Exchange Substances

Question 1

How are the lungs adapted for exchanging substances?

Answer 1

The function of the lungs is to transfer oxygen to the blood and to remove waste carbon dioxide from it.
To do this the lungs contain millions of little air sacs called alveoli where gas exchange takes place. The alveoli are specialised to maximise the diffusion of oxygen and carbon dioxide. They have:
-An enormous surface area (about 75m-squared in humans).
-A moist lining for dissolving gases.
-Very thin walls.
-A good blood supply.

Question 2

How is the small intestine adapted for exchanging substances?

Answer 2

The inside of the small intestine is covered in millions and millions of these tiny little projections called villi.
They increase the surface area in a big way so that digested food is absorbed much more quickly into the blood.
They have:
-A single layer of surface cells
-A very good blood supply to assist quick absorption.