Kidney function 5 Flashcards
What is normal plasma value for the arterial partial pressure of CO2
5.3 kPa
What is normal plasma value for arterial/venous [HCO3-]
25mM
What is plasma pH proportional to? What controls them
pH == [HCO3-]/[pCO2]
hco3 dealt with in kidneys, co2 by lungs
Describe the physiology of the renal H+ excretion
H2CO3 dissociates into H+ and HCO3-
The H+ diffuses out into lumen and joins with HPO42- and is excreted, HCO3- diffuses into blood
What enzyme produces H2CO3 from H20 and CO2
Carbonic anydrase
How does the kidney add HCO3- to plasma via glutamine
Glutamine brought into cell via Na+ cotransport, it is metabolised into NH4+ and HCO3-
Ammonium secreted and HCO3- added to blood
Describe pCO2 and [HCO3-] in resp. alkalosis
Low CO2, no change
Describe pCO2 and [HCO3-] in resp. acidosis
High CO2, no change
Describe pCO2 and [HCO3-] in non resp acidosis
no change in CO2, bicarbonate low
Describe pCO2 and [HCO3-] in non resp alkalosis
no change in CO2, bicarbonate high
What is a normal value for pCO2 in arteries
5.3kPa
What is a normal arterial [HCO3-]
25 mM
What is a normal arterial [HCO3-]
25 mM
At what pH do proteins (His residues) ionise
~6
At what pH does ammonia ionise
9.2
At what pH does phosphate ionise
6.8
At what pH does bicarbonate ionise
6.1
At what pH does urate ionise
5.8
At what pH does citrate ionise
5.5
What is the usual range for pH of urine
4.4-8
Where does bicarbonate reabsorption occur
Prox tubule
Asc loop of henle
Cortical collecting ducts
(intercalated cells type A)
What transporter is involved in NH4+ secretion
Na+:NH4+ exchanger
What is metabolic alkalosis caused by
repeated vomiting
excess aldosterone
excess alkali ingestion
What is pendrin
Found in type B intercalated cells of collecting duct
Excretes HCO3-
What does the liver do in response to acidosis
increased glutamine production
What does the liver do in response to alkalosis
decreased glutamine production
