1. 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
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2. 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
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3. Introduction to Cardiovascular System
Capillaries
Also called exchange vessels
Exchange materials between blood and tissues
Materials include dissolved gases, nutrients, wastes
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4. Introduction to Cardiovascular System
Figure 20–1 An Overview of the Cardiovascular System.
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5. 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
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6. 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
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Figure 20–2c

7. 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
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8. Pericarditis An infection of the pericardium
An inflammation of the sac that envelops the heart (pericarditis) causes pain that worsens when the person lies down and decreases when the person sits up and leans forward. Exertion does not increase the pain, but inhaling deeply does. Pain increased by inhaling deeply can also be caused by an inflammation of the membranes covering the lungs (pleurisy).
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9. Anatomy of the Heart
Figure 20–2b The Location of the Heart in the Thoracic Cavity
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10. Anatomy of the Heart
Figure 20–c2 The Location of the Heart in the Thoracic Cavity
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11. Anatomy of the Heart Figure 20–3c The Superficial Anatomy of the Heart
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12. 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
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13. Anatomy of the Heart Figure 20–4 The Heart Wall
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14. Carditis An inflammation of the heart
Can result in valvular heart disease (VHD): (heart disease caused by stenosis of the cardiac valves and obstructed blood flow or caused by degeneration and blood regurgitation)
e.g., rheumatic fever
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15. 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
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16. Anatomy of the Heart Figure 20–5 Cardiac Muscle Cells
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17. Anatomy of the Heart Figure 20–5 Cardiac Muscle Cells
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18. Anatomy of the Heart
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19. 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
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20. 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
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21. Anatomy of the Heart
The Blood Supply to the Heart = Coronary Circulation
Coronary arteries and cardiac veins
Supplies blood to muscle tissue of heart
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22. 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
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23. 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
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24. Anatomy of the Heart Left Coronary Artery Supplies blood to
Left ventricle
Left atrium
Interventricular septum
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25. The Conducting System Heartbeat A single contraction of the heart
The entire heart contracts in series
First the atria
Then the ventricles
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26. The Conducting System Two Types of Cardiac Muscle Cells
Controls and coordinates heartbeat
Contractile cells
Produce contractions that propel blood
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27. 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)
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28. The Conducting System Figure 20–11 An Overview of Cardiac Physiology
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29. The Conducting System A system of specialized cardiac muscle cells
Initiates and distributes electrical impulses that stimulate contraction
Automaticity
Cardiac muscle tissue contracts automatically
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30. 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
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31. 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
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32. The Conducting System Prepotential Also called pacemaker potential
Resting potential of conducting cells
Gradually depolarizes toward threshold
SA node depolarizes first, establishing heart rate
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33. The Conducting System Figure 20–12 The Conducting System of the Heart
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34. 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
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35. The Conducting System
Figure 20–13 Impulse Conduction through the Heart
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36. The Conducting System
Figure 20–13 Impulse Conduction through the Heart
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37. The Conducting System
Figure 20–13 Impulse Conduction through the Heart
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38. The Conducting System
Figure 20–13 Impulse Conduction through the Heart
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39. The Conducting System
Figure 20–13 Impulse Conduction through the Heart
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40. 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
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41. 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
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42. The Conducting System Features of an ECG P wave QRS complex T wave
Atria depolarize
QRS complex
Ventricles depolarize
T wave
Ventricles repolarize
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43. 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
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44. The Conducting System
Figure 20–14a An Electrocardiogram: Electrode Placement for Recording a Standard ECG
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45. The Conducting System
Figure 20–14b An Electrocardiogram: An ECG Printout
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46. 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
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47. The Conducting System
Figure 20–15 The Action Potential in Skeletal and Cardiac Muscle
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48. 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
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49. 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 Ca2+
Triggers release of calcium ion reserves from sarcoplasmic reticulum
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50. The Conducting System The Role of Calcium Ions in Cardiac Contractions
As slow calcium channels close
Intracellular Ca2+ is absorbed by the SR
Or pumped out of cell
Cardiac muscle tissue
Very sensitive to extracellular Ca2+ concentrations
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51. The Cardiac Cycle
Cardiac cycle = The period between the start of one heartbeat and the beginning of the next
Includes both contraction and relaxation
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52. The Cardiac Cycle Phases of the Cardiac Cycle Within any one chamber
Systole (contraction)
Diastole (relaxation)
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53. The Cardiac Cycle Figure 20–16 Phases of the Cardiac Cycle
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54. 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
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55. The Cardiac Cycle Eight Steps in the Cardiac Cycle Atrial systole
Atrial contraction begins
Right and left AV valves are open
Atria eject blood into ventricles
Filling ventricles
Atrial systole ends
AV valves close
Ventricles contain maximum blood volume
Known as end-diastolic volume (EDV)
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56. The Cardiac Cycle
Figure 20–17 Pressure and Volume Relationships in the Cardiac Cycle
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57. The Cardiac Cycle Eight Steps in the Cardiac Cycle Ventricular systole
Isovolumetric ventricular contraction
Pressure in ventricles rises
AV valves shut
Ventricular ejection
Semilunar valves open
Blood flows into pulmonary and aortic trunks
Stroke volume (SV) = 60% of end-diastolic volume
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58. The Cardiac Cycle Eight Steps in the Cardiac Cycle
Ventricular pressure falls
Semilunar valves close
Ventricles contain end-systolic volume (ESV), about 40% of end-diastolic volume
Ventricular diastole
Ventricular pressure is higher than atrial pressure
All heart valves are closed
Ventricles relax (isovolumetric relaxation)
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59. The Cardiac Cycle Eight Steps in the Cardiac Cycle
Atrial pressure is higher than ventricular pressure
AV valves open
Passive atrial filling
Passive ventricular filling
Cardiac cycle ends
The Heart: Cardiac Cycle
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60. The Cardiac Cycle Heart Sounds S1 S2 S3, S4 Loud sounds
Produced by AV valves S2
Produced by semilunar valves
S3, S4
Soft sounds
Blood flow into ventricles and atrial contraction
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61. The Cardiac Cycle Heart Murmur
Sounds produced by regurgitation through valves
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62. Regurgitation Failure of valves Causes backflow of blood into atria
Tricuspid regurgitation (tricuspid incompetence, tricuspid insufficiency) is leakage of blood backward through the tricuspid valve each time the right ventricle contracts.
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63. Tricuspid regurgitation usually results when the right ventricle enlarges and resistance to blood flow from the right ventricle to the lungs is increased. Resistance may be increased by a severe, long-standing lung disorder, such as emphysema or pulmonary hypertension, or by narrowing of the pulmonary valve (pulmonary stenosis). To compensate, the right ventricle enlarges and thickens so that it can pump harder, and the valve opening stretches.
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64. The Cardiac Cycle Figure 20–18 Heart Sounds
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65. 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
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66. Cardiodynamics Figure 20–19 A Simple Model of Stroke Volume
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67. Cardiodynamics Cardiac Output CO = HR X SV
CO = cardiac output (mL/min)
HR = heart rate (beats/min)
SV = stroke volume (mL/beat)
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68. 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
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69. Cardiodynamics Figure 20–20 Factors Affecting Cardiac Output
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70. Cardiodynamics
Figure 20–24 A Summary of the Factors Affecting Cardiac Output
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71. 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)
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72. 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
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73. Cardiodynamics Figure 20–21 Autonomic Innervation of the Heart
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74. 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
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75. 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
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76. Cardiodynamics Hormonal Effects on Heart Rate
Increase heart rate (by sympathetic stimulation of SA node)
Epinephrine (E)
Norepinephrine (NE)
Thyroid hormone
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77. Cardiodynamics Figure 20–23 Factors Affecting Stroke Volume
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78. 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
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