BBC3 年
Structure and function of the gas exchange system
The oxygen molecules are carried in red blood cells. The exchange of these two gasses occurs by a process called diffusion. Alveoli are tiny air sacs in the lungs where gas is exchanged during ...
BBC4 年
How do substances get into, out of and around our bodies?
Oxygen will diffuse from a high concentration at the alveoli in the lungs, to a lower concentration in the red blood cells. This is a passive process, which means it does not need energy.