RESP 120 Chapter 9: CO2 Equilibrium & Transport

What percentage of CO₂ is transported dissolved in plasma?

~5–10%.

What percentage of CO₂ is transported bound to proteins (carbamino compounds)?

~20%.

What percentage of CO₂ is transported as bicarbonate (HCO₃⁻)?~

70%.

Which form of CO₂ transport determines PaCO₂ on an ABG?

Dissolved CO₂ in plasma.

What is carbaminohemoglobin?

CO₂ bound to amino groups on hemoglobin.

What is the primary form of CO₂ transport in the blood?

Bicarbonate (HCO₃⁻).

What enzyme catalyzes the CO₂–bicarbonate reaction?

Carbonic anhydrase.

What is the CO₂–bicarbonate equilibrium reaction?

CO₂ + H₂O ⇋ H₂CO₃ ⇋ H⁺ + HCO₃⁻

What happens to hydrogen ions (H⁺) produced in RBCs during CO₂ transport?

They bind to hemoglobin and are buffered.

What is the chloride shift (Hamburger phenomenon)?

HCO₃⁻ leaves the RBC and is replaced by Cl⁻ to maintain electrical neutrality.

What is the Haldane effect?

Oxygen binding to hemoglobin promotes the release of CO₂ and H⁺ in the lungs.

How does hypoventilation affect PaCO₂?

PaCO₂ increases, causing respiratory acidosis.

How does hyperventilation affect PaCO₂?

PaCO₂ decreases, causing respiratory alkalosis.

What part of the brain regulates ventilation in response to CO₂?

The medulla oblongata.

What primarily stimulates the respiratory center to change ventilation?

Changes in PaCO₂ (via pH changes in CSF).