The cardiovascular system is concerned with the transport of blood and lymph through the body. It may be divided into four major components: heart, macro-circulation, microcirculation and lymph vascular system.
All arterial vessels originate with either the pulmonary trunk (from the right ventricle) or the aorta (from the left ventricle). Specializations of the walls of arteries relate mainly to two factors: the pressure pulses generated during contractions of the heart (systole) and the regulation of blood supply to the target tissues of the arteries. The tunica media is the main site of histological specializations in the walls of arteries.