Chapter 2 part 1

Back by popular demand…all two of you…the second chapter of The Clinical Physiology of Acid Base and Electrolyte Disorders.

Chapter Outline

- Renal Circulation and GFR

    - RBF is 20% of cardiac output

        - In terms of mL per 100 g organ weight it is 4x the liver and exercising muscle and 8x coronary blood flow!

        - After the glomeruli the efferent arteriole have two fates

            - Peritubular capillaries in the cortex

                - Peritubular capillaries are not necessarily associated with their parent glomeruli. Weird.

            - Vasa recta from juxtamedullary glomeruli in the medulla

Joel Says: This seems wrong. Solute balance can be maintained down to a very low GFR. The R^2 here would be very low. Prove me wrong.

    - States that GFR is an important determinant of solute and water excretion.

- Glomerular anatomy and function

    - Structure

        - Glomerulus is a tuft of capillaries

            - Enclosed in a capsule of epithelial cells, called Bowman’s capsule

            - The epithelial cells of Bowman’s capsule are continuous with the epithelial cells of the proximal tubule

Josh says: Look at the review in Nature Reviews Nephrology from Rachel Lennon’s group

Complexities of the glomerular basement membrane

        - Filtration barrier

            - Epithelial cell (podocyte)

                - Epithelial cells adhere to the basement membrane via foot processes and the foot processes have slit diaphragms 

            - Basement membrane

Melanie talks about conduits through the glomeruli. Here is a cool review:

Why until just now? Undiscovered uniqueness of the human glomerulus! by L. Gabriel Navar, Owen Richfield

Am J Physiol Renal Physiol. 2018 Nov 1; 315(5): F1345–F1346. Published online 2018 Aug 15. doi: 10.1152/ajprenal.00369.2018 PMCID: PMC6293291

                - Produced by both the endothelial cells and podocytes

                - Formed from type IV collagen

                    - Abnormalities of type 4 collagen cause Alport

                        - The gene coding for the alpha 5 chain is the culprit

                        - COL4A5

                    - Abnormal Alpha 3 and 4 chains can also cause hereditary nephritis