Chapter 18- The Cardiac Cycle,Coronary Circulation, and ECG
Chapter 18- The Cardiac Cycle,Coronary Circulation, and ECG KNR 182
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This 52 page Bundle was uploaded by Christina on Wednesday October 21, 2015. The Bundle belongs to KNR 182 at Illinois State University taught by Dr. Rinaldi-MIles in Summer 2015. Since its upload, it has received 51 views. For similar materials see Human Anatomy and Physiology II (lecture) in Kinesiology at Illinois State University.
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HUMAN ANATOMY amp PHYSIOLOGY KNR 182 Cardiovascular System Chapter 18 Cardiac Cycle Coronary Circulation amp ECG Cardiac Cycle Mechanical activityevents of the pump Two events occur Systole also referred to as contraction depolarization or ejection CONTRACTION Diastole also referred to as relaxation repolarization or filling RELAXATION Therefore we have Atrial systole Atrial diastole Ventricular systole Ventricular diastole pressure dictates flow Pressure changes cause blood to move What influences pressure changes Mechanical events systole and Diastole Phases of the Cardiac Cycle 1 Ventricular filling takes place in midtolate diastole AV valves are open 80 of blood passively flows into ventricles Atrial systole occurs delivering the remaining 20 Atria are going to contract to squeeze the remaining 20 to the ventircles End diastolic volume EDV volume of blood in each ventricle at the end of ventricular diastole Phases of the Cardiac Cycle 2 Ventricular systole Atria relax and ventricles begin to contract Rising ventricular pressure results in closing of AV valves lsovoumetric contraction phase all valves are closed lso equal In ejection phase ventricular pressure exceeds pressure in the large arteries forcing the SL valves open So blood can flow out of ventricles End systolic volume ESV volume of blood remaining in each ventricle Phases of the Cardiac Cycle 3 lsovolumetrio relaxation occurs in early diastole Ventrioles relax Backflow of blood in aorta and pulmonary trunk closes SL valves VIDEO YouTube The Caridac Cvcle Left heart Electrocardiogram Heart sounds Important 12 figure 80 Left ventricle 40 Pressure mm Hg Atrial systole 39 39 E L39 397 120 Ventricular volume ml 50 ESV Atrioventricular valves Open l Aortic and pulmonary valves Closed Closed I Phasel Left atrium Right atrium Left ventricle Right ventricle Ventricular Atrial sovoumetric Ventricular lsovolumetric Ventricular filling contraction contraction phase ejection phase relaxation filling lt13 I e go Ventricular filling Ventricular systole Early diastole midtolate diastole atria in diastole Figure 1820 Important Figure Atrioventricularvalves Open Open Aortic and pulmonary valves I cm open nosed Phase 1 123 25 1 3 I 1 39 39 39 Left atrium Right atrium Left ventricle L i N Right ventricle J Ventricula Atrial isovol memo Ventricula lsovolurnetrio Ventricula filling contraction contraction phase ejection phase relaxation lling I G l a 6 I I I Ventricula filling Ventricula systole Early diastole midtoIate diastole atria in diastole One influences the other All of the parts work together Coronary Circulation The functional blood supply to the heart muscle itself Arterial supply varies considerably and contains many anastomoses junctions among branches Collateral routes provide additional routes for blood delivery Coronary circuit shortest route Your heart needs 120th of your total oxygen supply Coronary Circulation Arteries Right and left coronary in atrioventricular groove marginal circumflex and anterior interventricular arteries Veins Small cardiac anterior cardiac and great cardiac veins Veins drain into coronary sinus Left common carotid artery Left subclavran artery Aortic arch Ligamentum arteriosum Brachiocephalic trunk Superior vena cava Right pulmonary artery Ascending aorta Pulmonary trunk Right pulmonary lt39 Left pulmonary artery Left pulmonary veins Auricle of left atrium Circumflex artery Left coronary artery veins Right atrium Right coronary artery in coronary sulcus Anterior cardiac vein in coronary sulcus i Left ventricle Great cardiac vein Anterior interventricular g artery in anterior v 39 interventricularsulcus Right ventricle Right marginal artery Small cardiac vein Inferior vena cava b Anterior View Apex Figure 184b The left and right coronary arteries supply blood to the tissues of the heart Copyright The McGrawHill Companies Inc Permission required for reproduction or display Aorta V Right coronary artery V V V Posterior interventricular Marginal Circumflex artery artery artery Myocardial Myocardial Myocardial capillaries in capillaries in capillaries in ventricular walls of right walls of left walls atrium and right atrium and left ventricle ventricle V V V Cardiac veins V Coronary sinus V Right atrium V Left coronary artery V Anterior interventricular artery V Myocardial capillaries in ventricular walls V Copyright The McGrawHill Companies Inc Permission required for reproduction or display Aorta Part of aona removed Aortic valve cusps Right coronary opening of artery left coronary artery Aorta Pulmonary trunk Supenor L A39 J vena cava quot39 I 1 Left atrium Anastomosis junction of vessels Left coronary Right artery atrium Circumflex Right artery coronary artery Left Right ventrlcle ventricle Anterior Right interventricular mammal Posterior artery artery interventricular artery a The major coronary arteries Figure 187a Supe or vena cava Anterior Great cardiac card39ac veins Vem Coronary sinus Small cardiac vein Middle cardiac vein b The major cardiac veins Figure 187b Homeostatic Imbalances Angina pectoris Thoracic pain caused by a fleeting deficiency in blood delivery to the myocardium Causes chest pain Does not cause death of cells but weakens the cells Cells are weakened Myocardial infarction heart attack Prolonged coronary blockage cardiac muscle cells die Areas of cell death are repaired with noncontractile scar tissue Not autoarithmic makes it hard for heart to pump efficiently YouTube Animation How a Heart attack Happens Homeostatic lmbalances Cardiomyopathy Degeneration of the myocardium often with enlargement of the heart Heart becomes diseased and myocardium becomes enlarged One side becomes larger than the other typically the left side Causes it to become very ineffective at pumping blood Can lead to congestive heart failure YouTube 3D Medical Animation Congestive heart failure Control of the Heart Control of the Heart Pump Since the atria are responsible for pumping blood to the ventricles we want Atrial systole to occur during ventricular diastole Ventricular systole to occur during atrial diastole Therefore we must coordinate the activity between the atria and the ventricles HOW Heart Physiology Electrical Events Electricity Electrical activity associated with the heart controls systole and diastole Intrinsic and Extrinsic innervations of the heart lntrinsic within our heart we have the ability to get these electrical events started does not rely on the nervous system Extrinsic CNS allows heart to pick up signals from the brain that tells the heart to beat faster slower based on what is going on outside of the body Intrinsic nnenation of the Heart Intrinsic cardiac conduction system A network of noncontractile autorhythmic cells that initiate and distribute impulses to coordinate the depolarization and contraction of the heart Electrical Events Action potential A rapid sequence of electrical changes including depolarization followed by repolarization once initiated it is selfgenerating Depolarization A change in membrane potential such that the cell interior becomes relatively less negative more positive this change is transmitted from cell to cell creating a wave or impulse of electrical activity Initiates contraction of the heart Electrical Events KEY POINTS Depolarization immediately precedes contraction Repolarization immediately precedes relaxation YouTube Cardiac conduction system and understanding ECG animation Cardiac Conduction System Copyright The McGrawHill Companies Inc Permission required for reproduction or display Nodes are clumps or strands of specialized cardiac muscle tissue which initiate and distribute impulses throughout the myocardium Forms a network that acts as a functional unit called a syncytium Atrial syncytium contracts as a unit SA node Atrial syncytium Junctional fibers AV node AV bundle Bundle branches Purkinje fibers Ventricular syncytium Heart Physiology Sequence of Excitation 1 Sinoatrial SA node pacemaker Spontaneous depolarization Generates impulses about 75 timesminute sinus rhythm Avg resting heart rate 60100 beats a minute Depolarizes faster than any other part of the myocardium Intrinsic control also has extrinsic control autonomic nervous system If situational environmental controls demand the heart to beat slower or faster lntranodal and intraatrial fibers Atrial myocardial contraction Need to be able to identify structures for exam Heart Physiology Sequence of Excitation 2 Atrioventricular AV node Delays impulses approximately 01 second spontaneously Depolarizes 50 times per minute in absence of SA node input Drastically decreases a resting heart rate Intrinsic control also has extrinsic control autonomic nervous system Heart Physiology Sequence of Excitation 3 Atricventricular AV bundle bundle of His Only electrical connection between the atria and ventricles Heart Physiology Sequence of Excitation 4 Right and left bundle branches Two pathways in the interventrioular septum that carry the impulses toward the apex of the heart Allows impulse to go to both ventricles and down to the apex Heart Physiology Sequence of Excitation 5 Purkinje fibers Complete the pathway into the apex and ventricular walls AV bundle and Purkinje fibers depolarize only 30 times per minute in absence of AV node input Ventricular myocardial contraction Bottom of the heart contracts first then moves up causes blood to move up and out of the heart The sinoatrial SA node pacemaker generates impulses lnternodal pathway The impulses pause 01 s at the atrioventricular AV node The atrioventricular AV bundle connects the atria to the ventricles GD The bundle branches conduct the impulses through the interventricular septum C5 The Purkinje fibers depolarize the contractile cells of both ventricles Superior vena cava Right atrium Left atrium Purkinje fibers lnter ventricular septum a Anatomy of the intrinsic conduction system showing the sequence of electrical excitation Figure 1814a Sinoatrial node Atrloventricular node Lef l posterior bundle Right bundle Ba39cnmann39s bundlle His bundle Purkinje fibl39es action potential is described as a rapid sequence of electrical sequence depolarization is described as a change in membrane potential Depolarization contraction and systole SA node lnternodal pathways AV node AV bundle Purkinje fibers Figure 73 Transmission of the cardiac impulse through the heart showing the time of appearance in fractions of a second of the impulse in different parts of the heart Extrinsic Innervation of the Heart Heartbeat is modified by the ANS Cardiac centers are located in the medulla oblongata Cardioacceleratorv center innervates SA and AV nodes heart muscle and coronary arteries through sympathetic neurons Cardioinhibitorv center inhibits SA and AV nodes through parasympathetic fibers in the vagus nerves Extrinsic Innervation of the Heart Earasympathetic Eause impulses decrease heart action ympathetic peed up impulses increase heart action influences how forceful the contractions are how fast the heart beats how much blood is pumped out of the blood Additional factors that may influence heart rate include Physical exercise Body temperature when body temp increases heartbeat increases Concentration of various ions including Potassium can make resting membrane potential more negative Calcium can make resting membrane potential more positive C tl l NEI VHHS SFSIZEH I I ElW Brain and Spinal C lumn NEFVIZHIS System Central and PEFiliill r l NEFVIZHIS System 51311501 Di ir i i f h Im r Di ir i i r39 t divisi n Eff r t di FiSi WWIE iii ENE ENS iii mu sg glands re t Aut n mic Nerv u S l Haw1mm rstem ANS rstem ENS EMS in 3mmth mu ENS 112m mu s WWIMi mus e and glands j e f 1 Sympathetic divisi n 13f ANS P r fl lllii l di ir i i ll 13f ANS En rrj Expenditure Energy C SElW39 Dorsal motor nucleus of vagus Cardioinhibitory center 2 M l S mpathetic trunk ganglion edulla oblongata Cardio acceleratory center Thoracic spinal cord Sympathetic trunk AV node SA node I Parasympathetic fibers I Sympathetic fibers I lnterneurons Figure 1815 Electrocardiography Electrocardiogram ECG or EKG a composite of all the action potentials generated by nodal and contractile cells at a given time Able to modify and amplify the electrical activity and record it to determine the health of the electrical conduction system of the heart Depolarization precedes contractions systole Repolarization precedes relaxation diastole Three waves 1 P wave depolarization of SA node 2 QRS complex ventricular depolarization 3 T wave ventricular repolarization Sinoatrial node Atrial depolarization l Atrioventricular node QRS complex Ventricular depolarization Ventricular repolarization l T Figure 1816 SA node I Depolarization I Repolarization D Atrial depolarization initiated by the SA node causes the P wave depolarization precedes contraction Figure 1817 step 1 I Depolarization SA node B I Repolarization D Atrial depolarization initiated by the SA node causes the P wave With atrial depolarization complete the impulse is delayed110 see so the K H atriararrbefr edrarthe vtnode Figure 1817 step 2 SA node I Depolarization I Repolarization D Atrial depolarization initiated by the SA node causes the P wave With atrial depolarization complete the impulse is delayed at the AV node R i it P Ii T lard h 03 Ventricular depolarization begins at apex causing the QRS complex Atrial repolarization occurs Figure 1817 step 3 I Depolarization R I Repolarization Q quotL 4 Ventricular depolarization is complete Figure 1817 step 4 I Depolarization I Repolarization atlas C4 Ventricular depolarization is complete R I I Qs Ventricular repolarization begins at apex causing the T wave ccurs at the same time as ventricular repolarization QRS complex Figure 1817 step 5 I Depolarization I Repolarization I S I I 4 Ventricular depolarization is complete Ventricular repolarization begins at apex causing the T wave Ventricular repolarization is complete Figure 1817 step 6 R I Depolarization I Repolarization R p T f x T Q P S m Atrial depolarization initiated by the SA node causes the Q S l P Wave Ventricular depolarization AV node B IS complete R p T Q S jr s exh With atrial depolarization Q complete the impulse is 5 Ventricular repolarization delayed at the AV node begins at apex causing the R T wave R p l T Q S o Ventricular depolarization S begins at apex causing the x a lt6 Ventricular repolarization QRS complex Atrial IS complete repolarization occurs Figure 1817 Sinoatrial node Atrioventricular node Time s 0 02 04 06 08 07 Interval Copynml 02001 Beniamin Cummings an Imprint a mason Wesley Longnan Inc Electrical Conducting System and Mechanical Activity Anatomical Electrical Mechanical Structure Activity Event C SA node pacemaker intrinsic control Intranodal and intraatrial bers K PWave K AV node Bundle of His 3 Right amp Left Bundle Branches lt5 Purkinje Fibers gt Atrial Systole during Ventricular Diastole QRS Complex Ventricular Systole during Atrial Diastole gt Atrial Diastole and Ventricular Diastole Twave Electrical Activity Always Precedes Mechanical Activity Phases of the Carliar Cycle Electrical Time Phase Activity Mechanical Activity Valve Posl nn Blood Flaw 03 see EKG wave Direction farm 1 PrWave Atria eontraelra during From the ventricular relaxatien AV Valve Opemecl atria 01 see Le ventricular lling Semllimar Valve Closed into the 125 aciiire iir39ag ventricles SA node generates impulse Impulse delayed atrial excitation begins at AV node Copyright 2001 Beniamin Cummings an imprint ol Addison Wesley Longn Lelt atrium Right atrium Lelt ventricle Right ventricle J Ventricular lling Atrial contraction I Ventricular fillan b midlolate diastole Phases ef39tllle Cardiac Cycle Electrical Time Phase Activity Mechanical Activity Valve Position Elem Flow 08 sec EKG wave D39ireetien form 1 PWave Atria eentraeta luring From the ventricular relaxatien AV Valve Opened atria 11 see Le ventricular filling Semllunar Valve Clos ed late the 125 ac ve lling ventricles 2 QRSWave Ventrlelee contract luring From the er atrial relaxatien AV Valve Cleeedl ventricles 03 see QRSCemplex Le ventricular ejection Semllunar Valve Opera into the 375 isavelumetrfc summertime arteries rapid ejecrfen reduced ejectfen Impulse passes to Ventricular excitation heart apex ventricular complete excitation begins Isovolumetnc Ventricular contraction phase ejection phase I Ventricular systole atria in diastole As ventricles contract and intraventricular 1 3 pressure rises blood 39 39 is pushed up against A ona ltj semilunar valves forcing them open Pulmonary 39 I artery As ventricles relax and intraventricular pressure falls blood flows back from arteries filling the cusps of semilunar valves and forcing them to close quot39 le 39 I JUN Pressure dictates blood fl ow l N Semilunar valve closed b Copyright 2001 Benjamin Cummings an imprint ol Adason Wesley Longnan Inc Phases ef39tllle Cardiac Cycle Electrical Time Phase Activity Mechanical Activity Valve Position Elem Flow 08 sec EKG wave D39ireetien form 1 PWave Atria eentraeta luring From the ventricular relaxatien AV Valve Opened atria 11 see Le ventricular filling Semllunar Valve Clos ed late the 125 ac ve lling ventricles 2 QRSWave Ventrlelee contract luring From the er atrial relaxatien AV Valve Cleeedl ventricles 03 see QRSCemplex Le ventricular ejection Semllunar Valve Opera into the 375 isavelumetrfc summertime arteries rapid ejecrfen reduced ejectfen Impulse passes to Ventricular excitation heart apex ventricular complete excitation begins Isovolumetnc Ventricular contraction phase ejection phase I Ventricular systole atria in diastole Phases nf39tlme Cardiac Cycle Electrical Time Phase Activity Mechanical Activity Valve Pnsi nln Blend Flaw 03 see EKG wave Direction farm 1 P39l Impulse passes t9 Ventricular excitation ha Efilal x gei m39a39 quot quot AV I 01 see p 39n 39 39 1e 125 E I39 leg 39 s 2 QRE quot u a l he Ill lee 03 see I 39 lsovolumetric Ventricular QRSJ S39 a39g i39 es relaxation filling m 375 es I I M Early diastole 3 Twave Atrial relaxatinn and From the ventricular relaxatien AV Valve Open veins into the IL fl see ie ventricular filling Semilnnar Valve Cline ed atria into the 501 fenvelnmetrfe relaxarfan ventricles peaefve llfng LubDub sound in the heart due to mechanical pressure At the end of ventricular systole we hear the LUB atrioventricular valves slamming shut DUB semilunar valves are slamming shut
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