Final Review Deck - Lecture V - Reabsorption and Secretion Flashcards
What membrane of the epithelial cell faces the lumen?
the apical membrane
What membrane of the epithelial cell is on the opposite side of the lumen?
the basolateral membrane
What are the peritubular capillaries doing more of?
reabsorption than secretion and filtration cause low bp
What is the transcellular and paracellular path?
transcellular - goes through the cells
paracellular - goes through the junctions of two cells
What does the sodium potassium pump drive?
the resorption of sodium - it is in the basolateral membrane
What does the transprot of cations drive?
transport of anions through the transcellualr or paracellular pathway
What does the transport of ions drive?
transport of water through transcellualr pathways or paracellular pathway
What does the movement of water increase the concentration of in the lumen and cause them to move as well through the transceullar pathway?
potassium, calcium, urea
Why is all bicrabonate absorbed?
cause it is a base - same with glucose need for energy
How much urea is reabsorbed?
53% - can denature cells in the kidney
In the proximal tubule what is most moving sodium across apical membrane?
sodium proton antiporter
In the proximal tubule how does sodium move across the apical membrane?
Na + Pi symporter - parathyroid hormone increases renal excretion of phopshate by inhibiting this pump to prevent formation of calcium phosphate precipitates
Na + H+ antiporter
Na + Glu symporter
In the proximal tubule how does sodium move across the basolateral membrane?
sodium potassium pump
3 bicarbonate out/ 1 sodium out
glucose always moves acorss
What do protons do on the tubule lumen side?
combine with bicarbonate make carbonic acid and this become water and CO2 which diffuses to the epithelium and the ECF and in the epithelium CO2 combines with water and makes H+ and bicarbonate
What causes the concentration of chloride to be higher in lumen?
due to cations and water leaving creating a gradient for chloride
What happens to proteins that leak out of glomerular capillaries?
bind to receptors in the apical membrane in the proximal tubule and cause endocytosis and they are interalized as vesicles which will go to lysosomes and degrade them or be released back into the ecf via exocytosis
What is the way H+ is secreted i the distal tubule and collecting duct?
not sodium dependent
-H+ ATPase which pumps out protons which come from dissociation of water
-H+/K+ ATPase
-K+ is reabsorbed through K+ channel
What happens to the OH- that comes from dissociation of water?
combines with CO2 and makes bicarbonate which is reabsoirbed by bicarbinate chloride antiporter
-chloride which comes in from this is reabsribed back to ecf through chloride channel in basolateral membrane
Since H+ in urine can make pH 4.5 how is it buffered?
-bicarbonate and makes co2 (reenters epithelial cell to make bicarbonate) and h20
-dibasic phopshate becomes monobasic phophate and sodium is reabsorbed
-ammonia becomes ammonium which cannot diffuse
Where is most of the potassium reabsorbed?
proximal tubule
Where is mot of the potassium secrted thorugh principal cells or reabsrobed by intercalated cells?
distal tubule
Most of the what is happening to potassium in distal tubule?
it is being secrted by principal cells
What is in the apical membrane distal tubule principle cells?
ROMK1 which is open at negative Vm and closes at depolarization and gets potassium in the kidney lumen - 3NA out and 2 K+ in so opem when hyperpolarized
What happens if filtration greater than excretion?
reabsorption
What happen if filtration less than excretion?
secretion
If filtration and secretion are the same?
there is no net
