What makes lungs well adapted for gas exchange?

Answer 1

the alveolus

OTHER ANSWER:

The surface area is kept moist to allow the oxygen and the carbon dioxide to pass trough

and large surface area is availeble.

By Fla97

Answer2:

The walls of the alveoli are adapted for efficient gas exchange in the following ways:

(i.)Large surface area. The total surface area of all the alveoli in both the lungs is over 100m2.

(ii.)Thin Walls. Alveolar walls are composed of a single layer of cells called epithelium. The surrounding capillary walls are also one cell thick. So gases need to diffuse only across this small distance to get into the blood.

(iii.)Moist Surface. Special cells in the wall of the alveoli produce a watery fluid so oxygen can dissolve, then diffuse into the blood cells of the capillary.

(iv.)The vast network of capillaries surrounding the alveolus supply blood to continuously carry the oxygen away from, and carbon dioxide to, the alveoli. In red blood cells, the presence of a respiratory pigment called hemoglobin, which combines with oxygen, increase the oxygen carrying ability of blood. The continual removal of oxygen keeps oxygen levels low in the capillaries. This favors rapid diffusion of oxygen from alveolus to blood as a steep diffusion gradient is mantained.

Note: adaptations (i) to (iv) are structural adaptations

(v.)Ventilation of lungs. The constant movement of air in and out of lungs maintains an efficient diffusion gradient for exchange of oxygen and carbon dioxide which takes place between the air and blood capillaries surrounding the alveoli lungs.