Answer:
The lungs
Step-by-step explanation:
The lungs in your body get filled up with air when you inhale. There are blood vessels around the alveoli in your lungs (which are tiny air sacs that hold the air). The blood vessels absorb the oxygen in a process called diffusion where gas diffuses through the one cell thick wall of the alveoli into the blood vessels. The circulatory system then pumps the blood around your body to the cells that need the oxygen.