What diffuses from the air in the alveoli into the blood?Multiple Choiceoxygencarbon dioxidewaternitrogenAll of the answer choices diffuse from air into blood.

Answer

In the alveoli of the lungs, the primary gases that diffuse from the air into the blood are oxygen ($O_2$) and carbon dioxide ($CO_2$).

1. Oxygen Diffusion: When we inhale, oxygen present in the alveoli diffuses across the alveolar membrane into the bloodstream. This process occurs because of the concentration gradient—the concentration of oxygen is higher in the alveoli than in the deoxygenated blood in the pulmonary capillaries.

2. Carbon Dioxide Diffusion: Conversely, carbon dioxide, which is a waste product of cellular metabolism, diffuses from the blood into the alveoli. This occurs because carbon dioxide concentration is higher in the blood than in the alveoli, allowing it to be expelled during exhalation.

3. Water and Nitrogen: Water vapor can also be present in the air and may slightly diffuse, but it is not a major component in the gas exchange process. Nitrogen does not significantly diffuse in the context of gas exchange between the alveoli and blood, as its partial pressure remains relatively stable.

Final Answer

The correct answer is oxygen and carbon dioxide. However, since the question includes a choice stating "All of the answer choices diffuse from air into blood," the most appropriate choice based on typical biological understanding would be oxygen as the primary gas diffusing into the blood from the alveoli.