Transcript Chapter 18 The Cardiovascular System

CH 18:
Gross Anatomy of the Heart
J.F. Thompson, Ph.D.
Located in the Ventral Body Cavity
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Ventral body cavity
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thoracic
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pleural
pericardial
mediastinum
abdominopelvic
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abdominal
pelvic
The Size of the Heart
• About same size as a
closed fist
• the base is the wider
superior portion
• the apex is the point
Pericardium
The sac containing the heart
Fibrous Pericardium
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rests on and is attached
to diaphragm
a tough, inelastic sac of
fibrous connective tissue
anchored to the blood
vessels entering and
leaving the base of the
heart
protects and anchors the
heart; prevents
overfilling of the
chambers of the heart
Parietal (Outer) Serous Pericardium
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simple squamous
epithelium
forms outer parietal
layer bound to
fibrous pericardium
secretes a serous
(watery) lubricating
fluid
reduces friction as
the heart contracts
and twists
Visceral (Inner) Serous Pericardium
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simple squamous
epithelium forms
the epicardium
forms visceral
layer bound to the
myocardium of the
heart
secretes serous
fluid
reduces friction as
the heart pumps,
contracts and
twists
Heart wall - Three layers
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Epicardium (outer)
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Myocardium (middle)
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visceral layer of
pericardium
thin, transparent
smooth, slippery
mass of cardiac muscle
Endocardium (inner)
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endothelium over thin
connective tissue
smooth lining for the
chambers and valves
continuous with blood
vessel endothelium
Myocardium (Cardiac Muscle)
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Cardiac muscle cells are
involuntary, striated,
branched
Each fiber is connected
to the others by
intercalated discs
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gap junctions allow
action potentials to pass
from fiber to fiber
desmosomes (“spot
welds”) to prevent
cardiac fibers from
separating during
contractions
Intercalated Discs
[Note the striations and
recall the sliding filament
method of muscle
contraction.]
Surface of the Heart
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External
landmarks
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Atrioventricular
grooves separate
atria from
ventricles
Anterior/posterior
interventricular
sulcus separates
right and left
ventricles
Coronary vessels
run in these
grooves
End
Anatomy of the Heart
CH 18