How do our lungs work
We breathe by drawing air into our lung (inhaling) and letting it out again (exhaling)
Every time we breathe, a fresh supply of air makes contact with the lung with tissue which contains blood. In the lung,blood and air exchange some of the gases they contain.
The lung fill both sides of the chest. The lung tissue is like a sponge in some ways. The space, or air sacs, are pockets where the air is received. The gases which are needed are taken in, and the unwanted gases are forced out. The air sacs are separated from each other by very thin walls filled with very fine blood vessels called capillaries. Only a few cells separate the blood from the air, so gases can pass easily through these thin walls.
The lung are elastic, which means they can stretch. When we breathe in, the chest gets bigger and the lung expand with it. Then air rushes in through the nose,mouth and throat to the air sacs of the lungs. When we breathe out, the space inside the chest becomes smaller. The lungs partly close and the air is forced out again.
How much air can the lungs hold? The lungs of an adult man can probably hold about seven pints of air;those of a woman , about five prints.
The lungs are never empty , even when you try hard to force the air out. The amount of air remainning after exhaling with great force is called "residual air"
When we inhale we mix fresh air with this residual air.
Breathing goes on regularly even when we don't think about it, or when we are asleep. But we can stop breating for a short time if we want to, as when we hold our breath when we are under water.