QS Study

Pulmonary Ventilation is the inflow and outflow of air between the atmosphere and the lung per minute. This system, also known as the ventilation system, meets the body’s needs for gas exchange at the lungs and at the tissues.

Alveolar Ventilation is the total volume of new air enters into the alveoli and other gas exchange areas of lungs (alveolar sacs, alveolar ducts, and respiratory bronchioles) in each time. It is the process by which oxygen is brought into the lungs from the atmosphere and by which the carbon dioxide carried into the lungs in the mixed venous blood is expelled from the body.

Difference between pulmonary and alveolar ventilation – Pulmonary refers to the total exchange, whereas alveolar refers to the effective ventilation of the alveoli, where gas exchange with the blood takes place.

Pulmonary ventilation

  1. The inflow and outflow of air between the atmosphere and the lungs per minute are called pulmonary ventilation.
  2. Pulmonary ventilation = Tidal volume X respiratory rate = 500 x 12 = 6000 ml/ min.
  3. Importance: It provides Oxygen to the tissues and removes Carbon dioxide from the tissue.
  4. It is the volume of air breathed in and out in one minute. It is the total product of tidal volume and the respiratory rate. The average tidal volume is 500 ml/breath and an average respiratory rate is 12 breath/min.

Fig: Pulmonary ventilation

Alveolar ventilation

  1. The total volume of new air enters into the alveoli and other gas exchanges areas of lungs in each minute.
  2. Alveolar ventilation = Respiratory rate x (Tidal volume – dead space volume)

= 12 x (500 – 150) ml = 12 x 350 ml = 4200 ml

  1. Importance: It is one of the major factors determining the conc. of Carbon dioxide and Oxygen in the alveoli.
  2. It is the volume of air exchanged between the atmosphere and the alveoli in one minute. Alveolar ventilation is more important than the pulmonary ventilation. In alveolar ventilation, the anatomic dead space should be taken into an account.
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