Macromolecular Transport

by Thad Wilson, PhD

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    Now, let’s go ion by ion through these processes of transport. Glucose Remember I said, almost all of glucose is reabsorbed in the first 25 percent of the proximal tubule. How does this happe? Well, we have 2 transporters involved. The SGLT2 is a transporter that will move both sodium and glucose across the apical membrane. Why does sodium travel with glucose at this particular transporter? It’s all because of that sodium-potassium ATPase on the basolateral side. That pump sets up the driving force. And so sodium is actually used, in this case, as energy to move across the glucose molecule across the apical membrane. Then glucose leaves the basolateral membrane by a different transporter known as a GLUT2. The majority of the particular transporters, or amounts of glucose, will be reabsorbed by this SGLT2. There’s a very small amount though that escapes past the SGLT2, and that’s usually picked up by the SGLT1. This transporter is less quick in transporting things across the apical membrane, but it has a very high affinity. So it’s a good clean-up molecule to transport the last few things across. So this SGLT1 is the clean-up one, and the SGLT2 is the big work horse to get most of the glucose across the apical membrane. Later on in this SGLT1 scenario, you use a different GLUT molecule to get the glucose across the basolateral membrane. It’s known as a GLUT1. So SGLT2 is linked with GLUT2 and SGLT1 is linked to GLUT1. Now, peptides, again, are reabsorbed very quickly across the proximal tubule and are pretty much all reabsorbed by the time you end the proximal tubule. How does this occur? Well, you have things like di- and tripeptides, even amino acids that are being traveled down the renal tubule because these are all...

    About the Lecture

    The lecture Macromolecular Transport by Thad Wilson, PhD is from the course Renal Physiology.

    Included Quiz Questions

    1. SGLT1
    2. SGLT2
    3. GLUT1
    4. GLUT2
    1. Phosphate
    2. Bicarbonate
    3. Chloride
    4. Sodium
    1. SGLT2
    2. GAT
    3. GLUT4
    4. SLC34
    5. GLUT5
    1. Peptides
    2. Small proteins
    3. Phosphate
    4. Glucose
    1. it increases calcium concentration in plasma
    2. It increases phosphate absorption
    3. It decreases bone reabsorption
    4. It increases bone absorption
    5. It decreases calcium reabsorption

    Author of lecture Macromolecular Transport

     Thad Wilson, PhD

    Thad Wilson, PhD

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