Lecture 7-CO2 in the blood

Question 1

Which equation summarises the reactions of CO2 in the blood?

Answer 1

CO2 + H20 = H+ + HCO3-

Question 2

What is the Henderson Hasselbach equation for CO2 and HCO3-?

Answer 2

pH=pK + Log ( [HCO3-] / (pCO2 x 0.23) )

0.23 is the solubility factor for CO2

Question 3

Which enzyme speeds up the reaction involving CO2 and HCO3-?

Answer 3

Carbonic anhydrase

Question 4

Which transporter moves HCO3- out of RBCs?

Answer 4

Chloride bicarbonate exchanger

Question 5

True or false: Hb has a large capacity for binding H+

Answer 5

TRUE

Question 6

What controls the concentration of HCO3- in plasma?

Answer 6

Kidneys

Question 7

How do the kidneys control the concentration of HCO3- in plasma?

Answer 7

By varying excretion

Question 8

What happens when venous blood, carrying CO2, reaches the lungs?

Answer 8

• Hb is in the R state after picking up O2 and it gives up the extra H+ it picked up from tissues
• H+ + HCO3- -> CO2 which is breathed out

Question 9

In which 3 forms can CO2 be transported?

Answer 9

• dissolved
• as HCO3-
• as carbamino compounds

Question 10

What are carbamino compounds?

Answer 10

CO2 binds to amine groups on the globin of Hb

Question 11

What is the function of carbamino compounds?

Answer 11

More carbamino compounds formed at tissues because pCO2 higher there and unloading of O2 facilitates binding of CO2 to Hb which is then transported to the lungs