Human Body

Inhalation

When we breathe in air, the process is called inhalation, and the air we breathe in is called inhaled air. When we breathe out, it is called exhalation, and that air is called exhaled air. Respiration is the overall process of breathing, and circulation refers to blood moving through the body. So inhalation specifically means breathing in.

Oxygen

Our lungs absorb oxygen gas from the inhaled air and send it to the blood. The blood then carries oxygen to all parts of the body. Carbon dioxide is the gas that the body gives back — it comes out when we exhale. Nitrogen is present in air but the body does not use it for breathing. Ammonia is a harmful gas, not something we absorb from breathing.

It contracts and moves downward

When we breathe in (inhale), the diaphragm contracts and moves downward. This increases the space in the chest cavity, so the lungs can expand and fill with air. When we breathe out (exhale), the diaphragm relaxes and moves upward, making the chest cavity smaller and pushing air out of the lungs. The diaphragm never stays still during breathing — it moves with every breath.

Liver

Internal organs are those that are present inside the body and cannot be seen from outside. The liver is an internal organ. Ears, nose, and knees are external organs — they are on the outside of the body and we can see them. Other examples of internal organs include the brain, heart, stomach, lungs, intestines, and kidneys.