What role does the diaphragm play in the respiratory system?

The diaphragm plays a crucial role in the respiratory system by aiding in the process of breathing. It is a dome-shaped muscle located at the base of the thoracic cavity that separates the chest from the abdominal cavity. When the diaphragm contracts, it moves downward, increasing the volume of the thoracic cavity. This decrease in pressure allows air to flow into the lungs, effectively facilitating inhalation.

Upon relaxing, the diaphragm returns to its domed shape, resulting in a decrease in thoracic volume, which pushes air out of the lungs, aiding in exhalation. This rhythmic contraction and relaxation of the diaphragm is essential for normal breathing, making it a primary muscle involved in the respiratory process. The other options listed do not accurately describe the function of the diaphragm within the context of respiration.