The Heart Chapter 20

Human Anatomy, 3rd edition Introduction Cardiovascular system distributes blood Pump (heart) Distribution areas (capillaries) Heart has 4 compartments 2 receive blood (atria) 2 pump blood out (ventricles) Vessels Veins return blood to the heart Arteries take blood away from the heart Human Anatomy, 3rd edition Prentice Hall, © 2001

Superficial Anatomy of the Heart Atria = “entrance ways” Thin-walled Upper chambers Ventricles = “hollow spaces” Thick, muscular Apex points down & tips slightly to the left Base is superior Great vessels attach Human Anatomy, 3rd edition Prentice Hall, © 2001

The Coverings of the Heart Pericardium = “around the heart” Visceral pericardium = epicardium Parietal pericardium Pericardial space contains pericardial fluid Human Anatomy, 3rd edition Prentice Hall, © 2001

Internal Anatomy of the Heart Chambers of the heart Right & left atrium Separated by the interatrial septum Right & left ventricle Separated by the interventricular septum Human Anatomy, 3rd edition Prentice Hall, © 2001

Structure of the Heart Wall Epicardium = “upon the heart” Myocardium is the middle layer Cardiac muscle Papillary muscles Chordae tendinae attach AV valves to the papillary muscles Endocardium = “inside the heart” Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Great Vessels Superior & inferior vena cava Return blood from body to right atrium Coronary Sinus Returns blood from heart wall to right atrium Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Great Vessels Pulmonary veins Return blood (oxygenated) from lungs to left atrium Aorta Takes blood from left ventricle to body Pulmonary artery Takes blood (deoxygenated) from right ventricle to lungs Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Valves of the Heart Atrioventricular (AV) valves separate the atria from the ventricles Tricuspid valve – right Bicuspid valve (mitral) – left Semilunar valves separate the ventricles from the great vessels Pulmonary semilunar valve Aortic semilunar valve Heart sounds Human Anatomy, 3rd edition Prentice Hall, © 2001

Valves of the Heart (Ventricular Diastole) FG21_07A.JPG Title: Valves of the Heart Notes: (a)Valve position during ventricular diastole; AV valves open, semilunar valves closed. (b)Cardiac valves during ventricular systole; AV valves closed, semilunar valves open. Note how chordae tendineae and papillary muscles affect movement of AV valve. Keywords: heart, valves, ventricular systole, tricuspid, fibrous skeleton, mitral valve, aortic semilunar, pulmonary semilunar, chordae tendineae, ventricle, papillary muscles Human Anatomy, 3rd edition Prentice Hall, © 2001

Valves of the Heart (Ventricular Systole) FG21_07B.JPG Title: Valves of the Heart Notes: (c)Superior view of heart valves. (d)Proper placement of a stethoscope varies depending on which heart sounds and valves are of interest. Keywords: heart, valves, pulmonary valve, aortic valve, mitral, atrium, vena cava, aorta, pulmonary trunk, heart sounds, stethoscope, aortic semilunar, pulmonary semilunar, mitral, tricuspid Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Coronary Circulation Vessels that supply the myocardium itself Right coronary artery Left coronary artery Cardiac veins Human Anatomy, 3rd edition Prentice Hall, © 2001

Cast of Coronary Vessels FG21_09C.JPG Title: Coronary Circulation Notes: (a)Vessels supplying anterior surface of heart. (b)Coronary vessels supplying posterior surface of heart. (c)Cast of coronary vessels. (d)Coronary angiogram, left lateral projection. Keywords: coronary, circulation, anterior, artery, vein, circumflex branch, anterior interventricular branch, great cardiac vein, marginal branch, posterior interventricular branch, middle cardiac vein, right coronary artery, small cardiac vein, coronary sinus Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition The Cardiac Cycle Contraction pattern of the myocardium Determined by the conduction system Systole = contraction Diastole = relaxation Both atria contract Both ventricles contract Atria alternate with ventricles Human Anatomy, 3rd edition Prentice Hall, © 2001

Conduction System of the Heart The average heart rate is 72 beats/min. Depolarization stimulates contraction Human Anatomy, 3rd edition Prentice Hall, © 2001

Conducting System of the Heart Depolarization begins in the sinoatrial (SA) node Pacemaker FG21_12B.JPG Title: The Conducting System of the Heart Notes: (a)The stimulus for contraction is generated by pacemaker cells at the SA node.(b)Movement of the contractile stimulus: SA node, AV node, atrial contraction, AV bundle and bundle branches, Purkinjie fibers, ventricular myocardium, ventricular contraction. Keywords: heart, conducting system, sinoatrial node, SA, atrioventricular, AV, AV bundle, bundle branch, Purkinje fibers Human Anatomy, 3rd edition Prentice Hall, © 2001

Conduction System of the Heart Depolarization spreads through atria, atria contract FG21_12C.JPG Title: The Conducting System of the Heart Notes: (a)The stimulus for contraction is generated by pacemaker cells at the SA node.(b)Movement of the contractile stimulus: SA node, AV node, atrial contraction, AV bundle and bundle branches, Purkinjie fibers, ventricular myocardium, ventricular contraction. Keywords: heart, conducting system, sinoatrial node, SA, atrioventricular, AV, AV bundle, bundle branch, Purkinje fibers

Conducting System of the Heart Atrioventricular (AV node) depolarizes Depolarization travels down the AV bundle (bundle of His) FG21_12E.JPG Title: The Conducting System of the Heart Notes: (a)The stimulus for contraction is generated by pacemaker cells at the SA node.(b)Movement of the contractile stimulus: SA node, AV node, atrial contraction, AV bundle and bundle branches, Purkinjie fibers, ventricular myocardium, ventricular contraction. Keywords: heart, conducting system, sinoatrial node, SA, atrioventricular, AV, AV bundle, bundle branch, Purkinje fibers Human Anatomy, 3rd edition Prentice Hall, © 2001

Conducting System of the Heart Depolarization spreads up the ventricular walls via Purkinje fibers. Ventricles contract FG21_12F.JPG Title: The Conducting System of the Heart Notes: (a)The stimulus for contraction is generated by pacemaker cells at the SA node.(b)Movement of the contractile stimulus: SA node, AV node, atrial contraction, AV bundle and bundle branches, Purkinjie fibers, ventricular myocardium, ventricular contraction. Keywords: heart, conducting system, sinoatrial node, SA, atrioventricular, AV, AV bundle, bundle branch, Purkinje fibers Human Anatomy, 3rd edition Prentice Hall, © 2001

Disorders Abnormal heart rates Angina pectoris Myocardial infarction Bradycardia Tachycardia Fibrillation Angina pectoris Myocardial infarction