The Cardiovascular System Of The Heart And The Vasculature

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The cardiovascular system is formed by the heart and the vasculature, a close system of vessels, which include arteries, arterioles, capillaries, venules, veins and lymph vessels.
The heart is located in the mediastinum, about two-thirds from the body midline. Three layers form the heart. From the inside out: endocardium, myocardium and epicardium. The myocardium, the thickest of all, is formed by striated muscle to provide the heart with the contractibility necessary to pump the blood into the vasculature. (Martini, Nath, & Bartholomew, 2008)
The myocardium contains the pacemaker cells that generate electrical impulses to create the heart’s movements. These impulses are triggered by action potentials in the pacemaker cells of the Sinoatrial Node. These are then transmitted to the atria and to the AV node. (Hull & Slegg, 2009)
The heart is divided into four chambers; the superior chambers (atria) receive blood and are connected to the inferior chambers (ventricle), through the atrioventricular valves. Once in the ventricles, blood is ejected to the vasculature through the semilunar valves. These valves, similar to the ones in the veins, ensure the unidirectionality of blood flow.
As with the heart, endothelium provides the internal layer (tunica intima) for all the vasculature.
Apart from the capillaries and venules, which only consist of endothelium, the rest of the vasculature is formed by three layers: tunica intima, tunica media, and tunica adventitia. (Marieb &
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