During which phase of respiration does the diaphragm mostly relax?

During exhalation, the diaphragm primarily relaxes, allowing the lungs to deflate and expel air. During this phase, the diaphragm, which is a dome-shaped muscle located at the base of the thoracic cavity, moves upward as it relaxes. This upward movement decreases the volume of the thoracic cavity, leading to an increase in pressure within the lungs, which forces air out of the respiratory system.

In contrast, during inhalation, the diaphragm contracts and moves downward, increasing thoracic volume and allowing air to enter the lungs. The resting phase reflects a state where there is no significant respiratory effort being made, while forced inhalation involves additional muscle activity beyond the diaphragm, such as the use of accessory muscles to further expand the thoracic cavity. Understanding these distinctions helps clarify the mechanics of breathing and the role of the diaphragm throughout the respiratory process.