Which process involves the relaxation of intercostal muscles and diaphragm to reduce the size of the chest cavity?

The process that involves the relaxation of intercostal muscles and the diaphragm to reduce the size of the chest cavity is exhalation. During exhalation, the diaphragm, which is a dome-shaped muscle at the base of the thoracic cavity, relaxes and moves upward, while the intercostal muscles between the ribs also relax. This results in a decrease in the volume of the thoracic cavity, which causes air to be pushed out of the lungs.

As the volume of the chest cavity decreases, the pressure inside the lungs becomes greater than the atmospheric pressure, leading to the expulsion of air. This is a vital part of the respiratory cycle, allowing for the removal of carbon dioxide-rich air and the preparation for the next inhalation phase, where fresh oxygen is brought into the lungs.

Other processes mentioned, such as inhalation, involve the active contraction of the diaphragm and intercostal muscles to increase chest cavity volume and draw air in, while diffusion refers to the movement of gases across membranes and circulation pertains to the transportation of blood throughout the body.