Tubular reabsorption part 1

Kidney tubule 1

 

Kidney tubule 2

 

Total plasma volume filters into the renal tubules about every 22 minutes, so all plasma  would be drained  away as urine in less than 30 minutes were it not for the fact that most of the tubule contents are quickly reclaimed  and returned to the blood. This reclamation process, called tubular reabsorption, is a selective transepithelial process that begins as soon as the filtrate enters the proximal tubules. To reach the blood, reabsorbed substances follow either  either the transcellular or paracellular route. In the transcelullar route, transported transported substances move through the luminal membrane, the cytosol, and the basolateral membrane of the tubule cell and then the endothelium of the peritubular capillaries.  Movement of substances in the paracellular route between the tubule cells is limited because these cells are connected by tight junctions. In the proximal nephrons, however, these tight junctions are “leaky” and allow some important ions (Ca2+, Mg2+, K+, and some Na+) through the paracellular route.

Given healthy  kidneys, virtually all organic nutrients  such as glucose and amino acids are completely reabsorbed to maintain or restore  normal plasma concentrations. On the other hand, the reabsorbtion of water and many ions  is continuosly regulated and adjusted in response to hormonal signals. Depending of the substances transported, the reabsortion process  may be passive (no ATP required) or active (at least one of its steps is driven by ATP directly or indirectly)

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12 Responses to Tubular reabsorption part 1

  1. I really enjoy your blog!

    Liked by 2 people

  2. Xeno says:

    How we work at a cellular level is amazing and we still know so little. If we knew enough, we could take a pill and grow a new kidney. 🤖 Thanks for this post.

    Liked by 3 people

  3. Harbans says:

    Informative indeed.

    Liked by 1 person

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  5. Reblogged this on By the Mighty Mumford and commented:
    RENAL FUNCTION—SOMETHING I’M GROWING MORE FAMILIAR WITH! UP CLOSE AND PERSONAL!

    Liked by 1 person

  6. Freaky…advanced Biology.

    Liked by 3 people

  7. colonialist says:

    The content is fascinating, but it would be helpful if terms like ATP were clarified, even if they are completely familiar to biologists.

    Liked by 1 person

  8. This was so clearly explained.
    Could you write one on impulse transmission? And if u already have, can u please give me the link…

    Liked by 1 person

  9. Ferret Chef says:

    takes me back to my uni days – loved physiology.

    Liked by 2 people

  10. Kelly MacKay says:

    Very interesting

    Like

  11. Equipping says:

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    Liked by 1 person

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