Why can the lungs, consisting of muscle tissue, change their volume?

The lungs are able to change their volume. This is how gas exchange occurs between the body and the environment. The lungs cannot move on their own. The change in volume occurs due to a change in pressure in the chest. Pressure changes due to the work of many muscle groups. The rib cage expands or shrinks. At the same time, the pressure inside the lungs changes. This is how air gets in and out. This process is controlled by the medulla oblongata at an unconscious level. Therefore, we do not forget to breathe in our sleep.