please answer?

Asked by  | 21st Jul, 2010, 10:20: PM

Expert Answer:

Each lung contains 300-350 million small balloon like thin structures called alveoli. These alveoli are surrounded by many blood capillaries. Alveoli are the sites of exchange of gases. These alveoli increase the surface area for gaseous exchange, making the process of respiration more efficient.

Answered by  | 23rd Jul, 2010, 10:44: AM

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