Question

how does oxygen enter the blood stream? the alveoli allows oxygen to diffuse to the capillaries. oxygen does not enter the blood stream. the cilia in the nose catch the oxygen. capillaries in the nose absorb the oxygen from the air.

Explanation:

Oxygen enters the bloodstream through the alveoli in the lungs. Alveoli are tiny air - sacs where oxygen diffuses across a thin membrane into the surrounding capillaries. Cilia in the nose help filter air but not absorb oxygen. Capillaries in the nose are not the main site for oxygen absorption. And it is known that oxygen does enter the bloodstream for respiration.

Answer:

The alveoli allows oxygen to diffuse to the capillaries.