1. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings C h a p t e r 20 The Heart PowerPoint® Lecture Slides prepared by Jason LaPres Lone Star College - North Harris Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

2. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Introduction to Cardiovascular System  The Pulmonary Circuit  Carries blood to and from gas exchange surfaces of lungs  The Systemic Circuit  Carries blood to and from the body  Blood alternates between pulmonary circuit and systemic circuit

3. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Introduction to Cardiovascular System  Three Types of Blood Vessels  Arteries  Carry blood away from heart  Veins  Carry blood to heart  Capillaries  Networks between arteries and veins

4. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Introduction to Cardiovascular System  Capillaries  Also called exchange vessels  Exchange materials between blood and tissues  Materials include dissolved gases, nutrients, wastes

5. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Introduction to Cardiovascular System Figure 20–1 An Overview of the Cardiovascular System.

6. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Introduction to Cardiovascular System  Four Chambers of the Heart  Right atrium  Collects blood from systemic circuit  Right ventricle  Pumps blood to pulmonary circuit  Left atrium  Collects blood from pulmonary circuit  Left ventricle  Pumps blood to systemic circuit

7. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Figure 20–2c Anatomy of the Heart  Great veins and arteries at the base  Pointed tip is apex  Surrounded by pericardial sac  Sits between two pleural cavities in the mediastinum

8. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–2a The Location of the Heart in the Thoracic Cavity

9. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Figure 20–2c Anatomy of the Heart  The Pericardium  Double lining of the pericardial cavity  Parietal pericardium  Outer layer  Forms inner layer of pericardial sac  Visceral pericardium  Inner layer of pericardium

10. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Pericardium  Pericardial cavity  Is between parietal and visceral layers  Contains pericardial fluid  Pericardial sac  Fibrous tissue  Surrounds and stabilizes heart

11. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–2b The Location of the Heart in the Thoracic Cavity

12. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–c2 The Location of the Heart in the Thoracic Cavity

13. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  Superficial Anatomy of the Heart  Atria  Thin-walled  Expandable outer auricle (atrial appendage)  Sulci  Coronary sulcus: divides atria and ventricles  Anterior interventricular sulcus and posterior interventricular sulcus: –separate left and right ventricles –contain blood vessels of cardiac muscle

14. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–3a The Superficial Anatomy of the Heart

15. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–3a The Superficial Anatomy of the Heart

16. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–3b The Superficial Anatomy of the Heart

17. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–3c The Superficial Anatomy of the Heart

18. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Heart Wall  Epicardium (outer layer)  Visceral pericardium  Covers the heart  Myocardium (middle layer)  Muscular wall of the heart  Concentric layers of cardiac muscle tissue  Atrial myocardium wraps around great vessels  Two divisions of ventricular myocardium  Endocardium (inner layer)  Simple squamous epithelium

19. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–4 The Heart Wall

20. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  Cardiac Muscle Tissue  Intercalated discs  Interconnect cardiac muscle cells  Secured by desmosomes  Linked by gap junctions  Convey force of contraction  Propagate action potentials

21. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–5 Cardiac Muscle Cells

22. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–5 Cardiac Muscle Cells

23. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–5 Cardiac Muscle Cells

24. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  Characteristics of Cardiac Muscle Cells  Small size  Single, central nucleus  Branching interconnections between cells  Intercalated discs

25. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart

26. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart

27. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  Internal Anatomy and Organization  Interatrial septum: separates atria  Interventricular septum: separates ventricles  Atrioventricular (AV) valves  Connect right atrium to right ventricle and left atrium to left ventricle  The fibrous flaps that form bicuspid (2) and tricuspid (3) valves  Permit blood flow in one direction: atria to ventricles The Heart: Valves

28. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Right Atrium  Superior vena cava  Receives blood from head, neck, upper limbs, and chest  Inferior vena cava  Receives blood from trunk, viscera, and lower limbs  Coronary sinus  Cardiac veins return blood to coronary sinus  Coronary sinus opens into right atrium

29. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Right Atrium  Foramen ovale  Before birth, is an opening through interatrial septum  Connects the two atria  Seals off at birth, forming fossa ovalis

30. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Right Atrium  Pectinate muscles  Contain prominent muscular ridges  On anterior atrial wall and inner surfaces of right auricle

31. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–6a-b The Sectional Anatomy of the Heart.

32. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–6a-b The Sectional Anatomy of the Heart.

33. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Right Ventricle  Free edges attach to chordae tendineae from papillary muscles of ventricle  Prevent valve from opening backward  Right atrioventricular (AV) Valve  Also called tricuspid valve  Opening from right atrium to right ventricle  Has three cusps  Prevents backflow

34. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Right Ventricle  Trabeculae carneae  Muscular ridges on internal surface of right (and left) ventricle  Includes moderator band: –ridge contains part of conducting system –coordinates contractions of cardiac muscle cells

35. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Pulmonary Circuit  Conus arteriosus (superior end of right ventricle) leads to pulmonary trunk  Pulmonary trunk divides into left and right pulmonary arteries  Blood flows from right ventricle to pulmonary trunk through pulmonary valve  Pulmonary valve has three semilunar cusps

36. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Left Atrium  Blood gathers into left and right pulmonary veins  Pulmonary veins deliver to left atrium  Blood from left atrium passes to left ventricle through left atrioventricular (AV) valve  A two-cusped bicuspid valve or mitral valve

37. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Left Ventricle  Holds same volume as right ventricle  Is larger; muscle is thicker and more powerful  Similar internally to right ventricle but does not have moderator band  Systemic circulation  Blood leaves left ventricle through aortic valve into ascending aorta  Ascending aorta turns (aortic arch) and becomes descending aorta

38. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–6c The Sectional Anatomy of the Heart.

39. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  Structural Differences between the Left and Right Ventricles  Right ventricle wall is thinner, develops less pressure than left ventricle  Right ventricle is pouch-shaped, left ventricle is round

40. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–7 Structural Differences between the Left and Right Ventricles

41. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–7 Structural Differences between the Left and Right Ventricles

42. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Heart Valves  Two pairs of one-way valves prevent backflow during contraction  Atrioventricular (AV) valves  Between atria and ventricles  Blood pressure closes valve cusps during ventricular contraction  Papillary muscles tense chordae tendineae: prevent valves from swinging into atria Figure 20–8

43. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Heart Valves  Semilunar valves  Pulmonary and aortic tricuspid valves  Prevent backflow from pulmonary trunk and aorta into ventricles  Have no muscular support  Three cusps support like tripod Figure 20–8

44. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  Aortic Sinuses  At base of ascending aorta  Sacs that prevent valve cusps from sticking to aorta  Origin of right and left coronary arteries

45. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–8a Valves of the Heart

46. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–8b Valves of the Heart

47. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–8c Valves of the Heart

48. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  Connective Tissues and the Cardiac (Fibrous) Skeleton  Physically support cardiac muscle fibers  Distribute forces of contraction  Add strength and prevent overexpansion of heart  Elastic fibers return heart to original shape after contraction

49. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Cardiac (Fibrous) Skeleton  Four bands around heart valves and bases of pulmonary trunk and aorta  Stabilize valves  Electrically insulate ventricular cells from atrial cells

50. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Blood Supply to the Heart = Coronary Circulation  Coronary arteries and cardiac veins  Supplies blood to muscle tissue of heart

51. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Coronary Arteries  Left and right  Originate at aortic sinuses  High blood pressure, elastic rebound forces blood through coronary arteries between contractions

52. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  Right Coronary Artery  Supplies blood to  Right atrium  Portions of both ventricles  Cells of sinoatrial (SA) and atrioventricular nodes  Marginal arteries (surface of right ventricle)  Posterior interventricular artery

53. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  Left Coronary Artery  Supplies blood to  Left ventricle  Left atrium  Interventricular septum

54. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  Two main branches of left coronary artery  Circumflex artery  Anterior interventricular artery  Arterial Anastomoses  Interconnect anterior and posterior interventricular arteries  Stabilize blood supply to cardiac muscle

55. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart  The Cardiac Veins  Great cardiac vein  Drains blood from area of anterior interventricular artery into coronary sinus  Anterior cardiac veins  Empties into right atrium  Posterior cardiac vein, middle cardiac vein, and small cardiac vein  Empty into great cardiac vein or coronary sinus

56. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–9a Coronary Circulation

57. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–9b Coronary Circulation

58. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–9c Coronary Circulation

59. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anatomy of the Heart Figure 20–10 Coronary Circulation and Clinical Testing

60. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Heartbeat  A single contraction of the heart  The entire heart contracts in series  First the atria  Then the ventricles

61. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Two Types of Cardiac Muscle Cells  Conducting system  Controls and coordinates heartbeat  Contractile cells  Produce contractions that propel blood

62. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  The Cardiac Cycle  Begins with action potential at SA node  Transmitted through conducting system  Produces action potentials in cardiac muscle cells (contractile cells)  Electrocardiogram (ECG)  Electrical events in the cardiac cycle can be recorded on an electrocardiogram (ECG)

63. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System Figure 20–11 An Overview of Cardiac Physiology

64. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  A system of specialized cardiac muscle cells  Initiates and distributes electrical impulses that stimulate contraction  Automaticity  Cardiac muscle tissue contracts automatically

65. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Structures of the Conducting System  Sinoatrial (SA) node - wall of right atrium  Atrioventricular (AV) node - junction between atria and ventricles  Conducting cells - throughout myocardium

66. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Conducting Cells  Interconnect SA and AV nodes  Distribute stimulus through myocardium  In the atrium  Internodal pathways  In the ventricles  AV bundle and the bundle branches

67. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Prepotential  Also called pacemaker potential  Resting potential of conducting cells  Gradually depolarizes toward threshold  SA node depolarizes first, establishing heart rate

68. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System Figure 20–12 The Conducting System of the Heart

69. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Heart Rate  SA node generates 80–100 action potentials per minute  Parasympathetic stimulation slows heart rate  AV node generates 40–60 action potentials per minute

70. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  The Sinoatrial (SA) Node  In posterior wall of right atrium  Contains pacemaker cells  Connected to AV node by internodal pathways  Begins atrial activation (Step 1)

71. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System Figure 20–13 Impulse Conduction through the Heart

72. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  The Atrioventricular (AV) Node  In floor of right atrium  Receives impulse from SA node (Step 2)  Delays impulse (Step 3)  Atrial contraction begins

73. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System Figure 20–13 Impulse Conduction through the Heart

74. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System Figure 20–13 Impulse Conduction through the Heart

75. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  The AV Bundle  In the septum  Carries impulse to left and right bundle branches  Which conduct to Purkinje fibers (Step 4)  And to the moderator band  Which conducts to papillary muscles

76. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System Figure 20–13 Impulse Conduction through the Heart

77. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Purkinje Fibers  Distribute impulse through ventricles (Step 5)  Atrial contraction is completed  Ventricular contraction begins

78. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System Figure 20–13 Impulse Conduction through the Heart

79. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Abnormal Pacemaker Function  Bradycardia: abnormally slow heart rate  Tachycardia: abnormally fast heart rate  Ectopic pacemaker  Abnormal cells  Generate high rate of action potentials  Bypass conducting system  Disrupt ventricular contractions

80. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Electrocardiogram (ECG or EKG)  A recording of electrical events in the heart  Obtained by electrodes at specific body locations  Abnormal patterns diagnose damage

81. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Features of an ECG  P wave  Atria depolarize  QRS complex  Ventricles depolarize  T wave  Ventricles repolarize

82. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Time Intervals Between ECG Waves  P–R interval  From start of atrial depolarization  To start of QRS complex  Q–T interval  From ventricular depolarization  To ventricular repolarization

83. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System Figure 20–14a An Electrocardiogram: Electrode Placement for Recording a Standard ECG

84. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System Figure 20–14b An Electrocardiogram: An ECG Printout

85. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Contractile Cells  Purkinje fibers distribute the stimulus to the contractile cells, which make up most of the muscle cells in the heart  Resting Potential  Of a ventricular cell: about –90 mV  Of an atrial cell: about –80 mV

86. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System Figure 20–15 The Action Potential in Skeletal and Cardiac Muscle

87. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System Figure 20–15 The Action Potential in Skeletal and Cardiac Muscle

88. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Refractory Period  Absolute refractory period  Long  Cardiac muscle cells cannot respond  Relative refractory period  Short  Response depends on degree of stimulus

89. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  Timing of Refractory Periods  Length of cardiac action potential in ventricular cell  250–300 msecs: –30 times longer than skeletal muscle fiber –long refractory period prevents summation and tetany

90. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  The Role of Calcium Ions in Cardiac Contractions  Contraction of a cardiac muscle cell is produced by an increase in calcium ion concentration around myofibrils

91. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  The Role of Calcium Ions in Cardiac Contractions  20% of calcium ions required for a contraction  Calcium ions enter plasma membrane during plateau phase  Arrival of extracellular Ca 2+  Triggers release of calcium ion reserves from sarcoplasmic reticulum

92. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  The Role of Calcium Ions in Cardiac Contractions  As slow calcium channels close  Intracellular Ca 2+ is absorbed by the SR  Or pumped out of cell  Cardiac muscle tissue  Very sensitive to extracellular Ca 2+ concentrations

93. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Conducting System  The Energy for Cardiac Contractions  Aerobic energy of heart  From mitochondrial breakdown of fatty acids and glucose  Oxygen from circulating hemoglobin  Cardiac muscles store oxygen in myoglobin

94. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle  Cardiac cycle = The period between the start of one heartbeat and the beginning of the next  Includes both contraction and relaxation

95. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle  Phases of the Cardiac Cycle  Within any one chamber  Systole (contraction)  Diastole (relaxation)

96. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle Figure 20–16 Phases of the Cardiac Cycle

97. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle  Blood Pressure  In any chamber  Rises during systole  Falls during diastole  Blood flows from high to low pressure  Controlled by timing of contractions  Directed by one-way valves

98. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle  Cardiac Cycle and Heart Rate  At 75 beats per minute  Cardiac cycle lasts about 800 msecs  When heart rate increases  All phases of cardiac cycle shorten, particularly diastole

99. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle Eight Steps in the Cardiac Cycle 1.Atrial systole  Atrial contraction begins  Right and left AV valves are open 2.Atria eject blood into ventricles  Filling ventricles 3.Atrial systole ends  AV valves close  Ventricles contain maximum blood volume  Known as end-diastolic volume (EDV)

100. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle Figure 20–17 Pressure and Volume Relationships in the Cardiac Cycle

101. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle Eight Steps in the Cardiac Cycle 4.Ventricular systole  Isovolumetric ventricular contraction  Pressure in ventricles rises  AV valves shut 5.Ventricular ejection  Semilunar valves open  Blood flows into pulmonary and aortic trunks  Stroke volume (SV) = 60% of end-diastolic volume

102. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle Figure 20–17 Pressure and Volume Relationships in the Cardiac Cycle

103. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle Eight Steps in the Cardiac Cycle 6.Ventricular pressure falls  Semilunar valves close  Ventricles contain end-systolic volume (ESV), about 40% of end-diastolic volume 7.Ventricular diastole  Ventricular pressure is higher than atrial pressure  All heart valves are closed  Ventricles relax (isovolumetric relaxation)

104. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle Figure 20–17 Pressure and Volume Relationships in the Cardiac Cycle

105. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle Eight Steps in the Cardiac Cycle 8.Atrial pressure is higher than ventricular pressure  AV valves open  Passive atrial filling  Passive ventricular filling  Cardiac cycle ends The Heart: Cardiac Cycle

106. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle Figure 20–17 Pressure and Volume Relationships in the Cardiac Cycle

107. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle  Heart Sounds  S 1  Loud sounds  Produced by AV valves  S 2  Loud sounds  Produced by semilunar valves  S 3, S 4  Soft sounds  Blood flow into ventricles and atrial contraction

108. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle  Heart Murmur  Sounds produced by regurgitation through valves

109. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cardiac Cycle Figure 20–18 Heart Sounds

110. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  The movement and force generated by cardiac contractions  End-diastolic volume (EDV)  End-systolic volume (ESV)  Stroke volume (SV)  SV = EDV – ESV  Ejection fraction  The percentage of EDV represented by SV  Cardiac output (CO)  The volume pumped by left ventricle in 1 minute

111. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics Figure 20–19 A Simple Model of Stroke Volume

112. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Cardiac Output  CO = HR X SV  CO = cardiac output (mL/min)  HR = heart rate (beats/min)  SV = stroke volume (mL/beat)

113. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Factors Affecting Cardiac Output  Cardiac output  Adjusted by changes in heart rate or stroke volume  Heart rate  Adjusted by autonomic nervous system or hormones  Stroke volume  Adjusted by changing EDV or ESV

114. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics Figure 20–20 Factors Affecting Cardiac Output

115. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Factors Affecting the Heart Rate  Autonomic innervation  Cardiac plexuses: innervate heart  Vagus nerves (X): carry parasympathetic preganglionic fibers to small ganglia in cardiac plexus  Cardiac centers of medulla oblongata: –cardioacceleratory center controls sympathetic neurons (increases heart rate) –cardioinhibitory center controls parasympathetic neurons (slows heart rate)

116. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Autonomic Innervation  Cardiac reflexes  Cardiac centers monitor: –blood pressure (baroreceptors) –arterial oxygen and carbon dioxide levels (chemoreceptors)  Cardiac centers adjust cardiac activity  Autonomic tone  Dual innervation maintains resting tone by releasing ACh and NE  Fine adjustments meet needs of other systems

117. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics Figure 20–21 Autonomic Innervation of the Heart

118. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Effects on the SA Node  Sympathetic and parasympathetic stimulation  Greatest at SA node (heart rate)  Membrane potential of pacemaker cells  Lower than other cardiac cells  Rate of spontaneous depolarization depends on  Resting membrane potential  Rate of depolarization  ACh (parasympathetic stimulation)  Slows the heart  NE (sympathetic stimulation)  Speeds the heart

119. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics Figure 20–22 Autonomic Regulation of Pacemaker Function

120. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Atrial Reflex  Also called Bainbridge reflex  Adjusts heart rate in response to venous return  Stretch receptors in right atrium  Trigger increase in heart rate  Through increased sympathetic activity

121. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Hormonal Effects on Heart Rate  Increase heart rate (by sympathetic stimulation of SA node)  Epinephrine (E)  Norepinephrine (NE)  Thyroid hormone

122. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Factors Affecting the Stroke Volume  The EDV: amount of blood a ventricle contains at the end of diastole  Filling time: –duration of ventricular diastole  Venous return: –rate of blood flow during ventricular diastole

123. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Preload  The degree of ventricular stretching during ventricular diastole  Directly proportional to EDV  Affects ability of muscle cells to produce tension

124. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  The EDV and Stroke Volume  At rest  EDV is low  Myocardium stretches less  Stroke volume is low  With exercise  EDV increases  Myocardium stretches more  Stroke volume increases

125. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  The Frank–Starling Principle  As EDV increases, stroke volume increases  Physical Limits  Ventricular expansion is limited by  Myocardial connective tissue  The cardiac (fibrous) skeleton  The pericardial sac

126. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  End-Systolic Volume (ESV)  The amount of blood that remains in the ventricle at the end of ventricular systole is the ESV

127. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Three Factors That Affect ESV  Preload  Ventricular stretching during diastole  Contractility  Force produced during contraction, at a given preload  Afterload  Tension the ventricle produces to open the semilunar valve and eject blood

128. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Contractility  Is affected by  Autonomic activity  Hormones

129. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Effects of Autonomic Activity on Contractility  Sympathetic stimulation  NE released by postganglionic fibers of cardiac nerves  Epinephrine and NE released by suprarenal (adrenal) medullae  Causes ventricles to contract with more force  Increases ejection fraction and decreases ESV

130. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Effects of Autonomic Activity on Contractility  Parasympathetic activity  Acetylcholine released by vagus nerves  Reduces force of cardiac contractions

131. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Hormones  Many hormones affect heart contraction  Pharmaceutical drugs mimic hormone actions  Stimulate or block beta receptors  Affect calcium ions (e.g., calcium channel blockers)

132. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Afterload  Is increased by any factor that restricts arterial blood flow  As afterload increases, stroke volume decreases

133. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics Figure 20–23 Factors Affecting Stroke Volume

134. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Heart Rate Control Factors  Autonomic nervous system  Sympathetic and parasympathetic  Circulating hormones  Venous return and stretch receptors

135. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Stroke Volume Control Factors  EDV  Filling time  Rate of venous return  ESV  Preload  Contractility  Afterload

136. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  Cardiac Reserve  The difference between resting and maximal cardiac output

137. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics  The Heart and Cardiovascular System  Cardiovascular regulation  Ensures adequate circulation to body tissues  Cardiovascular centers  Control heart and peripheral blood vessels  Cardiovascular system responds to  Changing activity patterns  Circulatory emergencies

138. Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cardiodynamics Figure 20–24 A Summary of the Factors Affecting Cardiac Output