The function of the cardiovascular system is to deliver oxygen and nutrients and to remove BSCI202 EXAM REVIEW 2 CARDIOVASCULAR SYSTEM The Cardiovascular System carbon dioxide and other waste products Transport of substances such as o Oxygen nutrients to cells o Wastes from cells to liver kidneys o Hormones immune cells clotting proteins to specific target cells A closed system of the heart and blood vessels o The heart pumps blood o Blood vessels allow blood to circulate to all parts of the body Blood is used for delivery Overview of the Cardiovascular System The heart o Located in thoracic cavity o Diaphragm separates abdominal cavity from thoracic cavity o Size of fist o Weights about 250 350 grams o Valves present for unidirectional bloodflow o 4 chambers 2 atria and 2 ventricles blood vessels blood The heart location is in the thorax between the lungs in the inferior mediastinum orientation o pointed apex directed toward left tip o base points toward right shoulder Properties of Cardiac Muscle Intercalated Discs o Gap junctions so heart contracts as a unit o Desmosomes resist stress Aerobic muscle No cell division after infancy growth by hypertrophy 99 contractile cells 1 autorhythmic cells The Heart s Covering The Pericardium pericardium is a double walled membranous sac surrounding heart o o fibrous pericardium is loose and superficial serous pericardium is deep to the fibrous pericardium and composed of 2 layers visceral pericardium next to heart also known as epicardium parietal pericardium outside layer that lines the inner surface of the fibrous pericardium o serous fluid fills the space between the layers of pericardium o lubricates heart decreasing friction o pericarditis inflammation of pericardium Walls of the Heart 3 layers o 1 Epicardium o 2 Myocardium outside layer this layer is the visceral pericardium connective tissue layer 1 middle layer mostly cardiac muscle o 3 Endocardium inner layer endothelium o walls of ventricles thicker than walls of atria o wall of left ventricle thicker than wall of right ventricle The Heart 4 chambers right and left side act as separate pumps septa separates chambers interventricular septum separates the 2 ventricles o o interatrial septum separates the 2 atria 4 chambers o atria are receiving chambers right atrium left atrium o ventricles are discharging chambers right ventricle left ventricle The Heart Valves 4 valves allow blood to flow in only one direction to prevent backflow o atrioventricular AV valves are between atria and ventricles o Bicuspid mitral valve left side of heart o Tricuspid valve right side of heart Semilunar valves are between ventricle and artery o Pulmonary semilunar valve o Aortic semilunar valve AV valves o Anchored in place by chordae tendineae heart strings o Open during heart relaxation and closed during ventricular contraction These valves operate opposite of one another to force a one way path of blood through the heart Valves and Unidrectional Blood Flow Pressure within chambers of heart vary with heartbeat cycle Pressure difference drives blood flow high pressure to low pressure Normal direction of flow o Veins to atria o Atria to ventricles o Ventricles to arteries Valves prevent backward flow of blood All valves open passively based on pressure gradient AV Valves Open Operation of the AV valves o 1 Blood returning to the atria puts pressure against AV valves the AV valves are forced open o 2 As the ventricles fill AV valve flaps hang limply into ventricles o 3 Atria contract forcing additional blood into ventricles 1 Ventricles contract forcing blood against AV valve flaps 2 AV valves close 3 Chordae tendineae tighten preventing valve flaps from everting into atria AV Valves Closed Semilunar Valves 2 operation of semilunar valves o as ventricles contract and intraventricular pressure rises blood is pushed up against semilunar valves forcing them open o as ventricles relax and intraventricular pressure falls blood flows back from arteries filling the leaflets of semilunar valves and forcing them to close Blood Vessels Vasculature heart arteries arterioles capillaries venules veins pressure drives blood flow arteries are relatively large branching vessels that conduct blood away from the heart arterioles are small branching vessels with high resistance capillaries are the site of exchange between blood and tissue venules are small converging vessels veins are relatively large converging vessels that conduct blood to the heart closed system Series Flow Through the Cardiovascular System parallel flow within the systemic or pulmonary circuit o pulmonary circuit supplied by right heart blood vessels from heart to lungs and lungs to heart o systemic circuit supplied by left heart blood vessels from heart to systemic tissues and tissues to heart cardiovascular system closed system left ventricle aorta systemic circuit venae cavae right atrium right ventricle pulmonary artery pulmonary circuit pulmonary veins left atrium left ventricle Oxygenation of Blood exchange between blood and tissue takes place in capillaries capillaries o blood entering lungs deoxygenated blood o oxygen diffuses from tissue to blood o blood leaving lungs oxygenated blood capillaries o blood entering tissues oxygenated blood o oxygen diffuses from blood to tissue o blood leaving tissues deoxygenated blood Blood Flow Through the Heart superior and inferior venae cavae lead blood into the right atrium from right atrium through the tricupid valve blood travels to the right ventricle from the right ventricle blood leaves the heart as it passed through the pulmonary semilunar valve into the pulmonary trunk oxygen is picked up and carbon dioxide is dropped off by blood in lungs oxygen rich blood returns to the heart through the 4 pulmonary veins pulmonary trunk splits into right and left pulmonary arteries that carry blood to the lungs blood enters the left atrium and travels through the bicuspid valve into the left ventricle from the left ventricle blood leaves the heart via the aortic semilunar valave and aorta Coronary Circulation intrinsic conduction system nodal system heart muscle cells contract without nerve impulses in a regular continuous way blood in the heart chambers does not nourish the myocardium the heart has its own nourishing circulatory system consisting of o o coronary arteries branch from the aorta to supply the heart muscle with oxygenated blood cardiac veins drain the myocardium of blood 3 o coronary sinus a
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