Kidney 2

Question 1

Explain what the cells look like at the PCt, dct and collecting duct

Answer 1

Single epithelial cells which have interdigitations and microvilli

Also many organelles eg for protein synthesis and mitochondria

Question 2

How are loop of henle cells different

Answer 2

They are flatter and less organelles needed

Question 3

What are the 2 membrane sides in reabsorption

Answer 3

Apical (closer to lumen) and baso lateral into the ecf and peritubular capillaries

Question 4

Name a few types of transport for reabsorption

Answer 4

Transcrllular (Co transport, carrier, antiporter, symporter)

Question 5

What does paracellular movement mean

Answer 5

Via gap junctions eg water movement

Question 6

Why are interdigitations needed at the baso lateral membrane

Answer 6

Shorter distance for atp movement from mitochondria for active transport

Question 7

Which ion usually moves with na in reabsorption and how

Answer 7

Cl- via paracellular movement down electrochemical gradient

Question 8

What is the only way glucose is fully reabsorbed at PCt

Answer 8

Na cotransporter and then carrier at baso lateral membrane

Question 9

Which 3 ways can urate be reabsorbed at pct

Answer 9

Anion transporter , paracellular or transcellular

Question 10

How do peptides / AA get fully reabsorbed at pct

Answer 10

Endocytosis in via the apical membrane then degraded by lysosomes then reabsorbed via transporters through basolateral

Question 11

What is Tm on the graph of glucose reabsorption at PCT

Answer 11

Transport max rate

The saturation point of carriers no more reabsorption

Question 12

Why is Tm so low with diabetics

Answer 12

High glucose means too much saturation

Question 13

Which kind of things can be secreted into the pct from peritubular capillaries and how

Answer 13

Urate, drugs

Can be via anion/cation transporters

Eg anion transporter for urate

Question 14

What is the fluid called leaving the pct and what osmotic state does it need to have

Answer 14

Tubular fluid

Always isosmotic to the plasma (less ions etc more water)- lower osmolarity

Question 15

Cortex is always isosmotic eg pct , what is medulla

Answer 15

More concentration ie hyperosmotic as more water reabsorbed

Question 16

Why does osmolarity get higher down the descending limb into the medulla

Answer 16

Because it’s permeable to water so water is reabsorbed in to capillaries again = higher osm

Question 17

Why does osmolarity start to decrease up the ascending limb

Answer 17

Ions are actively transported out for reabsorption at the ascending limb

Question 18

How is concentrated urine produce

Answer 18

Increased reabsorption at collecting duct and descending limb of h20

Question 19

Which 2 things allow for water reabsorption to allow concentrated urine

Answer 19

ADH

Countercurrent systems

Question 20

what do counter current systems allow

Answer 20

Osmotic gradient to allow for reabsorption

Question 21

Give the main example of counter current exchange and how it works

Answer 21

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

Question 22

What would happen if water wasn’t removed from medulla into vasa recta

Answer 22

No osmotic gradient so water isn’t reabsorbed

Question 23

How is counter current multiplier different to exchanger ct to vasa recta

Answer 23

CCM is exchange actively between the loop of henle and the vasa recta

Question 24

If the medullary interstitum was kept at a low OSM what would happen

Answer 24

Water wouldn’t be reabsorbed but excreted

Question 25

Why does the ascending limb become high in OSM in counter current multiplier

Answer 25

Because na / Cl/ k are actively transported to the vasa recta from the ascending limb

Question 26

Why does ascending vasa recta have lower osm (more water) than the descending

Answer 26

Descending is getting all the ions in exchange but also it transfers water to the ascending limb which also increases osm

Question 27

Which type of transport doesn’t happen in active reabsorption at ascending limb

Answer 27

Paracellular transport

Question 28

Regulation of ph is also important , what is it called the mechanism which balances H and HCO- in the blood and ecf

Answer 28

Renal adjustment

Question 29

Which 2 types of cells manage change in ph in the collecting duct

Answer 29

A cells - manage acidosis (too much H)

B cells - manage alkalosis (too much HCO-)

Question 30

Which enzyme is present in a and B cells for maintaining ph

Answer 30

Carbonic anhydrase

Question 31

What happens to HCO and H levels in acidosis with a cells

Answer 31

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

Question 32

Which ion is reabsorbed along with HCO in acidosis repair by a cells and why

Answer 32

K+

Because the K+/ H antiporter moves K into a cell which needs to be then reabsorbed into blood

Question 33

What happens with B cells to repair alkalosis

Answer 33

HCO passively moved to the lumen to be excreted and H+ is actively transported via H/K antiporter back to ecf

Question 34

What happens to the K in alkalosis B cells

Answer 34

K is then excreted when it’s moved into cell via antiporter