Vita Kbv

The cardiovascular system is concerned with the transport of blood and lymph through the body. It may be divided into four major components: the heart, the macro-circulation, the microcirculation and the lymph vascular system.
	Essentially, the macro-circulation comprises all vessels, both arteries and veins, which would be visible to the eye. The vessels of the macro-circulation supply and drain a network of fine vessels interposed between them, the capillaries. This network is also called the capillary bed. Water and other components of the blood plasma which exude from the blood vessels form the interstitial fluid, which is returned to the circulation by the 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. Vessels close to the heart (aorta, pulmonary trunk and the larger arteries that originate from them) are elastic arteries.