ABSTRACT
The cardiovascular system consists of three components: the heart, the blood, and the blood vessels. The heart behaves as a hydraulic pump, creating the driving force behind the pulsatile blood flow through the arterial system. In contrast, the systemic circulatory system acts as a parallel circuit, and the distribution of blood to each of the body organs varies, depending on the relative resistance of the arterioles and capillaries preceding the organ system. The heart is enclosed within the pericardium, a thin but tough connective tissue sheath. It provides protection and anchoring of the heart within the chest cavity, as well as acts as a constraint that prevents the overfilling of the heart chambers. The heart muscle is made up of cardiac muscle cells connected by intercalated discs. The arteries move blood away from the heart and, with the exception of the pulmonary artery, carry oxygenated blood. The capillaries are thin-walled and form the site of gas exchange within the tissues.
