What happens to the thoracic cavity during contraction of the diaphragm?

During contraction of the diaphragm, the volume of the thoracic cavity increases. The diaphragm is a dome-shaped muscle that sits at the base of the thoracic cavity. When it contracts, it flattens and moves downward, which enlarges the thoracic cavity. This increase in volume reduces the pressure within the thoracic cavity relative to the atmospheric pressure outside the body.

As a result, air is drawn into the lungs to equalize the pressure difference, facilitating inhalation. The mechanics of respiratory physiology explain that an increase in volume leads to a decrease in pressure, allowing for efficient breathing. Understanding this relationship is crucial for grasping the mechanics of respiration and the role the diaphragm plays in ventilating the lungs.