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Essentials of Anatomy and Physiology
Fifth edition
Seeley, Stephens and Tate
Chapter 12: The Heart
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 2.1
The Cardiovascular System
A closed system: heart and blood
vessels
 The heart pumps blood
 Blood vessels allow blood to circulate
A double system:
Pulmonary circuit
Systemic circuit
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.1
The Cardiovascular System
 Functions:
Delivery system for everything!
Remove carbon dioxide and other
waste products
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.1
The Heart
 Location
 Thoracic cavity, between the lungs
 In mediastinum
 Pointed apex directed toward left hip
 2/3 to left of median plane
 Size: About the same as your fist
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.2a
Location and Orientation within the Thorax
Figure 18.2
The Heart: Did You Know…
 A blue whale’s heart may weight 1000
pounds (454,000 grams)
It’s the size of a VW beetle!
 An elephant heart may weigh 75
pounds
Heart rate about 10 bpm
 A mouse’s heart weighs ~ 10 grams
 Heart rate about 250 bpm
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.2a
The Heart: Coverings
 Pericardium – a double serous
membrane
 Visceral pericardium
 On the surface of the heart
 Parietal pericardium
 Lines pericardial cavity
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.3
The Heart: Coverings
The Heart: Coverings
 Pericardial cavity: between layers
Serous fluid fills the space
Fluid required for lubrication
Heart moves!!
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.3
Structure of the Heart – Coverings
Figure 18.3
The Heart Wall
 Three layers
 Epicardium
 Outside layer
 This layer is the visceral pericardium
 Connective tissue layer
 Thin, shiny, slick
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.4
Structure of the Heart Wall
Fig. 12.12
• Epicardium
• = visceral
pericardium
Figure 18.3
The Heart: Heart Wall
 Myocardium
 Middle layer
 Mostly cardiac muscle
 Very thick
 Endocardium
 Inner layer
 Endothelium (Simple squamous E.T)
 Slick, shiny
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.4
Structure of the Heart Wall
Fig. 12.12
• Myocardium
• Endocardium
Figure 18.3
The Heart: Chambers
 Right and left side are separate systems
 Four chambers
 Atria
 Thin walled upper chambers
 Receiving chambers
 Right atrium (-O2 blood)
 Left atrium (+O2 blood)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.6
External Heart Anatomy
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 11.2a
Slide 11.5
The Heart: Chambers
 Ventricles
 Thick walled, lower chambers
 Pumping chambers
 Right ventricle:
to pulmonary circuit (-O2 blood)
 Left ventricle
To systemic circuit (+O2 blood)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.6
External Heart Anatomy
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 11.2a
Slide 11.5
The Heart: Valves
 Function: to direct blood flow
 Two pairs
 Atrioventricular valves – between atria and
ventricles
 Bicuspid (Mitral) valve (left)
 Tricuspid valve (right)
 “Active”: function with cardiac muscle
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.8
Heart Valves
Figure 18.5c
The Heart: Valves
 Semilunar valves between ventricle and
artery
 “Passive”: depend on blood pressure
 Pulmonary semilunar valve
RV to pulmonary trunk
 Aortic semilunar valve
LV to aorta
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.8
Heart Valves
Figure 18.5c
The Heart: Valves
 Valves open as blood is pumped
through
 AV valves held in place by chordae
tendineae (“heart strings”)
 Close to prevent backflow
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.9
Heart Valves
Fig. 12.7
Figure 18.5c
Operation of Heart Valves
Fig. 12.9
Figure 11.4
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.10
The Heart: Associated Great Vessels
 Great Arteries
Aorta
 Leaves left ventricle
 Supplies systemic circuit
Pulmonary trunk (artery)
 Leaves right ventricle
 Supplies pulmonary circuit
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.11
Great Arteries
The Heart: Associated Great Vessels
 Great Veins
Venae cavae (superior, inferior)
 Enter right atrium
 Drain systemic circuit
Pulmonary veins (four)
 Enter left atrium
 Drain pulmonary circuit
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.11
Great Vessels
Figure 18.5c
Coronary Circulation
 The heart muscle has its own blood
supply
Part of systemic circuit
 Coronary arteries (+O2 blood)
 Cardiac veins (-O2 blood)
 Blood returns to the right atrium via the
coronary sinus (-O2 blood)
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Slide 11.12
Coronary Circuit, Anterior View
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Figure 11.2a
Slide 11.5
Coronary Circuit, Posterior View
The Heart: Conduction System
 Intrinsic conduction system
(nodal system)
 Heart muscle cells contract without nerve
impulses
 Heart has an intrinsic rhythm (“built in”)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.13a
The Heart: Conduction System
 Specialized cardiac muscle tissue
 Sinoatrial (SA) node
 Pacemaker
 Atrioventricular (AV) node
 Atrioventricular bundle (of His)
 Bundle branches (R and L)
 Purkinje fibers
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.13b
The Heart: conduction system
Fig. 12.15
Figure 11.5
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Heart Contractions
 Contraction is initiated by the sinoatrial
node: “pacemaker”
 Sends information to all muscle cells of
both atria
 Atria contract simultaneously
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.14a
The Heart: conduction system
Fig. 12.15
Figure 11.5
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Heart Contractions
 Impulse transmission
AV Node serves as “booster station”
Sends impulse through AV bundle,
along bundle branches
Finally to Purkinje fibers
Ventricle muscles contract
simultaneously
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.14a
Heart: conduction system
Figure 11.5
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.14b
The Heart: Cardiac Cycle
 Atria contract simultaneously
 Atria relax, then ventricles contract
Systole = contraction of ventricles
Diastole = relaxation of ventricles
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.16
The Cardiac Cycle
Fig. 12.17
Figure 11.6
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Slide 11.15
ECG
• P wave:
• Atrial depolarization.
• QRS complex:
• Ventricular depolarization.
• Atrial repolarization.
• T wave:
• Ventricular repolarization.
Fig. 12.16
Heart Sounds
• “Lubb-dupp” – sound of valves closing
• First sound “lubb” – the AV valves closing
• Second sound “dupp” – the semilunar valves
closing
The Heart: Cardiac Output
 Cardiac output (CO)
 Amount of blood pumped by each side of
the heart in one minute
 CO = (heart rate) x (stroke volume)
 Stroke volume
 Volume of blood pumped by each ventricle
in one contraction
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.18
Cardiac Output Regulation
Figure 11.7
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 11.19