Kidney 2 Flashcards
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
Why does the ascending limb become high in OSM in counter current multiplier
Because na / Cl/ k are actively transported to the vasa recta from the ascending limb
Why does ascending vasa recta have lower osm (more water) than the descending
Descending is getting all the ions in exchange but also it transfers water to the ascending limb which also increases osm
Which type of transport doesn’t happen in active reabsorption at ascending limb
Paracellular transport
Regulation of ph is also important , what is it called the mechanism which balances H and HCO- in the blood and ecf
Renal adjustment
Which 2 types of cells manage change in ph in the collecting duct
A cells - manage acidosis (too much H)
B cells - manage alkalosis (too much HCO-)
Which enzyme is present in a and B cells for maintaining ph
Carbonic anhydrase
What happens to HCO and H levels in acidosis with a cells
Carbonic anhydrase is used to allow active excretion of H into the lumen of collecting duct actively or passively
HCO is also reabsorbed to the ecf to combat acidosis
Which ion is reabsorbed along with HCO in acidosis repair by a cells and why
K+
Because the K+/ H antiporter moves K into a cell which needs to be then reabsorbed into blood
What happens with B cells to repair alkalosis
HCO passively moved to the lumen to be excreted and H+ is actively transported via H/K antiporter back to ecf
What happens to the K in alkalosis B cells
K is then excreted when it’s moved into cell via antiporter
