Why does your chest go up and down while breathing?

Your chest rises and falls during breathing due to the movement of the diaphragm and intercostal muscles. When you inhale, the diaphragm contracts and moves downward, while the intercostal muscles expand the rib cage, increasing the volume of the thoracic cavity and allowing air to flow into the lungs. Conversely, when you exhale, the diaphragm relaxes and the rib cage contracts, pushing air out of the lungs. This rhythmic movement is essential for gas exchange in the body.