Question

1. Where is air almost completely humidified?

   	A.	In the nose
   	B.	In the lungs
   	C.	In the alveoli
   	D.	In the trachea

question 1

Answer 1

Let me first explain to you about basics of humidification.

During inspiration ,well vascularised mucous membranes inside the nose and mouth release moisture to the passing respiratory gases.as a result ,a healthy adult person evaporates 200 to 300ml of water per day.While inspiring through nose or mouth the mucous membrane cool down.

During exhalation this cooling effect causes a portion of moisture in the air coming from the lungs(100 percent relative humidity)to condensate on the mucous membranes,whereby mucous membranes are moisturised again.

On the way to lower respiratory tract ,the respiratory gas already humidified in nasopharyn is conditioned further until isothermal saturation limit is reached.

Isothermal saturation limit means the maximum possible humidity at a given temperature,which amounts to 100 percent relative humidty and 44mg absolute humidity at 37 degree celcius.

A healthy breathing person reaches this equikibrium during nasal breathing at the bifurcation of trachea .Hence only water vapor satiated and body warm air reaches alveoli.

I am drawing an image for further clarification

so your answer is IN THE TRACHEA.