From which organ does oxygen diffusion into the blood occur in the oxygen transport system?

From which organ does oxygen diffusion into the blood occur in the oxygen transport system?

• A. Lungs
• B. Heart
• C. Muscles
• D. Brain

Answer: (A)

Oxygen diffusion into the blood occurs in the lungs, at the alveolar-capillary interface. Here, oxygen moves from the air in the tiny alveoli into the blood because the partial pressure of O2 is higher in the alveolar air than in the blood. The thin respiratory membrane between alveoli and pulmonary capillaries allows this diffusion, and the oxygen then binds to hemoglobin in red blood cells for transport to tissues. The heart pumps that oxygenated blood, while muscles and the brain use it once it’s carried there.

Oxygen diffusion into the blood occurs in the lungs, at the alveolar-capillary interface. Here, oxygen moves from the air in the tiny alveoli into the blood because the partial pressure of O2 is higher in the alveolar air than in the blood. The thin respiratory membrane between alveoli and pulmonary capillaries allows this diffusion, and the oxygen then binds to hemoglobin in red blood cells for transport to tissues. The heart pumps that oxygenated blood, while muscles and the brain use it once it’s carried there.