L17 (pk7) - Carriage of CO2/ H+

Question 1

How can CO2 be carried in the blood?

Answer 1

1. Physically dissolved as CO2 (exerting partial pressure) (5% total as dissolved)
2. Bound to proteins as carbamino compounds (in plasma and RBC) (5% total as amine groups)
3. As bicarbonate ion HCO3- (90% total as HCO3-)

Question 2

What are the ‘waste’ products of metabolism?

Answer 2

1. 0.16g H2O per min
2. 1.22 kcal heat per min
3. 200ml CO2 per min

Question 3

What are the differences between the CO2 diss curve andthe O2 diss curve?

Answer 3

1. Content of each gas held in body is different - at any partial pressure of gases, there are more CO2 in blood than O2
2. The shape (sigmoid v linear)
3. Haldane vs Bohr effect (both effects are of physiological importance for blood gas carriage in the lungs and peripheral tissues)

Question 4

What are the 2 factors that account for the Haldane effect?

Answer 4

1. Deoxy Hb is 3.5x more effective at binding CO2 than oxyHb

2. Deoxy Hb binds H+ more avidly than HbO2