Gene models Flashcards
Where does the afferent arteriole feed into?
Glomerular capillaries into Bowmans capsule via glomerular filtration
Where does the efferent arteriole feed into?
Peritubular capillaries to venous blood and renal tubule via tubular secretion
Describe tubular reabsorption
Solutes are removed from the lumen of the tubule into peritubular capillaries and then into the circulation
Describe tubular reabsorption
Ions from peritubular capillary are moved into the renal tubule
What tubule does filtrate move out of the bowmans capsule into the nephron by?
The proximal tubule
What does filtration restrict?
Blood cells and proteins passing through the membrane
Describe ultrafiltrate
Protein free plasma in bowmans capsule
Which direction does transcellular reabsorption happen in?
From the lumen of the tubule to peritubular capillary
Which direction does transcellular secretion occur?
From peritubular capillary to the lumen of tubule
Which direction does paracellular secretion or reabsorption occur?
In both directions from lumen of tubule to peritubular capillary
How much filtrate does the proximal tubule reabsorb?
70% H2O and Na+
100% of glucose and amino acids
90% HCO3-
What is the function of NaPi2 in the proximal tubule?
Net reabsorption of phosphate
Function of SGLT1 and SGLT2 in proximal tubule?
Na/glucose cotransporters
Cause reabsorption of glucose
What issues arise when NaPi2 is knocked out?
Less phosphate reabsorption
More phosphate in urine
Leads to renal mineralisation
What occurs due to renal mineralisation?
Calcium phosphate deposits in the kidney
Hypophosphatemia
What would increased phosphate tubular fluid lead to in wild type mice?
Increased calcification
Intraluminal stones (nephrolithiasis)
Deposits renal parenchyma (nephrocalcinosis)
What protein helps maintain body fluid pH?
NHE3
Sodium hydrogen exchange protein
Describe the mechanism of NHE3
Exchanges sodium for hydrogen in the apical membrane ->
Uses a conc and potential diff gradient ->
Sodium in the cell, hydrogen out
What happens to the H+ pumped into the apical membrane by NHE3?
Hydrogen + HCO3- -> H2CO3
Carbonic acid reacts with carbonic anhydrase to form CO2 and H2O
H2O is reabsorbed
What happens upon removal of NHE3?
Bicarbonate is lower than normal ->
cannot maintain pH of body fluids which impacts the heart and electrically excitable cells
Define maximum transport
All transport proteins are being used at maximum rate
What molecule shouldn’t be seen in healthy urine?
Glucose
