PowerPoint® Lecture Slides prepared by Barbara Heard, Atlantic Cape Community College C H A P T E R 18 The Cardiovascular System: The Heart: Part A © Annie Leibovitz/Contact Press Images © 2013 Pearson Education, Inc. The Pulmonary and Systemic Circuits • Heart is transport system; two side-by-side pumps – Right side receives oxygen-poor blood from tissues • Pumps to lungs to get rid of CO2, pick up O2, via pulmonary circuit – Left side receives oxygenated blood from lungs • Pumps to body tissues via systemic circuit © 2013 Pearson Education, Inc. Figure 18.1 The systemic and pulmonary circuits. Capillary beds of lungs where gas exchange occurs Pulmonary Circuit Pulmonary arteries Pulmonary veins Aorta and branches Venae cavae Left atrium Left Right ventricle atrium Heart Right ventricle Systemic Circuit Capillary beds of all body tissues where Oxygen-rich, gas exchange occurs CO2-poor blood Oxygen-poor, CO2-rich blood © 2013 Pearson Education, Inc. Heart Anatomy • Approximately size of fist • Location: – In mediastinum between second rib and fifth intercostal space – On superior surface of diaphragm – Two-thirds of heart to left of midsternal line – Anterior to vertebral column, posterior to sternum PLAY Animation: Rotatable heart © 2013 Pearson Education, Inc. Heart Anatomy • Base (posterior surface) leans toward right shoulder • Apex points toward left hip • Apical impulse palpated between fifth and sixth ribs, just below left nipple © 2013 Pearson Education, Inc. Figure 18.2a Location of the heart in the mediastinum. Midsternal line 2nd rib Sternum Diaphragm Location of apical impulse © 2013 Pearson Education, Inc. Figure 18.2c Location of the heart in the mediastinum. Superior Aorta vena cava Parietal pleura (cut) Pulmonary Left lung trunk Pericardium (cut) Apex of heart Diaphragm © 2013 Pearson Education, Inc. Coverings of the Heart: Pericardium • Double-walled sac • Superficial fibrous pericardium – Protects, anchors to surrounding structures, and prevents overfilling © 2013 Pearson Education, Inc. Pericardium • Deep two-layered serous pericardium – Parietal layer lines internal surface of fibrous pericardium – Visceral layer (epicardium) on external surface of heart – Two layers separated by fluid-filled pericardial cavity (decreases friction) © 2013 Pearson Education, Inc. Figure 18.3 The pericardial layers and layers of the heart wall. Pulmonary trunk Fibrous pericardium Parietal layer of serous Pericardium pericardium Myocardium Pericardial cavity Epicardium (visceral layer of serous pericardium) Heart Myocardium wall Endocardium Heart chamber © 2013 Pearson Education, Inc. Homeostatic Imbalance • Pericarditis – Inflammation of pericardium – Roughens membrane surfaces pericardial friction rub (creaking sound) heard with stethoscope – Cardiac tamponade • Excess fluid sometimes compresses heart limited pumping ability © 2013 Pearson Education, Inc. Layers of the Heart Wall • Three layers of heart wall: – Epicardium – Myocardium – Endocardium • Epicardium – Visceral layer of serous pericardium © 2013 Pearson Education, Inc. Layers of the Heart Wall • Myocardium – Spiral bundles of contractile cardiac muscle cells – Cardiac skeleton: crisscrossing, interlacing layer of connective tissue • Anchors cardiac muscle fibers • Supports great vessels and valves • Limits spread of action potentials to specific paths © 2013 Pearson Education, Inc. Layers of the Heart Wall • Endocardium continuous with endothelial lining of blood vessels – Lines heart chambers; covers cardiac skeleton of valves © 2013 Pearson Education, Inc. Figure 18.3 The pericardial layers and layers of the heart wall. Pulmonary trunk Fibrous pericardium Parietal layer of serous Pericardium pericardium Myocardium Pericardial cavity Epicardium (visceral layer of serous pericardium) Heart Myocardium wall Endocardium Heart chamber © 2013 Pearson Education, Inc. Figure 18.4 The circular and spiral arrangement of cardiac muscle bundles in the myocardium of the heart. Cardiac muscle bundles © 2013 Pearson Education, Inc. Chambers • Four chambers: – Two superior atria – Two inferior ventricles • Interatrial septum – separates atria – Fossa ovalis – remnant of foramen ovale of fetal heart • Interventricular septum – separates ventricles © 2013 Pearson Education, Inc. Figure 18.5e Gross anatomy of the heart. Aorta Left pulmonary artery Superior vena cava Right pulmonary artery Left atrium Left pulmonary veins Pulmonary trunk Right atrium Mitral (bicuspid) valve Right pulmonary veins Fossa ovalis Aortic valve Pectinate muscles Pulmonary valve Tricuspid valve Right ventricle Left ventricle Chordae tendineae Papillary muscle Interventricular septum Trabeculae carneae Epicardium Inferior vena cava Myocardium Endocardium Frontal section © 2013 Pearson Education, Inc. Atria: The Receiving Chambers • Small, thin-walled • Contribute little to propulsion of blood • Three veins empty into right atrium: – Superior vena cava, inferior vena cava, coronary sinus • Four pulmonary veins empty into left atrium © 2013 Pearson Education, Inc. Ventricles: The Discharging Chambers • Most of the volume of heart • Right ventricle - most of anterior surface • Left ventricle – posteroinferior surface • Trabeculae carneae – irregular ridges of muscle on walls • Papillary muscles – anchor chordae tendineae © 2013 Pearson Education, Inc. Ventricles: The Discharging Chambers • Thicker walls than atria • Actual pumps of heart • Right ventricle – Pumps blood into pulmonary trunk • Left ventricle – Pumps blood into aorta (largest artery in body) © 2013 Pearson Education, Inc. Figure 18.5b Gross anatomy of the heart. Left common carotid artery Brachiocephalic trunk Left subclavian artery Superior vena cava Aortic arch Ligamentum arteriosum Right pulmonary artery Left pulmonary artery Ascending aorta Left pulmonary veins Pulmonary trunk Auricle of left atrium Right pulmonary veins Circumflex artery Right atrium Right coronary artery Left coronary artery (in coronary sulcus) (in coronary sulcus) Anterior cardiac vein Left ventricle Right ventricle Right marginal artery Great cardiac vein Anterior interventricular Small cardiac vein artery (in anterior Inferior vena cava interventricular sulcus) Apex Anterior view © 2013 Pearson Education, Inc. Figure 18.5a Gross anatomy of the heart. Aortic arch (fat covered) Pulmonary trunk Auricle of right atrium Auricle of left atrium Anterior interventricular artery Right ventricle Apex of heart (left ventricle) Anterior aspect (pericardium removed) © 2013 Pearson Education, Inc. Figure 18.5f Gross anatomy of the heart. Superior vena cava Ascending aorta (cut open) Pulmonary trunk Aortic valve Right ventricle anterior wall (retracted) Pulmonary valve Trabeculae carneae Interventricular septum (cut) Opening to right atrium Left ventricle Chordae tendineae Papillary muscles Right ventricle Photograph; view similar to (e) © 2013 Pearson Education, Inc. Heart Valves • Ensure unidirectional blood flow through heart • Open and close in response to pressure changes • Two atrioventricular (AV) valves – Prevent backflow into atria when ventricles contract – Tricuspid valve (right AV valve) – Mitral valve (left AV valve, bicuspid valve) – Chordae tendineae anchor cusps to papillary muscles • Hold valve flaps in closed position © 2013 Pearson Education, Inc. Figure 18.7 The atrioventricular (AV) valves. 1 Blood returning to the heart fills atria, pressing against the AV valves. Direction of The increased pressure forces AV blood flow valves open. Atrium Cusp of 2 As ventricles fill, AV valve flaps atrioventricular hang limply into ventricles. valve (open) Chordae 3 Atria contract, forcing additional tendineae blood into ventricles. Papillary Ventricle muscle AV valves open; atrial pressure greater than ventricular pressure Atrium Cusps of 1 Ventricles contract, forcing atrioventricular blood against AV valve cusps. valve (closed) 2 AV valves close. Blood in ventricle 3 Papillary muscles contract and chordae tendineae tighten, preventing valve flaps from everting into atria. AV valves closed; atrial pressure less than ventricular pressure © 2013 Pearson Education, Inc. Heart Valves • Two semilunar (SL) valves – Prevent backflow into ventricles when ventricles relax – Open and close in response to pressure changes – Aortic semilunar valve – Pulmonary semilunar valve © 2013 Pearson Education, Inc. Figure 18.8 The semilunar (SL) valves. Aorta Pulmonary trunk As ventricles contract and intraventricular pressure rises, blood is pushed up against semilunar valves, forcing them open. Semilunar valves open As ventricles relax and intraventricular pressure falls, blood flows back from arteries, filling the cusps of semilunar valves and forcing them to close. Semilunar valves closed © 2013 Pearson Education, Inc. Figure 18.6a Heart valves. Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Myocardium Mitral (left atrioventricular) valve Tricuspid (right atrioventricular) valve Aortic valve Pulmonary valve Cardiac skeleton Anterior © 2013 Pearson Education, Inc. Figure 18.6b Heart valves. Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Myocardium Mitral (left atrioventricular) valve Tricuspid (right atrioventricular) valve Aortic valve Pulmonary valve © 2013 Pearson Education, Inc. Figure 18.6c Heart valves. Pulmonary valve Aortic valve Area of cutaway Mitral valve Tricuspid valve Chordae tendineae attached Papillary to tricuspid valve flap muscle © 2013 Pearson Education, Inc. Figure 18.6d Heart valves. Pulmonary valve Aortic valve