Answer:
1. The isothermic saturation boundary
2. Located 5 cm below the carina
Explanation:
The isothermic saturation boundary is the point where the inspired air becomes fully saturated with water vapor and is warmed to the body temperature (37 degrees Celsius).
Mostly, the isothermic saturation boundary is present just 5 cm below the carina. The exact position of the isothermic saturation boundary keeps on changing depending on several factors such as air temperature and humidity, mouth breathing, etc.
The turbulent convection efficiently warms the inspired air and the mucosal lining imparts water vapor to the warmed up inspired air by the process of evaporation.
The process of warming and humidification ends when the inspired air becomes 100% saturated with water vapor at the body temperature.
