Question

What is the pressure of the gas within the alveoli at the peak of inspiration, just before expiration, relative to the atmospheric air?

a. Greater than atmospheric air

b. Less than atmospheric air

c. The same as atmospheric air

d. None of the above

- Is it true that alveolar ventilation (L/min) is typically lower volume than pulmonary ventilation?

Answer 1

The pressure of the gas within the alveoli at the peak of inspiration, just before expiration, is greater than atmospheric air.

The mechanism of breathing works on the principle of pressure gradient. Air alawys flows down the pressure gradient, that is, air flows from an area of higher pressure to an area of lower pressure.

At the peak of inspiration, pressure of the gas inside the alveoli becomes greater than the atmospheric pressure, therefore, the air flows out of the lungs during expiration.

Yes, it is true that alveolar ventilation (L/min) is typically lower volume than pulmonary ventilation as alveolar ventilation is to the amount of gas that reaches the alveoli during a breath whereas Pulmonary ventilation is the total volume of gas taken into the respiratory system during a breath.

Basically, pulomary ventilation= alveolar ventilation + dead space ventilation.