Transcript heart
The Cardiovascular System Chapter 13 Human Anatomy, 3rd edition Prentice Hall, © 2001 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” = visceral pericardium – Dense fibrous connective tissue • Myocardium is the middle layer – Cardiac muscle • Endocardium = “inside the heart” – Simple squamous epithelium Human Anatomy, 3rd edition Prentice Hall, © 2001 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 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 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) Human Anatomy, 3rd edition Prentice Hall, © 2001 Valves of the Heart (Ventricular Systole) Human Anatomy, 3rd edition Prentice Hall, © 2001 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 Human Anatomy, 3rd edition Prentice Hall, © 2001 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 Human Anatomy, 3rd edition Prentice Hall, © 2001 Conduction System of the Heart •Depolarization spreads through atria, atria contract Conducting System of the Heart • Atrioventricular (AV node) depolarizes • Depolarization travels down the AV bundle (bundle of His) Human Anatomy, 3rd edition Prentice Hall, © 2001 Conducting System of the Heart • Depolarization spreads up the ventricular walls via Purkinje fibers. – Ventricles contract Human Anatomy, 3rd edition Prentice Hall, © 2001 Electrocardiogram – ECG = a recording of electrical events in the heart • P wave = atrial depolarization • QRS wave = ventricular depolarization • T wave = ventricular repolarization Human Anatomy, 3rd edition Prentice Hall, © 2001 Electrocardiogram Human Anatomy, 3rd edition Prentice Hall, © 2001 Electrocardiogram Human Anatomy, 3rd edition Prentice Hall, © 2001 Disorders • Abnormal heart rates – Bradycardia – Tachycardia – Fibrillation • Angina pectoris • Myocardial infarction Human Anatomy, 3rd edition Prentice Hall, © 2001 Blood Vessels Human Anatomy, 3rd edition Prentice Hall, © 2001 Functions of Blood Vessels • Carry blood away from the heart - arteries • Transport blood to tissues - capillaries • Return blood to the heart – veins Human Anatomy, 3rd edition Prentice Hall, © 2001 Walls of Blood Vessels • 3 layers – Inner layer is endothelium = tunica intima • Simple squamous epithelium – Middle layer = tunica media • Smooth muscle – Outer layer = tunica externa • Dense fibrous connective tissue Human Anatomy, 3rd edition Prentice Hall, © 2001 Atherosclerosis Human Anatomy, 3rd edition Prentice Hall, © 2001 Arteries • Elastic arteries large arteries • Muscular arteries - medium-sized arteries • Arterioles - very small – Capable of vasoconstriction and vasodilation Human Anatomy, 3rd edition Prentice Hall, © 2001 Systemic Arterial System Human Anatomy, 3rd edition Prentice Hall, © 2001 Major Arteries of the Trunk Human Anatomy, 3rd edition Prentice Hall, © 2001 Arteries of the Chest and Upper Extremity Human Anatomy, 3rd edition Prentice Hall, © 2001 Capillaries • All blood-tissue exchange occurs here • Tissue = tunica intima only • Three types – Continuous – Fenestrated – Sinusoids Human Anatomy, 3rd edition Prentice Hall, © 2001 Capillary Bed with Precapillary Sphincters Human Anatomy, 3rd edition Prentice Hall, © 2001 Veins • Venules – Very small – Contain only tunica intima and tunica externa • Medium-sized veins and large veins – Contain same 3 layers as arteries – Tunica media thinner – Tuna externa - thickest layer Human Anatomy, 3rd edition Prentice Hall, © 2001 Veins with Valves • Some veins contain valves – prevent blood from flowing backwards Human Anatomy, 3rd edition Prentice Hall, © 2001 Varicose Veins • www.sirweb.org/patPub/varicoseVeinMain.shtml Human Anatomy, 3rd edition Prentice Hall, © 2001 www.veinhelp.com/varicoseVeins.htm Systemic Venous System Human Anatomy, 3rd edition Prentice Hall, © 2001 Venous System of the Trunk and Upper Limb Human Anatomy, 3rd edition Prentice Hall, © 2001 Blood Flow – Blood flows because of different pressures in the system • Mean pressure in aorta = 100 mmHg – Pressure decreases continuously through arterial and venous system • • • • • • Arteries = 100 – 40 mmHg Arterioles = 40 – 25 mmHg Capillaries = 25 – 12 mmHg Venules = 12 – 8 mmHg Veins = 8 – 5 mmHg Vena cava = 2 mmHg Human Anatomy, 3rd edition Prentice Hall, © 2001 Blood Pressure – Definition – force exerted by blood on the wall of any blood vessel – Clinical use – refers to pressure in the arteries • Ventricles contract (systole) – Arterial pressure rises – Systolic pressure • Ventricles relax (diastole) – Arterial pressure drops – Diastolic pressure • Average blood pressure – 120/80 (young male) – 110/70 (young female) – Hypertension Human Anatomy, 3rd edition Prentice Hall, © 2001