What happens to the diaphragm during expiration?

During expiration, the diaphragm relaxes and returns to its dome-shaped position. This is a crucial part of the breathing process, where the diaphragm, a muscle that separates the thoracic cavity from the abdominal cavity, plays a significant role in regulating airflow in and out of the lungs.

When you exhale, the diaphragm moves upwards, allowing the chest cavity to decrease in volume. This decrease in volume leads to an increase in pressure inside the thoracic cavity compared to the atmospheric pressure, which helps push air out of the lungs. The dome shape of the diaphragm during this phase is essential for assisting in the expulsion of air, as it creates a pressure differential that facilitates airflow.

In contrast, during inhalation, the diaphragm contracts and flattens. However, during expiration, since the diaphragm relaxes and assumes its natural dome shape, the air is pushed out of the lungs effectively. This process is integral to normal respiratory function, reflecting the diaphragm's dynamic role in both inhalation and exhalation.