Thx a lot 🙏 Plssss I'm struggling with this doubt if the gaz molecules are dissolving into the liquid how come pressure( partial pressure in gaz phase) doesn't decrease ( as there's less molecules so less pressure) ?
Great question! Your thinking is correct. Technically--in controlled / closed conditions--as air molecules move from the gas phase to the liquid phase, the pressure *would* decrease. However, in the context of respiratory physiology, the gasses in question are atmospheric (or from a compressed air source in certain clinical situations). This means that the amount of air molecules moving to the liquid phase is negligible compared to the total number of molecules in the gas phase (thus the simplification of assuming no change in air / gas-phase pressure). Hope that helps!
@@houriak848 Whoops--it appears I was a little too hasty with my reply. It should be: when the air molecules move from gas phase to liquid phase. My apologies for this. I will edit the comment accordingly.
@@PeteMeighan actually I thought about it I find it weird that this amount that moved is able to change partial pressures of gases O2, CO2 in blood but there's no change in alveolus
@@houriak848 That's because the rate of O2 entering the alveolar spaces (via ventilation) Is equal to the rate it enters the blood (via gas exchange). For CO2, the rate leaving the blood (via gas exchange) is equal to the rate leaving the alveolar spaces (via ventilation).
My confusion part is that why the partial pressure of the low solubility gas in gaseous phase and liquid phase are still the same even though the concentration of that gas in liquid phase is lower than that in the gaseous phase. Is that when it reach equilibrium rate, so the partial pressure is the same between the two phases? But why different concentration of gases in the two phases do not affect the partial pressure?
Because of equilibrium.. Be it low or high solubility, once the system reaches equilibrium, the amount of molecules entering and exiting would be equal isnt it?
