How does oxygen enters the lungs?

The oxygen travels down your windpipe into your lungs. After it exits through the bronchial tubes, it enters the alveoli, or air sacs. Once it does that, passes to the capillaries (blood vessels).

Air is breathed in, it goes through the pharynx (if you are breathing through your nose), down the trachea (lung pipe), and into the lungs. Air is breathed in, it goes through the pharynx (if you are breathing through your nose), down the trachea (lung pipe), and into the lungs.