Question

Non-polar and lipid-soluble substances cross the blood-brain barrier rapidly via diffusion. Which of the following substances can cross the blood-brain barrier rapidly?

1) O2
2) CO₂

Answer 1

Non-polar and lipid-soluble substances like O2 and CO2 can cross the blood-brain barrier rapidly via diffusion.

Step-by-step explanation:

Non-polar and lipid-soluble substances, such as O2 and CO2, can cross the blood-brain barrier rapidly via diffusion. The structure of the lipid bilayer in the cell membrane allows these small, uncharged substances to pass through easily. Since oxygen and carbon dioxide are both non-polar gases, they can diffuse through the lipid bilayer and move down their concentration gradient without requiring any energy on the part of the cell.