Zusammenfassung der Ressource
Glomerular filtration, tubularReabsorption and tubular Secretion
- Glomerular Filtration
- 180L/day
- 125ml/min
- GFR = Kf x Net filtration pressure (NFP)
- (NFP) = (PGC – PBS) – (OnGC - OnBS)
- Kf (filtration coefficient) depends on • the hydraulic conductivity (permeability) of the capillary and • the
effective surface area available for filtration.
- GFR is directly related to blood pressure
- sympathetic stim DECREASE GFR
- not a selective process
- Tubular Reabsorption
- All except potassium
- Na+-K- pump and carrier proteins (e.g. glucose transporter or GLUT) always reside on the basolateral
membrane.
- Na+ channels and co-transporter proteins (e.g. Na+-glucose symporter, Na+- amino acid symporter, Na+-Cl-
symporter, and Na+-H+ antiporter) are on the apical membrane.
- diffusion
- Na+, K+, Cl-, urea in the PCT
- Morphology of epithelial cells lining various sections of the
nephron
- Reabsorption in the Loop of Henle
- descending
- water ONLY
- ascending
- Electrolytes
- Reabsorption in the early Distal Convoluted Tubule
(DCT)
- Ca2+
- passive transport
- Reabsorption and Secretion in the Collecting Duct
- Principal cells reabsorb Na+ and secrete
K+
- target for aldosterone and ADH
- intercalated cells reabsorb K+ and HCO3-, and secrete
H+
- tubular secretion
- PCT
- H+: variable (via Na+-H+ antiporters)
- NH4+: variable, increase in acidosis (antiporters)
- Urea: variable (diffusion)
- Creatinine: small amount
- thin LoH
- Urea: variable (recycling from collecting duct)
- NH4+: variable (recycling from thick ascending loop of Henle)
- CD
- K+: variable amount to adjust to dietary intake (via leakage channels of the principle cells)
- H+: variable amount to maintain acid-base homeostasis (via proton pump)
- Sites of action of diuretics
- Summary of basic renal processes