There are two stages to breathing: inhalation and exhalation (also known as inspiration and expiration).
Inhalation is an active process where the most important muscle is the diaphragm.
The respiratory tract includes mouth and nose, pharynx, trachea, bronchi and alveoli.
On the surface of the alveoli, gases exchange: oxygen to the bloodstream, carbon dioxide to the exhaled air.
Respiration takes place in two phases. During inhalation, the diaphragm and rib muscles contract → the chest expands → as a result of vacuum, the lungs become inflated. During exhalation, the respiratory muscles relax→ the thoracic cavity shrinks → the air is expelled from the lungs.
Keywords: inhalation and exhalation, diaphragm, trachea, bronchi, pleural membranes, lungs.
