L4 Cardiovascular System 9 20 12 Slide 1 The Cardiovascular System Slide 2 The Cardiovascular System The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products Transport of substances such as o Oxygen and nutrients to cells o Wastes from cells to liver and kidneys o Hormones immune cells clotting proteins to specific target cells Closed system of the heart and blood vessels o The heart pumps blood Main tissue Accessories arteries veins atrioles and capallaries o Blood vessels allow blood to circulate to all parts of the body Blood is used for delivery Slide 3 Overview of the Cardiovascular System The Heart main organ o Located in the thoracic cavity o Diaphragm separates abdominal cavity from throsacic cavity o Size of fist o Weighs approximately 250 350 grams o Valves present for unidirectional blood flow o Four chambers 2 atria and 2 ventricles Double pump Blood vessels Blood Slide 4 Properties of Cardiac Muscle Intercalated discs o Gap junctions so heart contracts as a unit uniform contraction o Desmosomes resist stress the force is so great that they would break apart if they weren t held tightly together Aerobic muscle uses oxygen No cell division after infancy growth by hypertrophy 99 contractile cells 1 autorhythmic cells o Self beating o Electrical o Set beat of heart at 100 beats min and then the endocrine system and nervous system fix it Slide 5 The Heart 4 Chambers Right and left side act as separate pumps Septa separates chambers Interventricular septum o Separates the two ventricles Four chambers o Atria are receiving chambers o Ventricles are discharging chambers Right atrium Left atrium Right ventricle Left ventricle Not a lot of musculature from atria to ventricles therefore not a lot of pressure so you don t need many protective cells Left ventricle most musculature because it pumps systematically which is far Slide 6 The Heart Valvues Allow blood flow in only one direction to prevent back flow o Four valves Atrioventricular AV valves are between atria and ventricles Bicuspid mitrial valve left side of heart Tricuspid valve right side of heart o Semilunar vavles are between ventricle and artery Pulmonary semilunar valve Aortic semilunar valve Slide 7 The Heart Valves AV valves o Anchored in place by chordae tendineae heart strings Have to stay anchored because the valves are very flimsy o Open during heart relaxation and closed during ventricular contraction Semilunar valves o Closed during heart relaxation but open during ventricular contraction These valves operate opposite of one another to force a one way path of blood through the heart complementary Slide 8 Valves and Unidirectional Blood Flow Pressure within chambers of heart vary within heartbeat cycle Pressure difference drive 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 Slide 9 Blood Vessels Vasculature Heart arteries arterioles capillaries venules veins heart Arteries are relatively large braching vessels that conduct blood away from the heart Arterioles are small branching vessels with igh resistance Capillaries are the sit 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 Pressure drives blood Slide 10 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 lings and lungs to heart even though the pulmonary atery is an artery it carries deoxygenated blood Supplied by left heart Blood vessels from heart to systemic tissues and tissues to o Systemic circuit heart Left ventricle venae cava right atrium right ventricle pulmonary artery pulmonary circuit pulmonary veins left atrium left ventricle Slide11 Oxygenation of Blood Exchange between blood an tissue takes place in capillaries Pulmonary capillaries o Blood entering lungs deoxygenated blood o Oxygen diffuses from tissue to blood o Blood leaving lungs oxygenated blood Systemic capillaries o Blood entering tissues oxygenated blood o Oxygen diffuses from blood to tissue o Blood leaving tissues deoxygenated blood Slide 12 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 consists of o Coronary arteries branch from the aorta to supply the heart muscle with oxygenated blood o Cardiac veins drain the myocardium of blood o Coronary sinus a large vein on the posterior of the heart receives blood from cardiac veins Blood empties into the right atrium via the coronary veins Bypass surgery o If you catch a clot in the coronary artery soon enough you can use another artery usually from leg to bypass the clot The heart itself must have its own blood supply Slide 13 Differences Between Blood Vessels Walls of arteries are the thickest Lumens of veins are larger Larger veins have valves to prevent backflow Skeletal muscle squeezes blood in veins toward the heart Walls of capillaries are only one cell layer thick to allow for exchanges between blood and tissue See Table with described above o Vein bring blood to heart and store blood therefore it must be able to strech o Artery does not stretch because the blood has to be transferred it must hold up under high pressure Slide 14 Blood Vessels Microscopic Anatomy Three layers tunics o 1 Tunica intima endothelium intima inside o 2 Tunica Media Smooth muscle Controlled by sympathetic nervous system Radius can be altered May be used to control blood flow to individual capillary beds Used to regulate mean arterial pressure o 3 Tunica externa is mostly fibrous connective tissue Slide 15 Arteries Rapid transpor pathway large diameter little resistance Walls contain elastic and fibrous tissue under high pressure Major arteries Smooth muscle regulates radius o Aorta leaves left ventricle o Pulmonary arteries leave right ventricle Slide 16 Capillaries Site if exchange between blood and tissue o Gas exchange small oxygen and carbon dioxide Substances exchanged due to concentration gradients Carbon dioxide and other wastes leave the cells Oxygen and
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