What gas is expelled from the lungs during exhalation?

During exhalation, carbon dioxide is the primary gas that is expelled from the lungs. This process is a critical part of respiration, where the body removes waste products generated during cellular metabolism. When oxygen is inhaled into the lungs, it is delivered to the bloodstream and transported to cells throughout the body for energy production. In return, cells produce carbon dioxide as a byproduct, which enters the bloodstream and is carried back to the lungs.

When the diaphragm and intercostal muscles relax, pressure changes in the thoracic cavity allow carbon dioxide to be pushed out of the lungs and into the atmosphere as the individual exhales. This exchange not only regulates the body’s oxygen and carbon dioxide levels but also supports overall respiratory function.