QS Study

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 refers to the amount of gas that reaches the alveoli during a breath. 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.

Alveolar ventilation

Respiratory rate X (tidal volume – dead space volume)

= 12 x (500 – 150) ml = 12 x 350 ml = 4200 ml = 4.2.

Lung Volumes

  • FRC (Functional Residual Capacity) 2.2l.(supine)
  • TLC (Total Lung Capacity) 6.2l.
  • Maximum Inspiratory Volume 4.0l. above FRC.
  • ERV (Expiratory Reserve Volume) 1.0l. below FRC.
  • RV (Residual Volume) 1.2l.
  • MVV (Maximal Voluntary Ventilation) 150 l/m.

High rates of air exchange in functioning alveoli, that is higher alveolar ventilation, would bring in the fresh oxygen-rich air and efflux carbon dioxide-laden air rapidly; consequently, the concentration of oxygen would be higher and the concentration of carbon dioxide would be lower within alveoli.

Function

The function of alveolar ventilation is to eliminate carbon dioxide from the blood and to add more oxygen to the blood so it can attach to hemoglobin and be delivered to body tissues. This happens because gases move according to their absorption gradients, in other words, gas constantly moves to where ever there is less of its self. Since the body’s metabolism is continually removing oxygen from the blood and adding carbon dioxide, the blood has more carbon dioxide and less oxygen than stimulated air.