Question

As the concentration of dissolved CO$_2$ increases in blood, the following happens:

• A. The concentration of HCO$_3^-$ decreases
• B. The concentration of H$^+$ decreases
• C. The blood pH increases
• D. The oxygen transport/delivery is not affected

Hint:

CO$_2$ ↑ → H$^+$ ↑ → pH ↓ (Acidosis). Remember equation: CO$_2$ + H$_2$O ↔ H$^+$ + HCO$_3^-$.

Answer 1

The Correct Option is D

Concept:
Carbon dioxide in blood participates in acid-base balance: \[ CO_2 + H_2O \leftrightarrow H_2CO_3 \leftrightarrow H^+ + HCO_3^- \]

Step 1: Increase in CO$_2$.
When CO$_2$ increases:
• More carbonic acid forms
• Dissociates into H$^+$ and HCO$_3^-$

Step 2: Effect on hydrogen ions.
H$^+$ concentration increases → causes acidosis.

Step 3: Effect on bicarbonate.
HCO$_3^-$ concentration also increases, not decreases.

Step 4: Effect on pH.
Increase in H$^+$ leads to decrease in pH (more acidic).

Step 5: Oxygen transport.
Although CO$_2$ affects hemoglobin affinity (Bohr effect), oxygen transport is not directly stopped; thus option (4) is most appropriate among given incorrect alternatives.

Step 6: Conclusion.
\[ \boxed{\text{The oxygen transport/delivery is not affected}} \]