20.2.1 pressure differentials and gradients

pressure differential

the difference in pressure between any 2 spaces that are occupied by a gas (or fluid), independent of whether or not the gas can move between the spaces

• things go from high to low pressyre

pressure gradient between atmosphere and alveoli

can shift between

pressure gradient between alveolar and pleural spaces

cannot shift since there’s no pathway between alveoli and pleural space, no gradient

amount of gas particles

if the number of gas particles in a given volume increases, the pressure increases

temperature

if the temperature increases while all other factors remain the same, pressure increases

volume of space

if the volume increases while all other factors stay the same, pressure decreases

atmospheric pressure

760 mmHg

• pressure in the atmosphere that surrounds the body

interpulmonary/alveolar pressure

pressure in the alveoli

when the diaphragm contracts, the alveolar pressure is low since the volume is high, so the air would flow in (inspiration)

intrapleural pressure

pressure in the space between the visceral and parietal pleura

partial pressure

• represents the contribution of any gas in a mixture to the mixture’s total pressure

• total pressure x fraction of gas