Respiratory Physiology V

Question 1

What are the three means of carbon dioxide transport in the blood and what percentage do each of these contribute to the amount of carbon dioxide overall?

Answer 1

1. In solution - 10%.
2. As bicarbonate - 60%.
3. As carbamino compounds - 30%.

Question 2

What Law does the amount of carbon dioxide dissolved in solution follow?

Answer 2

Henry’s Law - the amount of a gas dissolved in solution is proportional to the partial pressure of the gas with which the liquid is in equilibrium.

Question 3

How many times more soluble is carbon dioxide than oxygen?

Answer 3

20 times.

Question 4

What is the equation for bicarbonate formation from carbon dioxide and water?

Answer 4

CO2 + H2O H2CO3 H+ + HCO3-.

Question 5

What enzymes mediates the formation of carbonic acid from carbon dioxide and water during the process of bicarbonate formation? Where does this occur?

Answer 5

Carbonic anhydrase.

Occurs in red-blood cells.

Question 6

Summarise bicarbonate formation in terms of the events that happen in a red blood cell.

(Three steps.)

Answer 6

1. Carbon dioxide diffuses into cell and reacts with water (mediated by carbonic anhydrase) to form carbonic acid, which breaks down into the hydrogen ion and bicarbonate.
2. Bicarbonate exchanged across the red blood cell membrane for chlorine (bicarbonate out for chlorine in).
3. Hydrogen ions form can bind to haemoglobin to form HbH.

Question 7

How are carbamino compounds formed?

Answer 7

Combination of carbon dioxide with terminal amine groups in blood proteins.

Question 8

What part of haemoglobin does carbon dioxide tend to combine with?

Answer 8

Globin.

Question 9

Does the formation of carbamino compounds need an enzyme?

Answer 9

No, it is rapid even without an enzyme.

Question 10

Can reduced haemoglobin bind more or less carbon dioxide than oxyhaemoglobin?

Answer 10

More.

Question 11

Describe the Haldane effect.

Answer 11

The removal of oxygen from haemoglobin increases its ability to pick up carbon dioxide and carbon dioxide generated hydrogen ions.

Question 12

What do the Bohr effect and Haldane effect work in synchrony to facilitate?

Answer 12

Oxygen liberation and uptake of carbon dioxide/carbon dioxide generated hydrogen ions at tissues.

Question 13

What does the Haldane effect mean in terms of the carbon dioxide dissociation curve?

Answer 13

Oxygen shifts the carbon dioxide dissociation curve to the right.

i.e. at low partial pressure of oxygen, carbon dioxide concentration is increased.

Question 14

What does the binding of oxygen to haemoglobin at the lungs mean for its ability to bind other components?

Answer 14

Its ability to bind other components weakens - carbon dioxide and hydrogen ions.