putting it on a path to ultimate disposal, and then reabsorb nearly all of it back into the body. Only a few waste products are actively secreted into the tubule. Why are the kidneys set up in this way? Wouldn’t it be easier and more energetically efficient to selectively secrete only the waste molecules and the exact right amount of excess water and ions? The Bowman's capsule is a selectively permeable membrane, it is the first part of nephron where filtrate is collected. I'm not sure how to approach this, then to say that this already happens to an extent. Water, ions, and other smaller molecules are difficult to detect due to their size. For this reason, we've evolved the ability to regain those lost ions. What are your thoughts on the matter? |