PHYS: CO2 Transport and Acid-Base

Question 1

What are the 3 mechanisms for CO2 transport in the blood?

Answer 1

Dissolved CO2 (5-10%)
Protein carbamylation (10-20%)
Formation of Bicarbonate (80-90%)

Question 2

What is the rate-limiting step of bicarbonate production?

Answer 2

H2O + CO2 –> H2CO3

Question 3

True or false: carbonic anhydrase is present in plasma.

Answer 3

FALSE: present in RBCs (CO2 and H2CO3 can diffuse/be transported across surfaces)

Question 4

How does HCO3- get back into plasma after forming in RBCs?

Answer 4

Hamburger’s phenomenon: band 3 protein is an anion exchange protein that takes Cl- (and water) in for every HCO3- out

Question 5

What happens to H+ ions in RBCs?

Answer 5

buffered by deoxyhemoglobin

Question 6

What are the main differences between CO2 dissociation and O2 dissociation curves?

Answer 6

CO2 curve is:

• Hgiher
• No cooperativity (linear)
• Much steeper

Question 7

What is the Bohr effect?

Answer 7

when H+ binds to hemoglobin (acidosis) it decreases the affinity for oxygen–shifting curve to right and causing oxygen release

Question 8

pH depends on the ratio of what two values?

Answer 8

HCO3- / Pco2

Question 9

Hypoventilation causes what respiratory acid/base condition?

Answer 9

acidosis (retention of CO2)

Question 10

Hyperventilation causes what respiratory acid/base condition?

Answer 10

alkalosis (loss of CO2)