What are the four processes of respiration? be sure to define ventilation?

Respiration is an catabolic process in which the organic compounds are oxidized to release energy, carbon dioxide and water. The liberated energy is stored in the ATP molecules (adenosine triphosphate), which are the energy currency of the cells. The four basic processes involved in respiration are-

(1) Pulmonary ventilation or breathing - It is the process of inflow of air into the lungs from the atmosphere (inspiration or inhalation) and outflow of air from the lungs to the atmosphere (expiration or exhalation). It is due to the difference in the air pressures according to the principle of Boyle's law.

(2) External respiration - It is the process of exchange of the oxygen and carbon dioxide between the inhaled air in the alveoli of the lungs and the deoxygenated pulmonary blood.

(3) Internal respiration - It is the process of exchange of gases between the oxygenated blood and the tissue cells of the body.

(4) Cellular respiration - It is the process of oxidation of the respiratory substrates like glucose inside the cells.

Thus, the four processes of respiration include the pulmonary ventilation, external respiration, internal respiration and cellular respiration.