Gas exchange in the lungs
The lungs are optimized to ensure that exchange happens efficiently as
possible. In the lungs the two main gases that are exchanged are oxygen
and carbon dioxide. This gas exchange across the Alveoli.
Features of the alveoli
The alveoli are small structures within the lungs which resemble a hollow
bunch of grapes. They help to increase surface area, they have very thin
walls and have a very large blood supply. All these factors help to increase
the rate of diffusion.
Diffusion – the concept of diffusion is very simple – gases move from an area
of high concentration to an area of low concentration.
This illustration will help you understand diffusion. In alveoli the oxygen
moves from the alveoli into the blood for it to be transported around the body.
The carbon dioxide moves from the blood back into the alveoli so it can be
breathed out again.