Breathing

The diaphragm, a powerful muscle located beneath the lungs, causes the lungs to inflate.  This inflation draws air into the alveoli through the trachea, bronchi and bronchioles.  The diaphragm then causes the lungs to deflate, pushing deoxygenated air out of the lungs. Breathing is characterised by two processes: inhalation (breathing in) and exhalation (breathing out).  It is important to note that breathing is not the same as respiration, but merely a part of the system.