Lecture 3: O2/CO2 Blood Transport

Question 1

How is arterial O2 transported?

Answer 1

1. Dissolved in RBC cytosol/plasma
2. Reversibly bound to RBC hemoglobin (98%)

Question 2

What part of oxygen (or other gases) in blood contribute to partial P?

Answer 2

Only dissolved O2 contributes to PO2

Question 3

What is hemoglobin saturation when blood leaves tissue capillaries at rest?

Answer 3

75% saturation Hb; much more O2 delivery capacity available when demand goes up

Question 4

Factors that decrease Hb affinity for O2

Answer 4

Right shifts caused by:
- 2,3-DPG (BPG)
- Increasing temperature
- Increasing acidity
- CO2, H+ allosteric effects

Question 5

Effect of CO on hemoglobin

Answer 5

CO removes cooperativity from Hb and binds Hb with 200X affinity vs O2. Additionally, Hb affinity for O2 increases; O2 binding is competitively inhibited and O2 delivery is inhibited.

Question 6

How is CO2 transported in the blood?

Answer 6

• 10% dissolved in blood
• 25-30% on Hb amino groups (carbaminohemoglobin)
• 60-65% converted to bicarb by carbonic anhydrase

Question 7

H+ affinity for hemoglobin

Answer 7

DeoxyHb has&raquo_space; affinity for H+ vs HbO2

Question 8

Henry’s Law for dissolved gases

Answer 8

[dissolved] = P_gas x solubility

Question 9

CO2 solubility vs O2 soluility

Answer 9

CO2 is 24X more soluble in blood compared to blood

Question 10

Bicarb/Cl- exchanger

Answer 10

Exports bicarb and imports Cl- to maintain macro electroneutrality. Increased CO2 -> more acid; RBCs need to deal with this acid and prevent rxn backflow as deoxyHb picks up protons

Question 11

Where does expired CO2 come from?

Answer 11

More of expired CO2 comes from Hb carbaminos

Question 12

Haldane effect

Answer 12

Deoxy-blood carries more CO2 vs oxy-blood due to more deoxyHb meaning more carbamino sites available