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Cardiovascular
The
Cardiovascular
System
System: The
Heart: Part A
The Pulmonary and Systemic
Circuits
 Heart is transport system; two
side-by-side pumps
 Pulmonary Circuit
 Right side receives oxygen-poor blood from tissues
 Pumps to lungs to get rid of CO2, pick up O2
 Systemic Circuit
 Left side receives oxygenated blood from lungs
 Pumps to body tissues
© 2013 Pearson Education, Inc.
The Pulmonary and Systemic
Circuits
 Receiving chambers of heart:
 Right atrium
 Receives blood returning from systemic circuit
 Left atrium
 Receives blood returning from pulmonary circuit
© 2013 Pearson Education, Inc.
The Pulmonary and Systemic
Circuits
 Pumping chambers of heart:
 Right ventricle
 Pumps blood through pulmonary circuit
 Left ventricle
 Pumps blood through systemic circuit
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Figure 18.1 The systemic and pulmonary circuits.
Capillary beds of
lungs where gas
exchange occurs
Pulmonary Circuit
Pulmonary
arteries
Aorta and branches
Venae
cavae
Right
atrium
Right
ventricle
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Oxygen-rich,
CO2-poor blood
Oxygen-poor,
CO2-rich blood
Pulmonary veins
Left
atrium
Heart
Left
ventricle
Systemic Circuit
Capillary beds of all
body tissues where
gas exchange occurs
Heart Anatomy
 Approximately size of fist
 Location:
 In mediastinum between second rib and fifth
intercostal space
 Two-thirds of heart to left of midsternal line
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 Base (posterior surface) leans toward right shoulder
Heart Anatomy
 Apex points toward left hip
 Apical impulse palpated between fifth and sixth ribs, just below
left nipple
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Figure 18.2a Location of the heart in the mediastinum.
Midsternal line
2nd rib
Sternum
Diaphragm
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Location of
apical impulse
Figure 18.2b Location of the heart in the mediastinum.
Mediastinum
Heart
Left lung
Body of T7
vertebra
Posterior
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Superior
vena cava
Pulmonary
trunk
Aorta
Parietal pleura
(cut)
Left lung
Pericardium (cut)
Apex of heart
Diaphragm
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Coverings of the Heart:
Pericardium
 Double-walled sac
 Superficial fibrous pericardium
 Protects, anchors to surrounding structures, and
prevents overfilling
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Pericardium
 Deep two-layered serous pericardium
 Parietal layer lines internal surface of fibrous
pericardium
 Visceral layer (epicardium) on external surface of
heart
 Two layers separated by fluid-filled pericardial
cavity (decreases friction)
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Pulmonary
trunk
Fibrous pericardium
Pericardium
Parietal layer of serous
pericardium
Myocardium
Pericardial cavity
Epicardium (visceral
layer of serous
pericardium)
Myocardium
Endocardium
Heart chamber
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Heart
wall
Homeostatic Imbalance
 Pericarditis
 Inflammation of pericardium
 Roughens membrane surfaces  pericardial friction
rub (creaking sound) heard with stethoscope
 Cardiac tamponade
 Excess fluid sometimes compresses heart  limited
pumping ability
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Layers of the Heart Wall
 Three layers of heart wall:
 Epicardium
 Myocardium
 Endocardium
 Epicardium
 Visceral layer of serous pericardium
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Layers of the Heart Wall
 Myocardium
 Spiral bundles of contractile cardiac muscle cells
 Cardiac skeleton: crisscrossing, interlacing layer of
connective tissue
 Anchors cardiac muscle fibers
 Supports great vessels and valves
 Limits spread of action potentials to specific paths
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Layers of the Heart Wall
 Endocardium continuous with endothelial lining
of blood vessels
 Lines heart chambers; covers cardiac skeleton of
valves
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Pulmonary
trunk
Fibrous pericardium
Pericardium
Parietal layer of serous
pericardium
Myocardium
Pericardial cavity
Epicardium (visceral
layer of serous
pericardium)
Myocardium
Endocardium
Heart chamber
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Heart
wall
Cardiac
muscle
bundles
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Chambers
 Four chambers:
 Two superior atria
 Two inferior ventricles
 Interatrial septum – separates atria
 Fossa ovalis – remnant of foramen ovale of fetal
heart
 Interventricular septum – separates ventricles
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Aorta
Superior vena cava
Right pulmonary artery
Pulmonary trunk
Right atrium
Right pulmonary veins
Fossa ovalis
Pectinate muscles
Tricuspid valve
Right ventricle
Chordae tendineae
Trabeculae carneae
Inferior vena cava
Frontal section
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Left pulmonary artery
Left atrium
Left pulmonary veins
Mitral (bicuspid) valve
Aortic valve
Pulmonary valve
Left ventricle
Papillary muscle
Interventricular septum
Epicardium
Myocardium
Endocardium
Chambers and Associated
Great Vessels
 Coronary sulcus (atrioventricular groove)
 Encircles junction of atria and ventricles
 Anterior interventricular sulcus
 Anterior position of interventricular septum
 Posterior interventricular sulcus
 Landmark on posteroinferior surface
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Atria: The Receiving
Chambers
 Auricles
 Appendages that increase atrial volume
 Right atrium
 Pectinate muscles
 Posterior and anterior regions separated by crista
terminalis
 Left atrium
 Pectinate muscles only in auricles
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Atria: The Receiving Chambers
 Small, thin-walled
 Contribute little to propulsion of blood
 Three veins empty into right atrium:
 Superior vena cava, inferior vena cava, coronary
sinus
 Four pulmonary veins empty into left atrium
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Ventricles: The Discharging Chambers
 Most of the volume of heart
 Right ventricle - most of anterior surface
 Left ventricle – posteroinferior surface
 Trabeculae carneae – irregular ridges of muscle
on walls
 Papillary muscles – anchor chordae tendineae
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Ventricles: The Discharging
Chambers
 Thicker walls than atria
 Actual pumps of heart
 Right ventricle
 Pumps blood into pulmonary trunk
 Left ventricle
 Pumps blood into aorta (largest artery in body)
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Brachiocephalic trunk
Superior vena cava
Right pulmonary artery
Ascending aorta
Pulmonary trunk
Right pulmonary veins
Left common carotid artery
Left subclavian artery
Aortic arch
Ligamentum arteriosum
Left pulmonary artery
Left pulmonary veins
Auricle of
left atrium
Right atrium
Right coronary artery
(in coronary sulcus)
Anterior cardiac vein
Right ventricle
Circumflex artery
Right marginal artery
Great cardiac vein
Anterior interventricular
artery (in anterior
interventricular sulcus)
Apex
Small cardiac vein
Inferior vena cava
Anterior view
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Left coronary artery
(in coronary sulcus)
Left ventricle
Aortic arch (fat covered)
Pulmonary trunk
Auricle of right atrium
Auricle of left atrium
Anterior interventricular
artery
Right ventricle
Apex of heart (left ventricle)
Anterior aspect (pericardium removed)
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Superior vena cava
Ascending aorta (cut open)
Pulmonary trunk
Aortic valve
Right ventricle anterior
wall (retracted)
Opening to right
atrium
Pulmonary valve
Interventricular
septum (cut)
Left ventricle
Chordae tendineae
Papillary muscles
Trabeculae carneae
Right ventricle
Photograph; view similar to (e)
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Heart Valves
 Ensure unidirectional blood flow through
heart
 Open and close in response to pressure
changes
 Two atrioventricular (AV) valves
 Prevent backflow into atria when ventricles
contract
 Tricuspid valve (right AV valve)
 Mitral valve (left AV valve, bicuspid valve)
 Chordae tendineae anchor cusps to papillary
muscles
 Hold valve flaps in closed position
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Figure 18.7 The atrioventricular (AV) valves.
1 Blood returning to the heart fills
atria, pressing against the AV valves.
The increased pressure forces AV
valves open.
Direction of
blood flow
Atrium
2 As ventricles fill, AV valve flaps
hang limply into ventricles.
Cusp of
atrioventricular
valve (open)
Chordae
tendineae
3 Atria contract, forcing additional
blood into ventricles.
Ventricle
Papillary
muscle
AV valves open; atrial pressure greater than ventricular pressure
Atrium
1 Ventricles contract, forcing
blood against AV valve cusps.
2 AV valves close.
3 Papillary muscles contract and
chordae tendineae tighten,
preventing valve flaps from everting
into atria.
AV valves closed; atrial pressure less than ventricular pressure
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Cusps of
atrioventricular
valve (closed)
Blood in
ventricle
Heart Valves
 Two semilunar (SL) valves
 Prevent backflow into ventricles when ventricles
relax
 Open and close in response to pressure changes
 Aortic semilunar valve
 Pulmonary semilunar valve
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Figure 18.8 The semilunar (SL) valves.
Aorta
Pulmonary
trunk
As ventricles contract
and intraventricular
pressure rises, blood
is pushed up against
semilunar valves,
forcing them open.
Semilunar valves open
As ventricles relax
and intraventricular
pressure falls, blood
flows back from
arteries, filling the
cusps of semilunar
valves and forcing
them to close.
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Semilunar valves closed
Figure 18.6a Heart valves.
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Myocardium
Mitral
(left atrioventricular)
valve
Tricuspid
(right atrioventricular)
valve
Aortic valve
Pulmonary valve
Cardiac
skeleton
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Anterior
Figure 18.6b Heart valves.
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Myocardium
Mitral
(left atrioventricular)
valve
Tricuspid
(right atrioventricular)
valve
Aortic valve
Pulmonary valve
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Figure 18.6c Heart valves.
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Chordae tendineae attached
to tricuspid valve flap
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Papillary
muscle
Figure 18.6d Heart valves.
Pulmonary valve
Aortic valve
Area of cutaway
Mitral valve
Tricuspid valve
Opening of inferior
vena cava
Tricuspid valve
Mitral valve
Chordae
tendineae
Myocardium
of right
ventricle
Interventricular
septum
Papillary
muscles
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Myocardium
of left ventricle
Homeostatic Imbalance
 Two conditions severely weaken heart:
 Incompetent valve
 Blood backflows so heart repumps same blood
over and over
 Valvular stenosis
 Stiff flaps – constrict opening  heart must exert
more force to pump blood
 Valve replaced with mechanical, animal, or
cadaver valve
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Pathway of Blood Through the
Heart
 Pulmonary circuit
 Right atrium  tricuspid valve  right ventricle
 Right ventricle  pulmonary semilunar valve 
pulmonary trunk  pulmonary arteries  lungs
 Lungs  pulmonary veins  left atrium
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Pathway of Blood Through
the Heart
 Systemic circuit
 Left atrium  mitral valve  left ventricle
 Left ventricle  aortic semilunar valve  aorta
 Aorta  systemic circulation
Both sides of the heart pump at the same time, but
Oxygen-poor blood
let’s follow one spurt of blood all the way through the
Oxygen-rich blood
system.
Pulmonary
Tricuspid
Semilunar
valve
Superior vena cava (SVC)
valve
Right
Pulmonary
Right
Inferior vena cava (IVC)
Coronary sinus
ventricle
trunk
atrium
SVC
Pulmonary
arteries
Pulmonary
trunk
Tricuspid
valve
Coronary
sinus
Right
atrium
Pulmonary
semilunar
valve
Right
ventricle
IVC
To heart
Oxygen-poor blood
returns from the body
tissues back to the heart.
Oxygen-poor blood is carried
in two pulmonary arteries to
the lungs (pulmonary circuit)
to be oxygenated.
Systemic
capillaries
To body
Pulmonary
capillaries
Oxygen-rich blood is
delivered to the body
tissues (systemic circuit).
Oxygen-rich blood returns
to the heart via the four
To heart
pulmonary veins.
Aorta
Pulmonary
veins
© 2013 Pearson Education, Inc.
Aorta
Left
atrium
Mitral
valve
Left
ventricle
Aortic
semilunar
valve
Aortic
Semilunar
valve
To lungs
Left
ventricle
Mitral
valve
Left
atrium
Four
pulmonary
veins
Slide 1
Figure 18.9 The heart is a double pump, each side supplying its own circuit.
Superior vena cava (SVC)
Inferior vena cava (IVC)
Coronary sinus
SVC
IVC
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Slide 2
Oxygen-poor blood
Oxygen-rich blood
Coronary
sinus
Figure 18.9 The heart is a double pump, each side supplying its own circuit.
Superior vena cava (SVC)
Inferior vena cava (IVC)
Coronary sinus
SVC
Right
atrium
Coronary
sinus
Right
atrium
IVC
© 2013 Pearson Education, Inc.
Slide 3
Oxygen-poor blood
Oxygen-rich blood
Figure 18.9 The heart is a double pump, each side supplying its own circuit.
Superior vena cava (SVC)
Inferior vena cava (IVC)
Coronary sinus
SVC
Right
atrium
Coronary
sinus
Tricuspid
valve
Tricuspid
valve
Right
atrium
IVC
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Right
ventricle
Slide 4
Right
ventricle
Oxygen-poor blood
Oxygen-rich blood
Figure 18.9 The heart is a double pump, each side supplying its own circuit.
Superior vena cava (SVC)
Inferior vena cava (IVC)
Coronary sinus
Right
atrium
Tricuspid
valve
Right
ventricle
Pulmonary
Semilunar
valve
Pulmonary
arteries
SVC
Coronary
sinus
Tricuspid
valve
Right
atrium
Right
ventricle
IVC
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Pulmonary
trunk
Pulmonary
semilunar
valve
Slide 5
Pulmonary
trunk
Oxygen-poor blood
Oxygen-rich blood
Figure 18.9 The heart is a double pump, each side supplying its own circuit.
Slide 6
Oxygen-poor blood
Superior vena cava (SVC)
Inferior vena cava (IVC)
Coronary sinus
Right
atrium
Tricuspid
valve
Right
ventricle
Pulmonary
Semilunar
valve
Oxygen-rich blood
Pulmonary
trunk
Pulmonary
arteries
SVC
Coronary
sinus
Tricuspid
valve
Right
atrium
IVC
Right
ventricle
Pulmonary
trunk
Pulmonary
semilunar
valve
Oxygen-poor blood is carried
in two pulmonary arteries to the
lungs (pulmonary circuit)
to be oxygenated.
Pulmonary
capillaries
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To lungs
Slide 7
Oxygen-poor blood
Oxygen-rich blood
Pulmonary
veins
Four
pulmonary
veins
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Figure 18.9 The heart is a double pump, each side supplying its own circuit.
Blood Flow Through the Heart
Oxygen-poor blood
Oxygen-rich blood
Pulmonary
veins
Right
ventricle
Left
atrium
Left
atrium
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Four
pulmonary
veins
Slide 8
Figure 18.9 The heart is a double pump, each side supplying its own circuit.
Slide 9
Oxygen-poor blood
Oxygen-rich blood
Pulmonary
veins
Left
atrium
Mitral
valve
Left
ventricle
Left
ventricle
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Mitral
valve
Left
atrium
Four
pulmonary
veins
Figure 18.9 The heart is a double pump, each side supplying its own circuit.
Slide 10
Oxygen-poor blood
Oxygen-rich blood
Right
ventricle
Aorta
Pulmonary
veins
Aortic
semilunar
valve
Aorta
Aortic
Semilunar
valve
© 2013 Pearson Education, Inc.
Left
atrium
Mitral
valve
Left
ventricle
Left
ventricle
Mitral
valve
Left
atrium
Four
pulmonary
veins
Figure 18.9 The heart is a double pump, each side supplying its own circuit.
Slide 11
Blood Flow Through the Heart
Oxygen-poor blood
Oxygen-rich blood
Systemic
capillaries
To body
Oxygen-rich blood is
delivered to the body
tissues (systemic
circuit).
Aorta
Pulmonary
veins
Aortic
semilunar
valve
Aorta
Aortic
Semilunar
valve
© 2013 Pearson Education, Inc.
Left
atrium
Mitral
valve
Left
ventricle
Left
ventricle
Mitral
valve
Left
atrium
Four
pulmonary
veins
Figure 18.9 The heart is a double pump, each side supplying its own circuit.
Both sides of the heart pump at the same time, but
Oxygen-poor blood
let’s follow one spurt of blood all the way through the
Oxygen-rich blood
system.
Pulmonary
Tricuspid
Semilunar
valve
Superior vena cava (SVC)
valve
Right
Pulmonary
Right
Inferior vena cava (IVC)
Coronary sinus
ventricle
trunk
atrium
SVC
Pulmonary
arteries
Pulmonary
trunk
Tricuspid
valve
Coronary
sinus
Right
atrium
Pulmonary
semilunar
valve
Right
ventricle
IVC
To heart
Oxygen-poor blood
returns from the body
tissues back to the heart.
Oxygen-poor blood is carried
in two pulmonary arteries to
the lungs (pulmonary circuit)
to be oxygenated.
Systemic
capillaries
To body
Pulmonary
capillaries
Oxygen-rich blood is
delivered to the body
tissues (systemic circuit).
Oxygen-rich blood returns
to the heart via the four
To heart
pulmonary veins.
Aorta
Pulmonary
veins
© 2013 Pearson Education, Inc.
Aorta
Left
atrium
Mitral
valve
Left
ventricle
Aortic
semilunar
valve
Aortic
Semilunar
valve
To lungs
Left
ventricle
Mitral
valve
Left
atrium
Four
pulmonary
veins
Slide 12
Pathway of Blood Through
the Heart
 Equal volumes of blood pumped to pulmonary
and systemic circuits
 Pulmonary circuit short, low-pressure circulation
 Systemic circuit long, high-friction circulation
 Anatomy of ventricles reflects differences
 Left ventricle walls 3X thicker than right
 Pumps with greater pressure
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Figure 18.10 Anatomical differences between the right and left ventricles.
Left
ventricle
Right
ventricle
Interventricular
septum
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Coronary Circulation
 Functional blood supply to heart muscle itself
 Delivered when heart relaxed
 Left ventricle receives most blood supply
 Arterial supply varies among individuals
 Contains many anastomoses (junctions)
 Provide additional routes for blood delivery
 Cannot compensate for coronary artery occlusion
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Coronary Circulation:
Arteries
Arteries arise from base of aorta
Left coronary artery branches 
anterior interventricular artery and
circumflex artery
 Supplies interventricular septum,
anterior ventricular walls, left atrium,
and posterior wall of left ventricle
Right coronary artery branches 
right marginal artery and posterior
interventricular artery
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Aorta
Pulmonary
trunk
Left atrium
Superior
vena cava
Anastomosis
(junction of
vessels)
Left
coronary
artery
Right
atrium
Right
coronary
artery
Right
ventricle
Right
marginal
artery
Circumflex
artery
Posterior
interventricular
artery
The major coronary arteries
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Left
ventricle
Anterior
interventricular
artery
Coronary Circulation: Veins
Cardiac veins collect blood from
capillary beds
Coronary sinus empties into right
atrium; formed by merging cardiac
veins
 Great cardiac vein of anterior
interventricular sulcus
 Middle cardiac vein in posterior
interventricular sulcus
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Education,cardiac
Inc.
 Small
vein from inferior margin
Superior
vena cava
Anterior
cardiac
veins
Great
cardiac
vein
Coronary
sinus
Small
cardiac vein
The major cardiac veins
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Middle cardiac vein
Aorta
Superior vena cava
Left pulmonary artery
Right pulmonary artery
Right pulmonary veins
Left pulmonary veins
Auricle of left atrium
Left atrium
Great cardiac vein
Posterior vein of
left ventricle
Left ventricle
Apex
Posterior surface view
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Right atrium
Inferior vena cava
Coronary sinus
Right coronary artery
(in coronary sulcus)
Posterior interventricular
artery (in posterior
interventricular sulcus)
Middle cardiac vein
Right ventricle
Homeostatic Imbalances
 Angina pectoris
 Thoracic pain caused by fleeting deficiency in blood
delivery to myocardium
 Cells weakened
 Myocardial infarction (heart attack)
 Prolonged coronary blockage
 Areas of cell death repaired with noncontractile scar
tissue
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Figure 18.12a Microscopic anatomy of cardiac muscle.
Nucleus
Intercalated
discs
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Cardiac
muscle cell
Gap junctions
Desmosomes
Microscopic Anatomy of
Cardiac Muscle
 Intercalated discs - junctions between cells anchor cardiac cells
 Desmosomes prevent cells from separating during
contraction
 Gap junctions allow ions to pass from cell to cell;
electrically couple adjacent cells
 Allows heart to be functional syncytium
 Behaves as single coordinated unit
© 2013 Pearson Education, Inc.
Figure 18.12b Microscopic anatomy of cardiac muscle.
Cardiac muscle
cell
Intercalated
disc
Mitochondrion Nucleus
Mitochondrion
T tubule
Sarcoplasmic
reticulum
Z disc
Nucleus
Sarcolemma
I band
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A band
I band