The diaphragm muscle sits below the lungs and continuously expands and contracts. What happens in the chest cavity as a result of this expansion and contraction?

When the diaphragm contracts, it moves downward and expands the chest cavity, lowering the air pressure inside so air flows into the lungs. When it relaxes, the chest cavity gets smaller and pressure rises, pushing air out. Therefore, the diaphragm’s movement causes a change in air pressure.

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