Which components move air in and out of the body?

• A. Respiratory pump
• B. Circulatory pump
• C. Digestive pump
• D. Lymphatic pump

Answer: (A)

Air movement is driven by changes in thoracic pressure produced by the breathing muscles, a mechanism often described as the respiratory pump. When the diaphragm contracts and the rib cage expands, the chest cavity volume increases and intrapulmonary pressure falls below atmospheric pressure, drawing air into the lungs. When the muscles relax and the chest cavity returns to its resting size, intrapulmonary pressure rises above atmospheric pressure, pushing air out. This alternating pressure change is what moves air in and out.

The circulatory pump moves blood through the heart, the digestive pump moves food along the digestive tract, and the lymphatic pump helps move lymph; none of these primarily move air.