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As you breathe ( in, out ), the ( diaphragm, intercostal muscles, abdomen ) ( contracts, expands, contract, expand ) and becomes ( flatter, thicker, thinner ), and the ( intercostal muscles, diaphragm, abdomen ) ( contract, expand, contracts, expands ), expanding the ( rib cage, abdomen, lungs, bronchioles ) . This ( increases, decreases ) the volume of the ( thorax, abdomen, bronchioles ), which causes the ( pressure in, surface area of, volume of ) the lungs to ( decrease, increase ) and allows air to be easily drawn in).
When breathing ( out, in ), the ( intercostal muscles, diaphragm, abdomen ) ( relax, contract, relaxes, contracts ), contracting the ( rib cage, abdomen, lungs, diaphragm ), and the ( diaphragm, intercostal muscles, abdomen ) also ( relaxes, contracts, relax, contract ) and moves ( up, down ), increasing the ( pressure in, surface area of, volume of ) the lungs and expelling the air.