Gas Transport

Question 1

Function of Hb in O2 absorption in the blood from the alveoli.

Answer 1

O2 is not very soluble in the blood and Hb allows oxygen remain in the blood.
Also O2 bound to Hb does not contribute to the partial pressure of O2 in the blood and this allows a larger gradient promoting O2 diffusion from the alveoli into the blood.

Question 2

How many mL of O2 can bind 1 gram of Hb?

Answer 2

about 1.34 mL of O2

Question 3

How is the Percent Saturation of Hb calculated?

Answer 3

% = (O2 bound to Hb/maximum capacity of Hb to bind O2) x 100

Max capacity = 1.34mL O2/gHb x (___) grams Hb/100mL blood

Question 4

What effect does anemia have on O2 carrying capacity and % hemoglobin saturation?

Answer 4

Decreases carrying capacity

No effect on Saturation

Question 5

What effect does polycythemia have on O2 carrying capacity and % hemoglobin saturation?

Answer 5

Increases carrying capacity

No effect on Saturation

Question 6

What effect does: CO, CO2, H+, and BPG have on the affinity of Hb for O2?

Answer 6

CO increases the affinity of Hb for O2 (left shift)

The rest decrease the affinity (right shift)

Question 7

What is the significance of the chloride shift in CO2 transport?

Answer 7

When CO2 is released from tissues
CO2 combines with water using carbonic anhydrase to form bicarbonate while in a RBC. In order for the bicarb to be released from the cell it passes thru a bicarb/Cl- antiport.

When a RBC needs to release the CO2 into an alveolus the antiport runs in reverse to bring bicarb back in to form CO2 and water again allowing the CO2 to be sent into the airway.
(this is not the only mechanism of transportation of CO2, some just always stays bound to Hb in the RBCs)

Question 8

What is the Haldane Effect?

Answer 8

Low O2 increases Hb affinity for CO2

-the opposite is true