GENERAL HISTOLOGY

Detailed explanation-1: -The layer of moisture in the alveoli allows gases to dissolve so that they can diffuse quickly. The alveoli have a very large total surface area and a very good blood supply, provided by the dense network of capillaries that surround them.

Detailed explanation-2: -The alveoli present in the lungs have thin walls composed only of a single layer of cells in order to minimize the diffusion distance. Their walls are moist which helps the gases to diffuse better. They are richly supplied with blood capillaries to ensure the efficient exchange of gases with the bloodstream.

Detailed explanation-3: -The small round alveoli allow for an amazingly large surface area for this gas exchange to take place. Remember, the blood capillaries must be in contact with the respiratory surface for gas exchange to take place. Therefore, the greater the surface area, the more gas exchange can occur.

Detailed explanation-4: -The walls of capillaries are extremely thin. This property allows nutrients and oxygen to travel through the bloodstream and diffuse into the tissues. As a result, waste materials can diffuse out of tissues into the bloodstream and be carried to the lungs, where they can be re-oxygenated.