Heart Continued

1. Heart Continued

2. Review Blood Flow

3. 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

4. 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.

5. 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

6. The Heart: Conduction System • Intrinsic conduction system (nodal system) • Heart muscle cells contract, without nerve impulses, they use nodes • http://www.dailymotion.com/video/xhp35u_argosy-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

7. 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

8. 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)

9. 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

10. Heart Contraction • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter22/animation__conducting_system_of_the_heart.html

11. Heart Contractions Figure 11.6

12. 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

13. 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)

14. Filling Heart Chambers: Cardiac Cycle

15. 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.mcgraw-hill.com/sites/0072495855/student_view0/chapter22/animation__the_cardiac_cycle__quiz_1_.html