Which part of the diaphragm action contributes to pulling air into the lungs?

The mechanism by which the diaphragm pulls air into the lungs involves contraction and flattening. When the diaphragm contracts, it moves downward and flattens, increasing the volume of the thoracic cavity. This expansion creates a negative pressure within the lungs relative to the outside atmosphere, allowing air to flow in through the airways. This process is essential for inhalation, as it efficiently draws air into the lungs to facilitate gas exchange.

Understanding the role of the diaphragm in respiration is critical. The other potential answers do not accurately describe the active mechanism of inhalation: relaxation implies a return to its resting position without aiding air intake, expansion is a result of pressure changes but does not specify the action of the diaphragm, and movement is a vague term that lacks the specificity of the physiological process involved in breathing.