Tubular Transport - McCormick Flashcards
Pinocytosis
Protein reabsorption
Proximal tubule reabsorbs what?
Na+ K+ Cl- HCO3- Ca2+ Phosphate water ALL glucose, AA
TF/P ratio in Proximal tubular lumen of inulin
Starts at 1
Goes to 3 - water has left, inulin concentration stays same in less water
TF/P ratio in Proximal tubular lumen of glucose
Starts at 1
Goes to 0 - all of the glucose has been reabsorbed
TF/P ratio in Proximal tubular lumen of PAH
Starts at 1
Goes to 10 - PAH is secreted
Transporters in the proximal tubule
Na - Glucose
Na+ - H+
Transporter in the PT interstitium
Na-K ATPase
Transporter on the loop
Na-K-2Cl
As water and Na+ are reabsorbed, what happens to Cl- and urea in PCT?
Become more concentrated in the lumen fluid
-provides driving force for paracellular reabsorption
2 factors promoting fluid movement into peritubular capillaries?
High plasma colloid osmotic pressure
Low hydrostatic pressure in these capillaries
What regulates plasma concentrations of glucose and AA?
Liver and endocrine system
-secondary active transport, transcellular only
Mechanism of glucose reabsorption
Coupled reabsorption of Na+ and glucose in PT
Na-glucose cotransport
Facilitated diffusion
Glucosuria
Glucose in urine
Capacity of transporters saturated
-same idea applies to AA
Tmg
Tubular glucose maximum
-rate of glucose reabsorption by all nephrons combined
2 consequences of osmotic diuretics
Increased water excretion
Increased sodium excretion
