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 The walls of alveoli are very thin and diffusion of gases takes place through these
walls.
 Alveoli have a rich supply of blood through a dense network of capillaries present
around them.
 Function of Alveoli-The alveoli provide a larger surface area for easy and faster
exchange of gases.

Lungs

 Lungs are the main respiratory organs and are located on both sides of the chest
cavity.
 Lungs are pink in colour and spongy due to the presence of air spaces and a
large number of blood capillaries filled with blood.
 The lungs are protected in the rib cage and supported by large flat muscle at the
floor of the chest cavity called diaphragm.

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