When a person inhales oxygen fills tiny air sacs in the person's lungs. Next the oxygen moves from these air sacs into small blood vessels that line the lungs and then it moves into the bloodstream so?

The oxygen molecules enter the bloodstream by diffusing through the thin walls of the capillaries that surround the air sacs in the lungs. These capillaries are where the exchange of gases like oxygen and carbon dioxide occurs. The oxygen molecules bind to hemoglobin in red blood cells, and are then transported throughout the body to cells and tissues that need oxygen for energy production.