III: Tubular Transport II Flashcards
Histology of thin descending and ascending limb membrane
Epithelial membrane without brush border + LOW metabolic activity
Histology of thick ascending limb membrane
Thick epithelial membrane + HIGH metabolic activity
In pictures, differentiate between thin and thick limb of loop of henle
Thin descending loop of henle looks round with 2/3 round cells
Thick ascending loop of henle looks round with MANY round cells
Thin descending limb contains in both membranes
AQP1
In thin descending limb what is reabsorbed
High H2O and low solute reabsorption
There is an increase osmolarity in
Tubular lumen
How much H2O is reabsorbed in the loop of henle
20%
Thin ascending limb is permeable/nonpermeable to water
Impermeable
Where does reabsorption of Cl- begin
At thin ascending limb
Reabsorption of Cl- in ascending limb through
Transcellular pathway (CLC-K1)
Na+ reabsorption is through
Paracellular pathway
In thick ascending limb, what is reabsorbed
Solutes and not water
How much filtered Na+ and Cl- does the THICK ascending limb reabsorb
25%
K+, Cl- and Ca++ also reabsorbed in the
Thick ascending limb
Descending and ascending limb permeability
Descending is permeable
Ascending is impermeable
Descending reabsorbs water
Ascending reabsorbs solutes
What is reabsorbed in thick ascending limb
Na+, K+, Cl-, HCO3-, Mg+
Channels involved in Thick ascending limb (reabsorption of Na+, Cl-, K+, Mg++, Ca++, HCO3-)
NHE3 (H+, Na+) AQP NKCC2 (Na+, 2Cl-, K+) ROMK (K+) Na+/K+ATPase
Direct ones for K+ and Cl-
Why is there a decrease in tubular osmolarity in thick ascending limb
Because no H2O is reabsorbed
Distal convoluted tubule sections
Initial portion Distal portion (connecting tubule)
Collecting tubule sections
Cortical
Medullary
Initial part of distal convoluted tubule called the
Cortical diluting segment