CVPR Week 5: Gas Transport III

Question 1

CO₂

Answer 1

CO₂ moves out of the tissues down its concentration gradient into the plasma where it enters RBCs where it is converted into Bicarbonate ions.

Question 2

CO₂ reaction in RBCs and transport reactions/mechanisms

Answer 2

CO₂ +H₂O ← Carbonic Anhydrase → H₂CO₃ ↔ H⁺ + HCO₃^-

And

H+ also binds with Hb to form HHb

H⁺ + Hb^- ↔ HHb

Or

CO₂ binds with Hb to form HbCO₂ (Carbaminohemoglobin)

CO₂ + Hb ↔ HbCO₂

Or

CO2 is dissolved in the plasma

Question 3

Interactions between CO₂ and O₂ transport

Answer 3

• CO2 moves down conc. gradient from the tissues into the blood
• enter the RBC and binds with H2O to form H2CO3 bicarbonate catalyzed by carbonic anhydrase
• Bicarbonate then dissociates into H+ and HCO3- which can equilibrate with the plasma
• since Hb is a proton acceptor in the cell when bound to H+ it reduces Hb’s affinity for oxygen so that way O2 is released by Hb (this accounts for the Bohr effect)

Question 4

Bohr effect

Answer 4

the rightward shift of the Hb O2 dissociation curve resulting from an increase in CO2 and ↓pH

Question 5

Interactions between CO₂ and O₂ transport in the lungs