How does the structure of alveoli maximize gas exchange?

The alveoli are sacks coated on their inner wall by white and sticky liquid, they can be more than a millimeter in diameter and surface active agent. In them there is the exchange of gases between O2 and CO2.

They are evaginations of the epithelium of the air ducts with a single opening for the gases to exit and enter, controlled by the action of a smooth muscle sphincter. Its walls, called alveolar septa, provide a large increase in the exchange surface.

the major parts of the digestive system:

salivary glands.

pharynx.

esophagus.

stomach.

small intestine.

large intestine.

rectum.

accessory digestive organs: liver, gallbladder, pancreas.

the index of refraction of the second medium is higher. i just took the test trust me !