Post on 06-Nov-2015
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NEFROFISIOLOGIFiltrasi-Reabsorbsi-Sekresi-EkskresiBy Sawiji AmaniMobile phone: 081 328 028333E-mail: sawijiamani@gmail.com
Lecturer and ResearcherNursing Basic Science DepartmentMuhammadiyah Gombong University 2010
Figure 7a: Urinary system
Figure 7b: Structure of a kidney
Figure 7c: Nephron
Figure 7d: Filtration, reabsorption, secretion, and excretion
Glomerular Flow Rate (GFR)CapillaryHydrostatic pressureColloidal Capsule pressureBack pressureNet Filtration pGFR 180L/day (about 1% is excreted)Figure 19-6: Filtration pressure in the renal corpuscle
Figure 7h: The filtration fraction
Figure 7e: Sodium reabsorption in the proximal tubule
Figure 7f: Sodium-linked glucose reabsorption in the proximal tubule
Figure 7g : Passive reabsorption of urea in the proximal tubule
Peritubular capillary pressure favor reabsorption (Silverthorn, 2007: 629-630)The reabsorption we have just discussed refers to the movement of solutes and water from the tubule lumen to the interstitial fluid.How does that reabsorbed fluid then get into the capillary?The answer is that the driving force for reabsorption from the interstitial fluid into the capillaries is the low hydrostatic pressure that exist along the entire length of peritubular capillaries. This low pressure favors reabsorption.
The peritubular capillaries have average hydrostatic pressure of 10 mmHg (in contrast to the glomerular capillaries, where hydrostatic pressure averages 55 mmHg).Colloid osmotic pressure, which favors movement of fluid into the capillaries, is 30 mmHg.As a result, the pressure gradient in peritubular capillaries is 20 mmHg, favoring the absorption of fluid into the capillaries.Fluid that is reabsorbed passes from the capillaries to the venous circulation and returns to the heart.
SECRETION
Figure 7i: The micturition reflex