Assertion: lung's alveoli | /r/RelatedTo | greater surface
Facets:
value: for gas exchange
type: PURPOSE
Source sentences:
text: The smaller alveoli in mammals are associated with a greater surface for gas exchange: although the respiratory surface of the frog (Rana) is about 20 square centimetres per cubic centimetre (50.8 square inches per one cubic inch) of air, that of humans is about 300 square centimetres.