The respiratory system takes in oxygen and removes carbon dioxide. It includes the lungs, trachea, larynx, diaphragm, alveolus, and bronchus. The lungs extend throughout the chest cavity and supply oxygen to the body. The diaphragm works with the lungs by pulling down to create space for the lungs to expand and bring in air. The trachea is a pipe that carries air to the lungs. The larynx contains the vocal cords and allows substances to pass into the lungs. The alveolus are tiny air sacs in the lungs that carry oxygen and deliver it to red blood cells. The bronchus branches in the lungs and conduct air into the lungs.