What is the main role of the diaphragm in respiration?

The diaphragm plays a crucial role in respiration primarily through its ability to contract, which creates a negative pressure within the thoracic cavity. When the diaphragm contracts, it moves downward and flattens, increasing the volume of the chest cavity. This increase in volume leads to a decrease in pressure relative to the atmospheric pressure outside the body, causing air to be drawn into the lungs. The diaphragm is the primary muscle of inspiration and is vital for normal breathing.

While other processes like the exchange of gases, maintaining blood flow, and protecting the lungs are essential for overall respiratory health, these functions do not represent the diaphragm's main role in the mechanics of breathing. Thus, its function of contracting to facilitate airflow into the lungs is key to understanding how respiration occurs.