66. Intext question XVIII

 

Lungs are the organs that aid in the gaseous exchange. They are also called as pulmonespancreas. They are situated in the thoracic cavitypelvic cavity that facilitates gaseous exchange through the diffusion of gases through alveoli. DiaphragmAlveoli is the primary functional unit of the lung, richly supplied with blood capillaries. They are thin-walled and looks like tiny bubbles within the sacs. In addition, there is the presence of a single layer of epithelial cells.

 

Nearly \(480\) \(million\) alveoli are present in human lungs. The surface area of alveoli is smalllarge and vary around \(100 m^2\). The large surface area and the thin-walled nature of alveolar cells allow gases to diffuse easily across the cellsdoes not allow gases to diffuse easily across the cells. In the alveoli, exchange of gases takes place i.e., oxygen from alveolar air diffuses into blood and carbon dioxide from blood into alveolar air.