THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -Oxygen is inhaled into the lungs and passes through the alveoli (the tiny air sacs at the end of the bronchioles ) and into the bloodstream (see inset), where it travels to the tissues throughout the body.

Detailed explanation-2: -When we breathe in, the millions of air sacs in the lungs fill with fresh oxygenated air. The oxygen then moves into the blood by passing first through the very thin walls of the air sacs and then into the capillaries, which are tiny blood vessels in a network within the lungs.