What happens to the thoracic cavity during exhalation?

During exhalation, the thoracic cavity undergoes a contraction in size, primarily due to the relaxation of the diaphragm and the intercostal muscles. This contraction causes the volume of the thoracic cavity to decrease, which in turn exerts pressure on the lungs. As the thoracic cavity gets smaller, the pressure inside the lungs becomes greater than the pressure outside the body, resulting in the air being pushed out of the lungs. This process is essential for effective breathing, allowing carbon dioxide-rich air to be expelled from the respiratory system. Understanding the mechanics of this process highlights the relationship between thoracic cavity volume and lung function during respiration.