Emission meaning in biology?

expelling, discharge, emission - any of several bodily processes by which substances go out of the body; "the discharge of pus" nocturnal emission - ejaculation during sleep (usually during a dream)

Explanation:

i believe it would be the lungs.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.