Kidney 2 Flashcards
(34 cards)
Explain what the cells look like at the PCt, dct and collecting duct
Single epithelial cells which have interdigitations and microvilli
Also many organelles eg for protein synthesis and mitochondria
How are loop of henle cells different
They are flatter and less organelles needed
What are the 2 membrane sides in reabsorption
Apical (closer to lumen) and baso lateral into the ecf and peritubular capillaries
Name a few types of transport for reabsorption
Transcrllular (Co transport, carrier, antiporter, symporter)
What does paracellular movement mean
Via gap junctions eg water movement
Why are interdigitations needed at the baso lateral membrane
Shorter distance for atp movement from mitochondria for active transport
Which ion usually moves with na in reabsorption and how
Cl- via paracellular movement down electrochemical gradient
What is the only way glucose is fully reabsorbed at PCt
Na cotransporter and then carrier at baso lateral membrane
Which 3 ways can urate be reabsorbed at pct
Anion transporter , paracellular or transcellular
How do peptides / AA get fully reabsorbed at pct
Endocytosis in via the apical membrane then degraded by lysosomes then reabsorbed via transporters through basolateral
What is Tm on the graph of glucose reabsorption at PCT
Transport max rate
The saturation point of carriers no more reabsorption
Why is Tm so low with diabetics
High glucose means too much saturation
Which kind of things can be secreted into the pct from peritubular capillaries and how
Urate, drugs
Can be via anion/cation transporters
Eg anion transporter for urate
What is the fluid called leaving the pct and what osmotic state does it need to have
Tubular fluid
Always isosmotic to the plasma (less ions etc more water)- lower osmolarity
Cortex is always isosmotic eg pct , what is medulla
More concentration ie hyperosmotic as more water reabsorbed
Why does osmolarity get higher down the descending limb into the medulla
Because it’s permeable to water so water is reabsorbed in to capillaries again = higher osm
Why does osmolarity start to decrease up the ascending limb
Ions are actively transported out for reabsorption at the ascending limb
How is concentrated urine produce
Increased reabsorption at collecting duct and descending limb of h20
Which 2 things allow for water reabsorption to allow concentrated urine
ADH
Countercurrent systems
what do counter current systems allow
Osmotic gradient to allow for reabsorption
Give the main example of counter current exchange and how it works
Collecting duct osmolarity low compared to high ascending vasa recta
This allows water to move from low osm at collecting duct to the ascending vasa recta
What would happen if water wasn’t removed from medulla into vasa recta
No osmotic gradient so water isn’t reabsorbed
How is counter current multiplier different to exchanger ct to vasa recta
CCM is exchange actively between the loop of henle and the vasa recta
If the medullary interstitum was kept at a low OSM what would happen
Water wouldn’t be reabsorbed but excreted
