Answer:
Oxygen diffuses across cell membranes into cells, where it is taken into the mitochondria and used as a hydrogen acceptor during the production of ATP to produce water.
Oxygen begins its journey in the human body when we breathe. It passes into the lungs (along with all the other gases in the air) and diffuses across the alveoli of the lungs and into the red blood cells where it binds to hemoglobin. Four oxygen molecules will bind to each hemoglobin molecule. From there, it is pumped throughout the body and performs its life-giving function. Without oxygen, we would not exist. Marie