Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings 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  medical-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  hill.com/sites/ /student_view0/chapter22/anim ation__conducting_system_of_the_heart.html hill.com/sites/ /student_view0/chapter22/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 hill.com/sites/ /student_view0/chap ter22/animation__the_cardiac_cycle__quiz_1_. html