Carbon Dioxide Transport

Question 1

What are the forms that CO2 is carried in?

Answer 1

In solution - 7%.
As bicarbonate - 70%.
Carbamino compounds - 23%.

Question 2

What is the PCO2 of arterial and venous blood and how much does the blood carry?

Answer 2

Arterial - 5.3 kPa - 27ml/L.

Venous - 6.0kPa - 31ml/L.

Question 3

What is the CO2 delivery equation?

Answer 3

CO2 delivery = cardiac output x (venous CO2 - arterial CO2).

Question 4

Percentage of CO2 delivered to lungs as dissolved gas in plasma?

Answer 4

10%.

Question 5

Reaction of CO2 as bicarbonate?

Answer 5

CO2 + H2O H2CO3 H+ + HCO3-.

Question 6

What is chloride shift?

Answer 6

Transport of HCO3- ions into the plasma in exchange for Cl-.

Question 7

How are carbamino compounds formed?

Answer 7

CO2 reacts with the -NH2 groups at the N-terminal of polypeptide chains.
R-NH2 + CO2 RNHCOOH.

Question 8

What is the Haldane Effect?

Answer 8

Deoxyhaemoglobin is a weaker acid than oxyhaemoglobin, so more deoxyhaemoglobin means better buffering of H+ ions (since weak acids accept protons better), therefore more CO2 carried.

Question 9

What is glaucoma?

Answer 9

Build up of pressure in the eye due to poor drainage of aqueous humor.

Question 10

What inhibits carbonic anhydrase?

Answer 10

Acetazolamide.

Question 11

What happens if divers raise too quickly?

Answer 11

If diver raises too quickly (rapid depressurisation occurs), and N2 will come out of solution and form bubbles in the blood.
Bubbles normally form in in joint cavities, causing diver to curl up in pain - called The Bends.

Question 12

How to treat The Bends?

Answer 12

Putting patient in pressure container - put N2 back into solution - slowly bring back to normal pressure.