1. PRINCIPLES OF HUMAN PHYSIOLOGY THIRD EDITION Cindy L. Stanfield | William J. Germann PowerPoint ® Lecture Slides prepared by W.H. Preston, College of the Sequoias Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. 13 Part A The Cardiovascular System: Cardiac Function

2. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 13.1 Anatomy of the Heart Four Chambers Two atria Two ventricles Valves Atrioventricular Semilunar Interventricular septum Base Apex

3. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Path of Blood Flow Cardiovascular system = closed system Flow through systemic and pulmonary circuits is in series Left ventricle  aorta  systemic circuit  vena cavae  right atrium  right ventricle  pulmonary artery  pulmonary circuit  pulmonary veins  left atrium  left ventricle

4. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Path of Blood Flow Figure 13.2

5. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Heart Location Figure 13.5

6. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Ventricular Muscle Figure 13.6

7. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Properties of Cardiac Muscle Cells are smaller than cells of skeletal muscle Cells demonstrate branching Striations are evident

8. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Properties of Cardiac Muscle Intercalated disks Gap junctions Cause heart to contract as a unit Desmosomes Resist stress Atria and ventricles Separate units

9. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Properties of Cardiac Muscle Aerobic muscle No cell division after infancy—growth by hypertrophy 99% contractile cells (for pumping) 1% autorhythmic cells (set pace)

10. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Function of Cardiac Muscle Rhythmic contraction and relaxation generates heart pumping action Contraction pushes blood out of heart into vasculature Relaxation allows heart to fill with blood

11. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Heartbeat Wave of contraction through cardiac muscle Atria contract as a unit Ventricles contract as a unit Atrial contraction precedes ventricle contraction

12. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Valves and Unidirectional Blood Flow Pressure within chambers of heart vary with heartbeat cycle Pressure difference drives blood flow High pressure to low pressure Normal direction of flow Atria to ventricles Ventricles to arteries Valves prevent backward flow of blood All valves open passively based on pressure gradient

13. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Atrioventricular Valve Action Figure 13.7

14. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Semilunar Valve Action Figure 13.8

15. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Autorhythmic Cells LocationFiring Rate at Rest SA Node 70-80 APs/min* AV Node40-60 APs/min Bundle of His20-40 APs/min Purkinje Fibers20-40 APs/min Cardiac cells are linked by gap junctions Fastest depolarizing cells control other cells Fastest cells = pacemaker = set rate for rest of heart * action potentials per minute

16. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Cardiac Electrical Connections Figure 13.9

17. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Conduction System of Heart Figure 13.10

18. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Pathway of Depolarization Figure 13.11

19. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Electrical Activity: Pacemaker Cell Figure 13.12

20. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Electrical Activity: Pacemaker Cell Table 13.1

21. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Electrical Activity: Contractile Cell Figure 13.13

22. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings. Electrical Activity: Contractile Cell Table 13.2