Glomerular filtration, tubularReabsorption and tubular Secretion

Glomerular Filtration
1. 180L/day
  1. 125ml/min
2. GFR = Kf x Net filtration pressure (NFP)
  1. (NFP) = (PGC – PBS) – (OnGC - OnBS)
  2. Kf (filtration coefficient) depends on • the hydraulic conductivity (permeability) of the capillary and • the effective surface area available for filtration.
3. GFR is directly related to blood pressure
4. sympathetic stim DECREASE GFR
5. not a selective process
Tubular Reabsorption
1. All except potassium
2. Na+-K- pump and carrier proteins (e.g. glucose transporter or GLUT) always reside on the basolateral membrane.
3. 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.
4. diffusion
  1. Na+, K+, Cl-, urea in the PCT
Morphology of epithelial cells lining various sections of the nephron
Reabsorption in the Loop of Henle
1. descending
  1. water ONLY
2. ascending
  1. Electrolytes
Reabsorption in the early Distal Convoluted Tubule (DCT)
1. Ca2+
  1. passive transport
Reabsorption and Secretion in the Collecting Duct
1. Principal cells reabsorb Na+ and secrete K+
  1. target for aldosterone and ADH
2. intercalated cells reabsorb K+ and HCO3-, and secrete H+
tubular secretion
1. PCT
  1. H+: variable (via Na+-H+ antiporters)
  2. NH4+: variable, increase in acidosis (antiporters)
  3. Urea: variable (diffusion)
  4. Creatinine: small amount
2. thin LoH
  1. Urea: variable (recycling from collecting duct)
  2. NH4+: variable (recycling from thick ascending loop of Henle)
3. CD
  1. K+: variable amount to adjust to dietary intake (via leakage channels of the principle cells)
  2. H+: variable amount to maintain acid-base homeostasis (via proton pump)
Sites of action of diuretics
Summary of basic renal processes

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Glomerular filtration, tubularReabsorption and tubular Secretion

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	Criado por Zulhilmi Zainal quase 11 anos atrás