To begin with, moisture is a very important feature for living organisms. In humans, the inner lining of lungs is coated with a thin flim of moisture. This is because:
- moisture will speed up the rate of diffusion of gases as the gases will dissolve in the moisture and will go down the concentration gradient to the other side. (O2 will diffuse inside the RBCs while CO2 will diffuse out)
- the thin flim of moisture will act as a lubricant when the lungs expand and contract. This will allow the lungs to inflate and deflate without the "walls" sticking to each other
the land animals accomplish this by:
- intake of water in their diet, water will eventually lubricate most of the body internally
- breathin in will cause water vapours to be inhaled, in some cases they may condense inside the lungs (water from lungs can evaporate also)
- moisture will speed up the rate of diffusion of gases as the gases will dissolve in the moisture and will go down the concentration gradient to the other side. (O2 will diffuse inside the RBCs while CO2 will diffuse out)
- the thin flim of moisture will act as a lubricant when the lungs expand and contract. This will allow the lungs to inflate and deflate without the "walls" sticking to each other
the land animals accomplish this by:
- intake of water in their diet, water will eventually lubricate most of the body internally
- breathin in will cause water vapours to be inhaled, in some cases they may condense inside the lungs (water from lungs can evaporate also)
