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
Active transport in the human body
Active transport is used in the gut when there is a low concentration of nutrient
in the gut, but a high concentration in the blood.
When there is a lower concentration in the gut and the nutrients need to enter the
blood then active transport allows the nutrients to travel against the concentration