Lecture 31 – Renal Physiology VI

Loop of henle does nothing in regard to acid base

Info icon This preview shows pages 3–5. Sign up to view the full content.

Loop of Henle does nothing in regard to acid-base balance Only generates and maintains the medullary osmotic gradient Some are reabsorbed in thick portion, bot not for acid base Intercolated cells of the DT and CS ad the secretion of H is coupled to the synthesis of  new bicarbonate There isn’t much bicarbonate left at this point because its been reabsorbed, so it has to  be synthesized All bicarbonate that appears has to be synthesized Intercolated cells have different proteins than the epithelial cells lining the PT Basolateral membrane
Image of page 3

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

Bicarbonate cl antiporters that move bicarbonate out of the cell and into the peritubular  fluid Chloride channels that allow Cl to diffuse back into the peritubular cell (out of the cell) Apical membrane H pumps that use ATP to transport H into the tubular fluid K/H antiporters that transport K into the cell and H out of the cell CA only exists as a cytosolic enzyme of the intercolated cells [CO2] can increase either from cellular metabolism or transport in by diffusion from the  peritubular fluid this is all by the glomerulus, but by the distal tubule, so near JGA there is CO2 in this fluid so it can diffuse in in the cytosol, CO2 combines with water via CA which forms carbonic acid which then  dissociates into H and bicarbonate this reaction is driven to the right by the removal of H and bicarbonate from the cell the end products are removed, so this reaction is continually driven- never reaches EQ the H is transported across the apical membrane by either the H pumps or the K/H  antiporters the bicarbonate is transported into the peritubular fluid by he bicarbonate/chloride  antiporters it then diffuses into the plasma ***this bicarbonate ion is NOT being reabsorbed, because it was never in the  tubular fluid it is newly synthesized from CO2 and water in the epithelial cell so it never came from  the peritubular fluid it is put back in the plasma where it can respond to changes in pH as a buffer as you excrete protons into the tubular fluid, the pH will drop within the tubular fluid/urine this drop is limited because the pH in the tubular fluid can’t get lower than 4.5
Image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.
  • Spring '13
  • ArthurDunham
  • Physiology, epithelial cell, peritubular fluid

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern