Blinking and breathing are two functions that are attributable to these nerves. This system involves the heart, blood vessels and blood . The heart is the pump that drives the circulation of the blood around the body. The body's blood vessels are quite complicated, and include arteries , which take the blood from the heart, and veins , which return the blood to the heart. There are smaller blood vessels such as arterioles, venules and capillaries , most of which are located at the body's extremities and usually close to the skin.
Blood is the medium that transports oxygen from the respiratory system to the body's cells.
As the heart pumps blood a pulse beat can be felt at various locations in the body, and each pulse beat corresponds to one heartbeat. The heart rate of the average adult at rest is between 60 to 100 beats per minute, depending on age, medical conditions and general fitness. The most accessible pulse points are the radial and carotid arteries. A working knowledge of the locations of these pulse points is essential for the first aid provider. This system is composed of the airway and the lungs .