Acid Base Metabolism

Question 1

How can H+ be taken out of a cell?

Answer 1

1. Via Sodium proton antiporter (to filtrate, NOT capillaries)
2. Via H+ ATPase
3. Hydrogen potassium ATPase

Question 2

How can HCO3- be taken out of a cell?

Answer 2

1. Chloride bicarbonate exchanger

2. Sodium bicarbonate cotransporter

Question 3

Describe HCO3- reabsorption

Answer 3

1. CA on apical membrane converts filtrate HCO3- to H20 and CO2.
2. H2O and CO2 diffuse in, and CA converts it back into H+ and HCO2-. Then the transporters transport HCO3- and H+ in opposite directions

Question 4

What are the 2 types of intercalating cells of collecting duct?

DIFFERENCE IS THE SAME TRANPSORTERS OCCUR ON OPPOSITE SIDES OF THE MEMBRANE

Answer 4

1. Acid secreting cell (a cell). Secrete acid to filtrate

2. Bicarbonate secreting cell (B cell). Secrete bicarbonate to filtrate

Question 5

What are the 2 isoforms of carbonic anhydrase?

Answer 5

1. CA 4 on the apical membrane/outside

2. CA 2 inside the cell

Question 6

How else can HCO3- be generated in cells?

Answer 6

Breakdown of amino acids. (e.g. glutamine -> NH4+ and HCO3-

Question 7

What are the acute and chronic mechanisms of respiratory acidosis?

Answer 7

Acute: intracellular buffering

Chronic: HCO3- generation and more ammonium secretion

Question 8

Acute and chronic compensatory mechanisms for respiratory alkalosis?

Answer 8

Acute: intracellular buffering

Chronic:
decrease HCO3- and decrease ammonium generation

Question 9

Low proton concentration in kidney. What could it be?

Answer 9

IF BICARBONATE LOSS IS PRIMARY DISTURBANCE, METABOLIC ACIDOSIS.

IF BICARBONATE LOSS IS COMPENSATORY MECHANISM, RESPIRATORY ALKALOSIS