Oxygen enters the bloodline in the

Bronchi
Pharynx
Larynx
Alveoli

1 answer

Oxygen enters the bloodstream primarily in the alveoli. The alveoli are tiny air sacs in the lungs where gas exchange occurs; oxygen from the air inside the alveoli diffuses into the blood in the surrounding capillaries, while carbon dioxide from the blood is expelled into the alveoli to be exhaled.