CO2 diffuses more easily through the respiratory membrane than O2 because it is:
**Core Concept**
The respiratory membrane is a thin layer of tissue that separates the alveoli from the capillaries. It is composed of type I pneumocytes, capillary endothelial cells, and a thin layer of connective tissue. The movement of gases across this membrane is primarily determined by the partial pressures of the gases on either side and the solubility of the gases in the blood.
**Why the Correct Answer is Right**
CO2 diffuses more easily through the respiratory membrane than O2 because it is more soluble in blood. This is due to the presence of carbonic anhydrase, an enzyme that catalyzes the rapid conversion of CO2 to bicarbonate ions (HCO3-). This reaction increases the concentration of CO2 in the blood, allowing it to diffuse more easily across the respiratory membrane. Additionally, the partial pressure of CO2 is higher in the alveoli than in the blood, which also facilitates its diffusion.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided.
**Option B:** This option is not provided.
**Option C:** Not applicable, as the correct answer is not listed.
**Clinical Pearl / High-Yield Fact**
The rate of gas diffusion across the respiratory membrane is influenced by both the partial pressures of the gases and their solubility in blood. Carbonic anhydrase plays a crucial role in increasing the solubility of CO2 in blood, allowing it to diffuse more easily across the respiratory membrane.
**Correct Answer:** Not provided in the options, however, the most likely answer would be **C. It is more soluble in blood.**