1. 4 Fluids and Transport Fundamentals of Anatomy & Physiology Unit
Frederic H. Martini
PowerPoint® Lecture Slides prepared by Professor Albia Dugger, Miami–Dade College, Miami, FL
Professor Robert R. Speed, Ph.D., Wallace Community College, Dothan, AL
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings

2. Chapter 20: The Heart

3. How are the cardiovascular system and heart organized?

4. Organization of the Cardiovascular System
PLAY
The Heart: Anatomy
Figure 20–1

5. The Pulmonary Circuit
Carries blood to and from gas exchange surfaces of lungs

6. The Systemic Circuit
Carries blood to and from the body

7. Alternating Circuits
Blood alternates between pulmonary circuit and systemic circuit

8. 3 Types of Blood Vessels Arteries: Veins: Capillaries:
carry blood away from heart
Veins:
carry blood to heart
Capillaries:
networks between arteries and veins

9. Capillaries Also called exchange vessels
Exchange materials between blood and tissues
Dissolved gases, nutrients, wastes

10. 4 Chambers of the Heart 2 for each circuit: left and right:
ventricles and atria

11. 4 Chambers of the Heart Right atrium: Right ventricle:
collects blood from systemic circuit
Right ventricle:
pumps blood to pulmonary circuit

12. 4 Chambers of the Heart Left atrium: Left ventricle:
collects blood from pulmonary circuit
Left ventricle:
pumps blood to systemic circuit

13. Where is the heart located and what are its general features?

14. Anatomy of the Heart Located directly behind sternum
InterActive Physiology: Cardiovascular System: Anatomy Review: The Heart
PLAY
Figure 20–2a

15. Anatomy of the Heart Great veins and arteries at the base
Pointed tip is apex
Figure 20–2c

16. Relation to Thoracic Cavity
Figure 20–2b

17. Relation to Thoracic Cavity
Surrounded by pericardial sac
Between 2 pleural cavities
In the mediastinum

18. What is the structure and function of the pericardium?

19. The Pericardium
Double lining of the pericardial cavity
Figure 20–2c

20. 2 Layers of Pericardium Parietal pericardium: Visceral pericardium:
outer layer
forms inner layer of pericardial sac
Visceral pericardium:
inner layer of pericardium

21. Structures of Pericardium
Pericardial cavity:
Is between parietal and visceral layers
contains pericardial fluid
Pericardial sac:
fibrous tissue
surrounds and stabilizes heart

22. Pericarditis
An infection of the pericardium

23. Superficial Anatomy of the Heart
4 cardiac chambers
Figure 20–3

24. Atria
Thin-walled
Expandable outer auricle

25. Sulci Coronary sulcus: Anterior and posterior interventricular sulci:
divides atria and ventricles
Anterior and posterior interventricular sulci:
separate left and right ventricles
contain blood vessels of cardiac muscle

26. What are the layers of the heart wall?

27. The Heart Wall
Figure 20–4

28. 3 Layers of the Heart Wall
Epicardium:
outer layer
Myocardium:
middle layer
Endocardium:
inner layer

29. Epicardium
Visceral pericardium
Covers the heart

30. Myocardium Muscular wall of the heart
Concentric layers of cardiac muscle tissue

31. Cardiac Muscle Cells
Figure 20–5

32. Cardiac Muscle Cells Intercalated discs:
interconnect cardiac muscle cells
secured by desmosomes
linked by gap junctions
convey force of contraction
propagate action potentials

33. Characteristics of Cardiac Muscle Cells
Small size
Single, central nucleus
Branching interconnections between cells
Intercalated discs

34. Cardiac Cells vs. Skeletal Fibers
Table 20-1

35. What is the path of blood flow through the heart, and what are the major blood vessels, chambers, and heart valves?

36. Internal Anatomy
PLAY
3D Panorama of the Heart
Figure 20–6a

37. Atrioventricular (AV) Valves
Connect right atrium to right ventricle and left atrium to left ventricle
Permit blood flow in 1 direction:
atria to ventricles
PLAY
The Heart: Valves

38. Septa Interatrial septum: Interventricular septum: separates atria
separates ventricles

39. The Vena Cava Delivers systemic circulation to right atrium
Superior vena cava:
receives blood from head, neck, upper limbs, and chest
Inferior vena cava:
receives blood from trunk, and viscera, lower limbs

40. Coronary Sinus Cardiac veins return blood to coronary sinus
Coronary sinus opens into right atrium

41. Foramen Ovale Before birth, is an opening through interatrial septum
Connects the 2 atria
Seals off at birth, forming fossa ovalis

42. Pectinate Muscles Contain prominent muscular ridges
On anterior atrial wall
And inner surfaces of right auricle

43. Cusps Fibrous flaps that form bicuspid (2) and tricuspid (3) valves
Free edges attach to chordae tendineae from papillary muscles of ventricle
Prevent valve from opening backward

44. Right Atrioventricular (AV) Valve
Also called tricuspid valve
Opening from right atrium to right ventricle
Has 3 cusps
Prevents backflow
PLAY
The Heart: Blood Flow

45. Trabeculae Carneae
Muscular ridges on internal surface of right ventricle
Includes moderator band:
ridge contains part of conducting system
coordinates contractions of cardiac muscle cells

46. The Pulmonary Circuit
Conus arteriosus (superior 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 3 semilunar cusps

47. Return from Pulmonary Circuit
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
2-cusp bicuspid valve or mitral valve

48. 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

49. The Left Ventricle Systemic circulation:
blood leaves left ventricle through aortic valve into ascending aorta
ascending aorta turns (aortic arch) and becomes descending aorta

50. Left and Right Ventricles
Have significant structural differences
Figure 20–7

51. Structure of Left and Right Ventricles
Right ventricle wall is thinner, develops less pressure than left ventricle
Right ventricle is pouch-shaped, left ventricle is round

52. The Heart Valves One-way valves prevent backflow during contraction
Figure 20–8

53. 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

54. Regurgitation
Failure of valves
Causes backflow of blood into atria

55. Semilunar Valves Pulmonary and aortic tricuspid valves
Prevent backflow from pulmonary trunk and aorta into ventricles
Have no muscular support
3 cusps support like tripod

56. Aortic Sinuses At base of ascending aorta
Prevent valve cusps from sticking to aorta
Origin of right and left coronary arteries

57. Carditis An inflammation of the heart
Can result in valvular heart disease (VHD):
e.g., rheumatic fever

58. KEY CONCEPT (1 of 3) The heart has 4 chambers:
2 for pulmonary circuit:
right atrium and right ventricle
2 for systemic circuit:
left atrium and left ventricle

59. KEY CONCEPT (2 of 3) Left ventricle has a greater workload
Is much more massive than right ventricle, but the two chambers pump equal amounts of blood

60. KEY CONCEPT (3 of 3)
AV valves prevent backflow from ventricles into atria
Semilunar valves prevent backflow from aortic and pulmonary trunks into ventricles

61. Connective Tissue Fibers of the Heart
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

62. The Fibrous Skeleton
4 bands around heart valves and bases of pulmonary trunk and aorta
Stabilize valves
Electrically insulate ventricular cells from atrial cells

63. How is the heart supplied with blood?

64. Blood Supply to the Heart
Coronary circulation
Figure 20–9

65. Coronary Circulation Coronary arteries and cardiac veins
Supplies blood to muscle tissue of heart

66. Coronary Arteries Left and right Originate at aortic sinuses
High blood pressure, elastic rebound force blood through coronary arteries between contractions

67. 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

68. Left Coronary Artery Supplies blood to: left ventricle left atrium
interventricular septum

69. Cardiac Veins (1 of 3) Great cardiac vein:
drains blood from area of anterior interventricular artery into coronary sinus

70. Cardiac Veins (2 of 3) Anterior cardiac vein:
empties into right atrium

71. Cardiac Veins (3 of 3)
Posterior cardiac vein, middle cardiac vein, and small cardiac vein:
empty into great cardiac vein or coronary sinus

72. The Cardiac Cycle
Figure 20–11

73. The Heartbeat A single contraction of the heart
The entire heart contracts in series:
first the atria
then the ventricles

74. 2 Types of Cardiac Muscle Cells
Conducting system:
controls and coordinates heartbeat
Contractile cells:
produce contractions

75. The Cardiac Cycle Begins with action potential at SA node
transmitted through conducting system
produces action potentials in cardiac muscle cells (contractile cells)
InterActive Physiology: Cardiovascular System: Cardiac Action Potential
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76. Electrocardiogram (ECG)
Electrical events in the cardiac cycle can be recorded on an electrocardiogram (ECG)

77. What is the difference between nodal cells and conducting cells; what are the components and functions of the conducting system of the heart?

78. The Conducting System
Figure 20–12

79. The Conducting System A system of specialized cardiac muscle cells:
initiates and distributes electrical impulses that stimulate contraction
Automaticity:
cardiac muscle tissue contracts automatically

80. Structures of the Conducting System
Sinoatrial (SA) node
Atrioventricular (AV) node
Conducting cells

81. Conducting Cells Interconnect SA and AV nodes
Distribute stimulus through myocardium
In the atrium:
internodal pathways
In the ventricles:
AV bundle and bundle branches

82. Prepotential Also called pacemaker potential
Resting potential of conducting cells:
gradually depolarizes toward threshold
SA node depolarizes first, establishing heart rate

83. 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

84. Impulse Conduction through the Heart
Figure 20–13

85. 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)

86. The Atrioventricular (AV) Node
In floor of right atrium
Receives impulse from SA node (Step 2)
Delays impulse (Step 3)
Atrial contraction begins

87. 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

88. 4. The Purkinje Fibers Distribute impulse through ventricles (Step 5)
Atrial contraction is completed
Ventricular contraction begins

89. Abnormal Pacemaker Function
Bradycardia:
abnormally slow heart rate
Tachycardia:
abnormally fast heart rate

90. Ectopic Pacemaker Abnormal cells
Generate high rate of action potentials
Bypass conducting system
Disrupt ventricular contractions

91. What electrical events are associated with a normal electrocardiogram?

92. The Electrocardiogram
Figure 20–14b

93. Electrocardiogram (ECG or EKG)
A recording of electrical events in the heart
Obtained by electrodes at specific body locations
Abnormal patterns diagnose damage

94. Features of an ECG P wave: QRS complex: T wave: atria depolarize
ventricles depolarize
T wave:
ventricles repolarize

95. Cardiac Arrhythmias
Abnormal patterns of cardiac electrical activity

96. KEY CONCEPT (1 of 3)
Heart rate is normally established by cells of SA node
Rate can be modified by autonomic activity, hormones, and other factors

97. KEY CONCEPT (2 of 3)
From the SA node, stimulus is conducted to AV node, AV bundle, bundle branches, and Purkinje fibers before reaching ventricular muscle cells

98. KEY CONCEPT (3 of 3)
Electrical events associated with the heartbeat can be monitored in an electrocardiogram (ECG)

99. Contractile Cells
Purkinje fibers distribute the stimulus to the contractile cells, which make up most of the muscle cells in the heart

100. What events take place during an action potential in cardiac muscle?

101. Action Potentials in Skeletal and Cardiac Muscle
Figure 20–15

102. Resting Potential Of a ventricular cell: Of an atrial cell:
about —90 mV
Of an atrial cell:
about —80 mV

103. 3 Steps of Cardiac Action Potential
Rapid depolarization:
voltage-regulated sodium channels (fast channels) open

104. 3 Steps of Cardiac Action Potential
As sodium channels close:
voltage-regulated calcium channels (slow channels) open
balance Na+ ions pumped out
hold membrane at 0 mV plateau

105. 3 Steps of Cardiac Action Potential
Repolarization:
plateau continues
slow calcium channels close
slow potassium channels open
rapid repolarization restores resting potential

106. 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

107. What is the importance of calcium ions to the contractile process?

108. Calcium and Contraction
Contraction of a cardiac muscle cell is produced by an increase in calcium ion concentration around myofibrils

109. 2 Steps of Calcium Ion Concentration
20% of calcium ions required for a contraction:
calcium ions enter cell membrane during plateau phase

110. 2 Steps of Calcium Ion Concentration
Arrival of extracellular Ca2+:
triggers release of calcium ion reserves from sarcoplasmic reticulum

111. Intracellular and Extracellular Calcium
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

112. What events take place during the cardiac cycle, including atrial and ventricular systole and diastole?

113. The Cardiac Cycle
The period between the start of 1 heartbeat and the beginning of the next
Includes both contraction and relaxation
InterActive Physiology: Cardiovascular System: The Cardiac Cycle
PLAY

114. 2 Phases of the Cardiac Cycle
Within any 1 chamber:
systole (contraction)
diastole (relaxation)

115. Blood Pressure In any chamber: Blood flows from high to low pressure:
rises during systole
falls during diastole
Blood flows from high to low pressure:
controlled by timing of contractions
directed by one-way valves

116. Phases of the Cardiac Cycle
Figure 20–16

117. 4 Phases of the Cardiac Cycle
Atrial systole
Atrial diastole
Ventricular systole
Ventricular diastole

118. 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

119. Pressure and Volume in the Cardiac Cycle
8 steps in the cardiac cycle
Figure 20–17

120. 8 Steps in the Cardiac Cycle
Atrial systole:
atrial contraction begins
right and left AV valves are open

121. 8 Steps in the Cardiac Cycle
Atria eject blood into ventricles:
filling ventricles

122. 8 Steps in the Cardiac Cycle
Atrial systole ends:
AV valves close
ventricles contain maximum volume
end-diastolic volume (EDV)

123. 8 Steps in the Cardiac Cycle
Ventricular systole:
isovolemic ventricular contraction
pressure in ventricles rises
AV valves shut

124. 8 Steps in the Cardiac Cycle
Ventricular ejection:
semilunar valves open
blood flows into pulmonary and aortic trunks
Stroke volume (SV) = 60% of end-diastolic volume

125. 8 Steps in the Cardiac Cycle
Ventricular pressure falls:
semilunar valves close
ventricles contain end-systolic volume (ESV), about 40% of end-diastolic volume

126. 8 Steps in the Cardiac Cycle
Ventricular diastole:
ventricular pressure is higher than atrial pressure
all heart valves are closed
ventricles relax (isovolumetric relaxation)

127. 8 Steps in the Cardiac Cycle
Atrial pressure is higher than ventricular pressure:
AV valves open
passive atrial filling
passive ventricular filling
cardiac cycle ends
PLAY
The Heart: Cardiac Cycle

128. Heart Failure
Lack of adequate blood flow to peripheral tissues and organs due to ventricular damage

129. How do heart sounds relate to specific events in the cardiac cycle?

130. Heart Sounds
Figure 20–18b

131. 4 Heart Sounds S1: S2: S3, S4: loud sounds produced by AV valves
produced by semilunar valves
S3, S4:
soft sounds
blood flow into ventricles and atrial contraction

132. Positioning the Stethoscope
To detect sounds of each valve
Figure 20–18a

133. Heart Murmur
Sounds produced by regurgitation through valves

134. What is cardiac output, and what factors influence it?

135. Cardiodynamics
The movement and force generated by cardiac contractions
InterActive Physiology: Cardiovascular System: Cardiac Output
PLAY

136. Important Cardiodynamics Terms
End-diastolic volume (EDV)
End-systolic volume (ESV)
Stroke volume (SV):
SV = EDV — ESV

137. Important Cardiodynamics Terms
Ejection fraction:
the percentage of EDV represented by SV
Cardiac output (CO):
the volume pumped by each ventricle in 1 minute

138. Stroke Volume
Volume (ml) of blood ejected per beat
Figure 20–19

139. Cardiac Output Cardiac output (CO) ml/min =
Heart rate (HR) beats/min 
Stroke volume (SV) ml/beat

140. Adjusting to Conditions
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

141. What variables influence heart rate?

142. Autonomic Innervation
Figure 20–21 (Navigator)

143. Autonomic Innervation (1 of 4)
Cardiac plexuses:
innervate heart
Vagus nerves (X):
carry parasympathetic preganglionic fibers to small ganglia in cardiac plexus

144. Autonomic Innervation (2 of 4)
Cardiac centers of medulla oblongata:
cardioacceleratory center:
controls sympathetic neurons (increase heart rate)
cardioinhibitory center:
controls parasympathetic neurons (slow heart rate)

145. Autonomic Innervation (3 of 4)
Cardiac reflexes:
Cardiac centers monitor:
baroreceptors (blood pressure)
chemoreceptors (arterial oxygen and carbon dioxide levels)
Cardiac centers adjust cardiac activity

146. Autonomic Innervation (4 of 4)
Autonomic tone:
dual innervation maintains resting tone by releasing Ach and NE
fine adjustments meet needs of other systems

147. Autonomic Pacemaker Regulation
Figure 20–22

148. Autonomic Pacemaker Regulation (1 of 3)
Sympathetic and parasympathetic stimulation:
greatest at SA node (heart rate)
Membrane potential of pacemaker cells:
lower than other cardiac cells

149. Autonomic Pacemaker Regulation (2 of 3)
Rate of spontaneous depolarization depends on:
resting membrane potential
rate of depolarization

150. Autonomic Pacemaker Regulation (3 of 3)
ACh (parasympathetic stimulation):
slows the heart
NE (sympathetic stimulation):
speeds the heart

151. 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

152. Hormonal Effects on Heart Rate
Increase heart rate (by sympathetic stimulation of SA node):
epinephrine (E)
norepinephrine (NE)
thyroid hormone

153. What variables influence stroke volume?

154. Hormones and Contractility
Many hormones affect heart contraction
Pharmaceutical drugs mimic hormone actions:
stimulate or block beta receptors
affect calcium ions e.g., calcium channel blockers

155. How are adjustments in stroke volume and cardiac output coordinated at different levels of activity?

156. Factors Affecting Heart Rate and Stroke Volume
Figure 20–24

157. Heart Rate Control Factors
Autonomic nervous system:
sympathetic and parasympathetic
Circulating hormones
Venous return and stretch receptors

158. KEY CONCEPT (1 of 2) Cardiac output:
the amount of blood pumped by the left ventricle each minute
adjusted by the ANS in response to:
circulating hormones
changes in blood volume
alterations in venous return

159. KEY CONCEPT (2 of 2)
Most healthy people can increase cardiac output by 300–500%

160. The Heart and Cardiovascular System
Cardiovascular regulation:
ensures adequate circulation to body tissues
Cardiovascular centers:
control heart and peripheral blood vessels

161. The Heart and Cardiovascular System
Cardiovascular system responds to:
changing activity patterns
circulatory emergencies

162. SUMMARY (1 of 7) Organization of cardiovascular system:
pulmonary and systemic circuits
3 types of blood vessels:
arteries, veins, and capillaries

163. SUMMARY (2 of 7) 4 chambers of the heart: left and right atria
left and right ventricles

164. SUMMARY (3 of 7) Pericardium, mediastinum, and pericardial sac
Coronary sulcus and superficial anatomy of the heart
Structures and cells of the heart wall

165. SUMMARY (4 of 7) Internal anatomy and structures of the heart:
septa, muscles, and blood vessels
Valves of the heart and direction of blood flow
Connective tissues of the heart

166. SUMMARY (5 of 7) Coronary blood supply
Contractile cells and the conducting system:
pacemaker calls, nodes, bundles, and Purkinje fibers

167. SUMMARY (6 of 7) Electrocardiogram and its wave forms
Refractory period of cardiac cells
Cardiac cycle:
atrial and ventricular
systole and diastole

168. SUMMARY (7 of 7) Cardiodynamics: Control of cardiac output
stroke volume and cardiac output
Control of cardiac output