what is active transport?
where substances need to be moved from an area of high concentration to an area of low concentration against a concentration gradient.
NEEDS ENERGY--- this comes from cellular respiration
two situations it happens in:
- against a concentration gradient
- when a molecule is too large to move through the particually-permiable membrane
How are your lungs adapted to make gas exchange as
they have ALVEOLI which are adapted to make it as efficient as possible
o2 into blood by diffusion thin alveoli walls to make it as easy as possible
co2 out by diffusion moist so it can disolve
large surface area