To understand the mechanism of breathing.
Breathing is taking air in and out to exchange oxygen for carbon dioxide with the help of respiratory organs. Taking the air in is known as inhalation, whereas exhaling the air out is called exhalation. It is a continuous process that occurs all the time and throughout an organism's life.
The human respiratory system consists of a pair of lungs and a series of airways that leads to the lungs. The lungs are a pair of spongy organs lying in the chest cavity formed by the ribs. The whole respiratory tract consists of the nose, pharynx, larynx, trachea, bronchi, bronchioles, diaphragm, and ribs. The human respiratory system starts from the mouth and nose, pulling the air to pharynx. It is a part that passes the air between the larynx and trachea. The larynx delivers the air from the mouth and nose to the trachea. The trachea is a passage connected to the throat and lungs, and bronchial tubes at the bottom of the trachea are attached to both lungs. The muscles called the diaphragm, which helps the lungs to pull the air in and out, and the bones that surround the lungs called ribs which protects the lungs and heart.
We usually breathe with the help of our nostrils. When we breathe, the air passes into the nasal cavity through the nostrils. The lungs are in the chest cavity, and the ribs are around the cavity on both sides. Breathing requires the diaphragm and rib cage to move. During the inhalation, the ribs move upwards, and the diaphragm moves down. The movement increases the space in the chest cavity, so the air enters the lungs. During the exhalation process, the ribs move down, and the diaphragm back to its position. It reduces chest cavity size. So, the air is coming out from the lungs.