Describe how air is moved in to and out of your lungs.

The process of moving air into and out of your lungs is called ventilation, or breathing. Ventilating the lungs is brought about by the contraction and relaxation of the intercostal muscles and the diaphragm, this causes changes in pressure in the chest cavity forcing air into and out of the lungs. This can be broken down into steps for both breathing in and breathing out. Breathing in: The ribs move up and out as the intercostal muscles contract and the diaphragm contracts and flattens, this increases the volume of the chest cavity. The increased volume creates a lower pressure in the chest meaning that atmospheric air is at a higher pressure, causing air to be drawn into the lungs.Breathing out: The ribs fall (move in and down) and the diaphragm relaxes, causing the volume of the chest to decrease. Decreased volume causes a pressure increase in the chest cavity so the pressure in the chest is higher than the atmospheric air pressure, forcing air out of the lungs.