ANATOMY

Detailed explanation-1: -The cells in our bodies need oxygen to stay alive. Carbon dioxide is made in our bodies as cells do their jobs. The lungs and respiratory system allow oxygen in the air to be taken into the body, while also letting the body get rid of carbon dioxide in the air breathed out.

Detailed explanation-2: -respiration and breathing | AMNH. Most living things need oxygen to survive. Oxygen helps organisms grow, reproduce, and turn food into energy. Humans get the oxygen they need by breathing through their nose and mouth into their lungs.

Detailed explanation-3: -Gases we Breathe In We all are aware that our atmosphere is a mixture of gases and it contains 78% nitrogen, 21% oxygen, 1% argon, 0.04% carbon dioxide, 0.5% water vapour. When we breathe in, we inhale the same mixture of gases contained in the atmosphere as our nose cannot filter out the oxygen from other gases.