Question

1) Sponges have internal surface area with lots of tiny holes to hold water.Our lungs are not very big, so how can they have large internal surface area?

2) Why do our lungs need to have a internal surface area?

Answer 1

1)There are small air sacks in our lungs called Alveoli . These are very small and very thin. These alveoli increase the surface area of the lungs.
2).The rate of oxygen diffusion is dependent on surface area, so gas exchange occurs more quickly with larger surface areas. hence the lungs require a large surface area.