Gene models

Question 1

Where does the afferent arteriole feed into?

Answer 1

Glomerular capillaries into Bowmans capsule via glomerular filtration

Question 2

Where does the efferent arteriole feed into?

Answer 2

Peritubular capillaries to venous blood and renal tubule via tubular secretion

Question 3

Describe tubular reabsorption

Answer 3

Solutes are removed from the lumen of the tubule into peritubular capillaries and then into the circulation

Question 4

Describe tubular reabsorption

Answer 4

Ions from peritubular capillary are moved into the renal tubule

Question 5

What tubule does filtrate move out of the bowmans capsule into the nephron by?

Answer 5

The proximal tubule

Question 6

What does filtration restrict?

Answer 6

Blood cells and proteins passing through the membrane

Question 7

Describe ultrafiltrate

Answer 7

Protein free plasma in bowmans capsule

Question 8

Which direction does transcellular reabsorption happen in?

Answer 8

From the lumen of the tubule to peritubular capillary

Question 9

Which direction does transcellular secretion occur?

Answer 9

From peritubular capillary to the lumen of tubule

Question 10

Which direction does paracellular secretion or reabsorption occur?

Answer 10

In both directions from lumen of tubule to peritubular capillary

Question 11

How much filtrate does the proximal tubule reabsorb?

Answer 11

70% H2O and Na+
100% of glucose and amino acids
90% HCO3-

Question 12

What is the function of NaPi2 in the proximal tubule?

Answer 12

Net reabsorption of phosphate

Question 13

Function of SGLT1 and SGLT2 in proximal tubule?

Answer 13

Na/glucose cotransporters
Cause reabsorption of glucose

Question 14

What issues arise when NaPi2 is knocked out?

Answer 14

Less phosphate reabsorption
More phosphate in urine
Leads to renal mineralisation

Question 15

What occurs due to renal mineralisation?

Answer 15

Calcium phosphate deposits in the kidney
Hypophosphatemia

Question 16

What would increased phosphate tubular fluid lead to in wild type mice?

Answer 16

Increased calcification
Intraluminal stones (nephrolithiasis)
Deposits renal parenchyma (nephrocalcinosis)

Question 17

What protein helps maintain body fluid pH?

Answer 17

NHE3
Sodium hydrogen exchange protein

Question 18

Describe the mechanism of NHE3

Answer 18

Exchanges sodium for hydrogen in the apical membrane ->
Uses a conc and potential diff gradient ->
Sodium in the cell, hydrogen out

Question 19

What happens to the H+ pumped into the apical membrane by NHE3?

Answer 19

Hydrogen + HCO3- -> H2CO3
Carbonic acid reacts with carbonic anhydrase to form CO2 and H2O
H2O is reabsorbed

Question 20

What happens upon removal of NHE3?

Answer 20

Bicarbonate is lower than normal ->
cannot maintain pH of body fluids which impacts the heart and electrically excitable cells

Question 21

Define maximum transport

Answer 21

All transport proteins are being used at maximum rate

Question 22

What molecule shouldn’t be seen in healthy urine?

Answer 22

Glucose