Heart and lungs, computer artwork. The heart (centre) is a hollow muscle that pumps blood around the body. Blood collects oxygen in the lungs (purple), air-filled sacs in either side of the chest cavity. Arteries, such as the carotid arteries in the neck and the subclavian arteries beneath the collar bones (upper centre), carry oxygenated blood away from the heart to the body's tissues. Deoxygenated blood is returned from the body to the heart in veins, for example the jugular veins (from the head), and subclavian veins (beneath the collar bones).