Arteries are muscular blood vessels that carry blood away from the heart. All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood.The circulatory system is extremely important for sustaining life. Its proper functioning is responsible for the delivery of oxygen and nutrients to all cells, as well as the removal of carbon dioxide and waste products, maintenance of optimum pH, and the mobility of the elements, proteins and cells of the immune system. In developed countries, the two leading causes of death, myocardial infarction and stroke each may directly result from an arterial system that has been slowly and progressively compromised by years of deterioration. (See atherosclerosis).
The arterial system is the higher-pressure portion of the circulatory system. Arterial pressure varies between the peak pressure during heart contraction, called the systolic pressure, and the minimum, or diastolic pressure between contractions, when t