Heart Continued Copyright 2009 Pearson Education Inc publishing

Heart Continued Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Review Blood Flow Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Coronary Circulation § Blood in the heart chambers does not nourish the myocardium (heart muscle) § The heart has its own nourishing circulatory system consisting of § Coronary arteries—branch from the aorta to supply the heart muscle with oxygenated blood § Cardiac veins—drain the myocardium of blood § Coronary sinus—a large vein where all of the cardiac veins come together on the posterior of the heart, receives blood from cardiac veins Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Coronary Circulation Blood empties into the right atrium via the coronary sinus Blood from the heart enters the coronary arteries through a branch at the base of the aorta. Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Coronary Circulation § Angina pectoris: -Chest pain due to inadequate supply of oxygen to the muscle -Indication some degree of coronary vessels blockage § Myocardial infarction: - Medical term for heart attack -Heart cells die from lack of blood supply -Usually caused by blockage of one of the coronary arteries Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

The Heart: Conduction System § Intrinsic conduction system (nodal system) § Heart muscle cells contract, without nerve impulses, they use nodes § http: //www. dailymotion. com/video/xhp 35 u_argosymedical-animation-sectioned-heart_tech Heart beat sounds: “lub dub” Sounds are made by the closing of the valves Lub is the AV valves closing Dub is the SA valves closing Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

The Heart: Conduction System § Special tissue: § Sinoatrial node = SA node (“pacemaker”), in right atrium § Atrioventricular node = AV node, at junction of the right atrium near the interatrial septum § Atrioventricular bundle = AV bundle in the interventricular septum § Bundle branches in the interventricular septum § Purkinje fibers spread within the ventricle wall muscles Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

SA node (sino-atrial node) § acts as the heart’s “pacemaker” § cells whose primary function is electrical conduction, not contractility § the action potential produced by its depolarization spreads across the atria (remember that action potential is the movement of molecules across the membranes of cells to create electrical current) Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Heart Contractions § Impulse spreads to the AV node § Then the atria contract § impulse passes through the AV bundle, bundle branches, and Purkinje fibers § the ventricles contract Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Heart Contraction § http: //highered. mcgrawhill. com/sites/0072495855/student_view 0/chapter 22/anim ation__conducting_system_of_the_heart. html Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Heart Contractions Figure 11. 6 Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

The Heart: Cardiac Cycle The cardiac cycle refers to 1 complete heart beat Normally. 8 sec for 1 cardiac cycle Cardiac cycle includes: § Systole = contraction § Diastole = relaxation Relates to the ventricles, unless otherwise stated Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Heart Contractions Normal Heart Rate: 75 beats/min § Tachycardia—rapid heart rate over 100 beats per minute (tachy= fast) § Bradycardia—slow heart rate less than 60 beats per minutes (brady= slow) Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

Filling Heart Chambers: Cardiac Cycle Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings

The Heart: Cardiac Cycle § Cardiac cycle—events of one complete heart beat § Mid-to-late diastole—blood flows from atria into ventricles § Ventricular systole—blood pressure builds before ventricle contracts, pushing out blood § Early diastole—atria finish refilling, ventricular pressure is low http: //highered. mcgrawhill. com/sites/0072495855/student_view 0/chap ter 22/animation__the_cardiac_cycle__quiz_1_. html Copyright © 2009 Pearson Education, Inc. , publishing as Benjamin Cummings