Page 111 - Physiology and Pathophysiology MNU 2024-2025 نظرى

Clinical pharmacy 2024/2025 Level 2 Pharm D Physiology and Pathophysiology (MD303)

Ascending Limb LH Descending Limb LH
1) NaCI ➔ actively extruded from the ascending limb into surrounding interstitial ✓ Deeper regions of medulla reach 1400 mOsm/L.

fluid. ✓ Impermeable to passive diffusion of NaCI

+
+
-
 Na diffuses into tubular cells with the secondary active transport of K and Cl . ✓ Permeable to H20
+
-
+
 Occurs at a ratio of 1 Na and 1 K to 2 Cl . ✓ Hypertonic interstitial fluid causes H20 movement
+
+
+
2) Na is actively transported across the basolateral membrane by Na / K ATPase out of the descending limb via osmosis, and H20
pump. enters capillaries.
-
+
+
3) Cl passively follows Na down electrical gradient. ✓ Fluid volume  in tubule, causing  [Na ] in the
+
4) K passively diffuses back into filtrate. ascending limb.
 Ascending walls are impermeable to H2O.

| P a g e 79