<<Pranayama is the link between the mental and physical disciplines. While the action is physical, the effect is to make the mind calm, lucid and steady''. _Swami Vishnu-devananda
Inhalation: contraction of the diaphragm and the intercostal muscles enlarges the chest cavity, expands the lungs, and causes air to move into the lungs. Exhalation: relaxation of the diaphragm and the intercostal muscles decreases size of the chest cavity, defleats the lungs, and causes air to move out of the lungs. The control of respiration depends on the nervous impulses causing the contrraction (inhalation). When these impulses cease, exhalation occurs.
The rate of breathing is about 7/1minute. It changes with exercise. Respiration is also regulated by chemical controls and respiration reflexes. These reflexes are stimulated by the concentration of oxygen & carbon dioxide in the blood. They accelerate are decrease the rate of respiation.
Pranayama is the methodology to acquire a healthy breathing pattern. The power of respiration is very important; it affects the overall health, pschology and emotions. With a right respiration pattern, one can acquire a lot.