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. Location of the Heart Thoracic cavity between two lungs ~2/3 to left of midline surrounded by pericardium: Fibrous pericardium - Inelastic and anchors heart in place Inside is 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. 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 Myocardium - cardiac muscle Two separate networks via gap junctions in intercalated discs - atrial & ventricular Networks- contract as a unit Endocardium - Squamous epithelium lines inside of myocardium 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. 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 - remnant of foramen 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. Structure of the Heart Copyright 2010, John Wiley & Sons, Inc.

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

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

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

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

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 ~100times /min also AV node ~40-60 times/min in ventricle ~20-35 /min Fastest one run runs the heart = pacemaker Normally the sinoatrial node Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. 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 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) 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 Recording of currents from cardiac conduction on skin = 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 Ventricular pressure drops below atrial & AV valves open  ventricular filling occurs After P-wave atrial systole Finishes filling ventricle (`25%) After QRS ventricular systole Pressure pushes AV valves closed Pushes semilunar valves open and ejection occurs Ejection until ventricle relaxes enough for arterial pressure to close semilunar valves Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Action Potential Review muscle Heart has addition of External Ca2+ Creates a plateau Prolonged depolarized period Can not go into tetanus Copyright 2010, John Wiley & Sons, Inc.

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 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 slows Via vagus nerve Sympathetic - norepinephrine speeds Sensory input for control: baroreceptors (aortic arch & carotid sinus)- B.P. Chemoreceptors- O2, CO2, pH Copyright 2010, John Wiley & Sons, Inc.

Copyright 2010, John Wiley & Sons, Inc. Other Controls Hormones: Epinephrine & norepinephrine increase H.R. Thyroid hormones stimulate H.R. Called tachycardia 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 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. End of Chapter 15 Copyright 2010 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publishers assumes no responsibility for errors, omissions, or damages caused by the use of theses programs or from the use of the information herein. Copyright 2010, John Wiley & Sons, Inc.