Every time you breathe, your diaphragm tightens and moves downward. This ups the space inside your chest cavity, and your lungs can safely expand in the roomier surroundings. (The muscles of the rib cage also contract along with the diaphragm.) When you breathe out, the space in your chest cavity shrinks, forcing air out of your lungs. Many people believe that the inflation and the deflation of their lungs is what causes their chests to move up and down with each breath, but in fact it is the contraction and release of the diaphragm that causes this motion.
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Key Facts In This Video
All living cells get their energy through a process called cellular respiration. 00:38
Without oxygen, brain cells lack the energy necessary to communicate. 02:00
Plants break down glucose using oxygen and cellular respiration to get the energy they need to grow. 02:36