Copyright 2010, John Wiley & Sons, Inc. Chapter 15 The Cardiovascular System: The Heart Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Heart Anatomy http://www.youtube.com/watch?v=H04d3rJCLCE Copyright 2010, John Wiley & Sons, Inc.

Chapter 15 Cardiovascular System Average Size of Heart 14 cm long 9 cm wide Copyright 2010, John Wiley & Sons, Inc. 15-2

Copyright 2010, John Wiley & Sons, Inc. Location of the Heart Posterior to sternum Anterior to vertebral column Thoracic cavity between two lungs ~2/3 to left of midline Base lies beneath 2nd rib Apex at 5th intercostal space Lies upon diaphragm Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Location of the Heart Surrounded by pericardium: Fibrous pericardium - Inelastic and anchors heart in place Serous pericardium - double layer around heart Parietal layer fused to fibrous pericardium Inner Visceral layer adheres tightly to heart Filled with Pericardial fluid - reduces friction during beat. Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Pericardium Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Position of the Heart Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Position of the Heart Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Heart Wall Epicardium - outer layer serous membrane protective covering contains capillaries and nerve fibers Myocardium - cardiac muscle Contracts to pump blood Two networks via gap junctions in intercalated discs - atrial & ventricular Networks - contract as a unit Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Heart Wall Endocardium - Squamous epithelium lines inside of myocardium forms protective inner lining membrane of epithelial and connective tissues Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Cardiac Muscle Fibers Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Cardiac Muscle Tissue Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Chambers of the Heart 4 chambers 2 upper chambers = Atria Between is interatrial septum Contains fossa ovalis 2 lower chambers = ventricles Between is interventricular septum Wall thickness depends on work load Atria thinnest Right ventricle pumps to lungs & thinner than left Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Heart Chambers Right Atrium receives blood from inferior vena cava superior vena cava coronary sinus Left Atrium receives blood from pulmonary veins Right Ventricle receives blood from right atrium Left Ventricle receives blood from left atrium Copyright 2010, John Wiley & Sons, Inc. 15-6

Copyright 2010, John Wiley & Sons, Inc. Structure of the Heart Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Skeleton of Heart fibrous rings to which the heart valves are attached Copyright 2010, John Wiley & Sons, Inc. 15-10

Copyright 2010, John Wiley & Sons, Inc. Valves Designed to prevent back flow in response to pressure changes Atrioventricular (AV) valves Between atria and ventricles Right = tricuspid valve (3 cusps) Left = bicuspid or mitral valve Semilunar valves near origin of aorta & pulmonary trunk Aortic & pulmonary valves respectively Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Heart Valves Copyright 2010, John Wiley & Sons, Inc. 15-9

Atrioventricular Valves: Bicuspid Valves Copyright 2010, John Wiley & Sons, Inc.

Atrioventricular Valves: Superior View Copyright 2010, John Wiley & Sons, Inc.

Great Vessels Of Heart-Right Superior & inferior Vena Cavae Delivers deoxygenated blood to R. atrium from body Coronary sinus drains heart muscle veins R. Atrium  R. Ventricle pumps through Pulmonary Trunk  R & L pulmonary arteries  lungs Copyright 2010, John Wiley & Sons, Inc.

Great Vessels Of Heart-Left Pulmonary Veins from lungs oxygenated blood  L. atrium  Left ventricle  ascending aorta  body Between pulmonary trunk & aortic arch is ligamentum arteriosum fetal ductus arteriosum remnant Copyright 2010, John Wiley & Sons, Inc.

Posterior View of Heart Copyright 2010, John Wiley & Sons, Inc.

Anterior View of Frontal Section Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Blood Supply Of Heart Blood flow through vessels in myocardium = coronary circulation Left & right coronary arteries branch from aorta to carry blood throughout muscle Deoxygenated blood collected by coronary sinus (posterior) Empties into right atrium Copyright 2010, John Wiley & Sons, Inc.

Blood Flow Through Heart Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Blood Flow Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Cardiac Cycle Atrial Systole/Ventricular Diastole blood flows passively into ventricles remaining 30% of blood pushed into ventricles A-V valves open/semilunar valves close ventricles relaxed ventricular pressure increases Atrial Diastole/Ventricular Systole blood flows into pulmonary trunk and aorta chordae tendinae prevent cusps of valves from bulging too far into atria & ventricles Copyright 2010, John Wiley & Sons, Inc. 15-17

Copyright 2010, John Wiley & Sons, Inc. Heart Actions Copyright 2010, John Wiley & Sons, Inc. 15-16

Copyright 2010, John Wiley & Sons, Inc. Heart Sounds Lubb first heart sound occurs during ventricular contraction A-V valves closing Dupp second heart sound occurs during atrial contraction semilunar valves closing Murmur – abnormal heart sound Copyright 2010, John Wiley & Sons, Inc. 15-18

Copyright 2010, John Wiley & Sons, Inc. Conduction System 1% of cardiac muscle generate action potentials = Pacemaker & Conduction system Normally begins at sinoatrial (SA) node Atria & atria contract AV node - slows AV bundle (Bundle of His) bundle branches  Purkinje fibers  apex and up - then ventricles contract Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Pacemaker Depolarize spontaneously sinoatrial node ~ 100 times /min AV node ~ 40-60 times/min Ventricle ~ 20-35 times/min Fastest one runs the heart = pacemaker Normally the sinoatrial node Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Frontal plane SINOATRIAL (SA) NODE ATRIOVENTRICULAR (AV) NODE Left atrium Left ventricle Anterior view of frontal section ATRIOVENTRICULAR (AV) BUNDLE (BUNDLE OF HIS) RIGHT AND LEFT BUNDLE BRANCHES PURKINJE FIBERS 1 2 3 4 5 Right atrium Right ventricle Frontal plane Left atrium Left ventricle Anterior view of frontal section SINOATRIAL (SA) NODE ATRIOVENTRICULAR (AV) NODE ATRIOVENTRICULAR (AV) BUNDLE (BUNDLE OF HIS) RIGHT AND LEFT BUNDLE BRANCHES 1 2 3 4 Right atrium Right ventricle Frontal plane Left atrium Left ventricle Anterior view of frontal section SINOATRIAL (SA) NODE ATRIOVENTRICULAR (AV) NODE ATRIOVENTRICULAR (AV) BUNDLE (BUNDLE OF HIS) 1 2 3 Right atrium Right ventricle Frontal plane Left atrium Left ventricle Anterior view of frontal section SINOATRIAL (SA) NODE ATRIOVENTRICULAR (AV) NODE 1 2 Right atrium Right ventricle Frontal plane Right atrium Right ventricle Left atrium Left ventricle Anterior view of frontal section Frontal plane Left atrium Left ventricle Anterior view of frontal section SINOATRIAL (SA) NODE 1 Right atrium Right ventricle Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Electrocardiogram EKG or ECG P wave = atrial depolarization Contraction begins right after peak Repolarization is masked in QRS QRS complex = Ventricular depolarization Contraction of ventricle T-wave = ventricular repolarization Just after ventricles relax Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. ECG Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Cardiac Cycle after T-wave  ventricular diastole AV valves open  ventricular filling occurs After P-wave  atrial systole Finishes filling ventricle (`30%) After QRS  ventricular systole Pressure pushes AV valves closed Pushes semilunar valves open Ejection until ventricle relaxes enough for arterial pressure to close semilunar valves Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Electrocardiogram A prolonged QRS complex may result from damage to the A-V bundle fibers Copyright 2010, John Wiley & Sons, Inc. 15-26

Copyright 2010, John Wiley & Sons, Inc. Cardiac Muscle Fibers Cardiac muscle fibers form functional syncytia group of cells that function as a unit atrial syncytium ventricular syncytium Copyright 2010, John Wiley & Sons, Inc. 15-20

Copyright 2010, John Wiley & Sons, Inc. Cardiac Cycle Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Flow Terms Cardiac Output (CO) = liters/min pumped Heart Rate (HR) = beats/minute (bpm) Stroke volume (SV) = volume/beat CO = HR x SV Copyright 2010, John Wiley & Sons, Inc.

Controls - Stroke Volume (S.V.) Degree of stretch = Frank-Starling law Increase diastolic Volume increases strength of contraction  increased S.V. Increased venous return  increased S.V. Increased by sympathetic activity High back pressure in artery  decreased S.V. Slows semilunar valve opening Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Controls - Heart Rate Pacemaker adjusted by nerves Cardiovascular center in Medulla Parasympathetic - ACh decrease heart action Via vagus nerve Sympathetic - norepinephrine increase heart action Sensory input: Baroreceptors (aortic arch & carotid sinus) - B.P. Chemoreceptors - O2, CO2, pH Copyright 2010, John Wiley & Sons, Inc.

Regulation of Cardiac Cycle Copyright 2010, John Wiley & Sons, Inc. 15-29

Copyright 2010, John Wiley & Sons, Inc. Other Controls Hormones: Epinephrine & norepinephrine increase H.R. Thyroid hormones stimulate H.R. Ions Increased Na+ or K+ decrease H.R. & contraction force Increased Ca2+ increases H.R. & contraction force Copyright 2010, John Wiley & Sons, Inc.

Autonomic Nervous System Regulation of Heart Rate Alter the activities of the S-A and A-V nodes Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Exercise and the Heart Aerobic exercise (longer than 20 min) strengthens cardiovascular system Well trained athlete  doubles maximum C.O. Resting C.O. about the same but resting H.R. decreased Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Life-Span Changes Deposition of cholesterol in blood vessels Heart enlarges Cardiac muscle cells die Fibrous connective tissue of heart increases Adipose tissue of heart increases Blood pressure increases Resting heart rate decreases Copyright 2010, John Wiley & Sons, Inc. 15-70

Copyright 2010, John Wiley & Sons, Inc. Clinical Application Arrhythmias Ventricular fibrillation Rapid, uncoordinated depolarization of ventricles Tachycardia Rapid heartbeat Atrial flutter Rapid rate of atrial depolarization Copyright 2010, John Wiley & Sons, Inc. 15-71

Copyright 2010, John Wiley & Sons, Inc. Heart Healthy Living http://www.youtube.com/watch?v=DWL67xOeQ-E Copyright 2010, John Wiley & Sons, Inc.