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Respiratory System

The diaphragm is the musculomembranous partition separating the abdominal and thoracic cavities which serves as the primary muscle aiding inhalation. [1][2] The diaphragm's function is to help pump the carbon dioxide out of the lungs and pull the oxygen into the lungs. As the diaphragm contracts and relaxes, breathing takes place. When the diaphragm contracts, oxygen is pulled into the lungs. When the diaphragm relaxes, carbon dioxide is pumped out of the lungs. Exhalation is primarily a passive process, but during forced or active exhalation, as when blowing out a candle, expiratory muscles including the abdominal muscles and internal intercostal muscles, generate abdominal and thoracic pressure, which forces air out of the lungs.[3] The diaphragm is also involved in non-respiratory functions: helping to expel vomit, feces, and urine from the body by increasing intra-abdominal pressure, and preventing acid reflux by exerting pressure on the esophagus as it passes through the esophageal hiatus.[4]


  1. Dorland's Medical Dictionary for Health Consumers (2007). Diaphragm. Free Retrieved on 2008-10-01.
  2. unk. (n.d.). Respiratory Disorders Glossary. Retrieved on 2008-10-01.
  3. various (n.d.). Respiratory System. Wikipedia. Retrieved on 2008-10-02.
  4. various (n.d.). Thoracic Diaphragm. Wikipedia. Retrieved on 2008-10-02.