NREMT Advanced EMT

Answer - B - The alveoli are the structures in the lungs that allow exchange of oxygen and carbon dioxide between the lungs and blood vessels called capillaries. The alveoli are grape-like structures surrounded by many thin blood vessels call capillaries. Gases in the alveoli and capillaries move by diffusion across the thin cell membranes. Carbon dioxide in the blood tends to diffuse into the lungs for removal. Oxygen diffuses out of the alveoli and into blood within the capillaries.