REVIEW CONCEPTS:
Chapter 19
The Heart and Cardiovascular Function
Structure of the Heart
o Describe the heart’s location, shape, and borders.
o Describe the structure of the pericardium and explain its
functions, identify the layers of the heart wall, and describe the
structures and functions of cardiac muscle.
o Describe the location and general features of the heart.
o Describe the cardiac chambers and the heart’s external anatomy.
o Describe the major vessels supplying the heart, and cite their
locations.
Trace blood flow through the heart, identifying the major blood vessels,
chambers, and heart valves.
o Describe the relationship between the AV and semilunar valves during
a heartbeat.
o Define arteriosclerosis, and explain its significance to health.
Orientation to the Heart
Base and apex
o Base
Superior surface of the heart
Great veins and arteries attach here
Posterior to the sternum at the third costal cartilage
Centered 1.2 cm (0.5 in.) to the left
o Apex
Inferior, pointed tip of the heart
Reaches the fifth intercostal space
About 7.5 cm (3 in.) to the left of midline
~12.5 cm (5 in.) from base to apex
o Superior border
Formed by the base
o Right border
Formed by the right atrium
o Left border
Formed by the left ventricle and a small part of left atrium
o Inferior border
Formed mainly by the inferior wall of the right ventricle
Heart Wall and Tissues
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,Layers of the heart wall
1. Epicardium (visceral pericardium)
Covers the outer surface of the heart
Serous membrane made of exposed mesothelium and
underlying areolar tissue (attached to the myocardium)
)
2. Myocardium
Middle, muscular layer forming atria and ventricles
Contains cardiac muscle tissue, blood vessels, and nerves
Composed of concentric muscle tissue layers
Atrial myocardium
o Muscle bundles wrap around atria
o Form figure-eights encircling large arteries and veins at
the base of the heart
Ventricular myocardium
o Superficial muscle layers wrap both ventricles
o Deeper muscle layers spiral around and between
ventricles toward apex in a figure-eight pattern
3. Endocardium
Covers inner surfaces of heart, including valves
Composed of simple squamous epithelial tissue and underlying
areolar tissue
o Epithelial portion is called endothelium
o Cardiac endothelium is continuous with endothelium of
attached great vessels
The pericardium
o Serous membrane that lines the pericardial cavity and covers the heart
1. Visceral pericardium (also referred to as the epicardium)
attached to the heart
2. Parietal pericardium (lining the outer wall of the pericardial
cavity)
o Reinforced by a dense fibrous layer
Pericardial sac
o Formed by parietal pericardium and the dense fibrous
layer
o Surrounds the heart
Cardiac muscle tissue
o Compared to skeletal muscle tissue
1. Smaller cell size
o 10–20 μm in diameter; 50–100 μm in length
2. Single, centrally located nucleus
3. Branching interconnections between cells
4. Specialized intercellular connections
o Intercalated discs
Cardiac muscle tissue (continued)
o Found only in the heart
© 2015 Pearson Education, Inc.
, o Cells contain organized myofibrils
o Arrangement of filaments in sarcomeres gives striated appearance
o Almost totally dependent on aerobic (need oxygen) metabolism for
energy
Large numbers of mitochondria and myoglobin to store O2
Has large number of capillaries to supply nutrients and O2
Cardiac muscle tissue (continued)
o Intercalated discs
Where plasma membranes of adjacent cardiac muscle cells
intertwine
Bound together by desmosomes and gap junctions
Allow entire tissue to “pull together” as one enormous muscle
cell
o Cardiac muscle called a functional syncytium (fused
mass of cells)
Cardiac muscle tissue (continued)
o Intercalated discs (continued)
Desmosomes
o Anchor adjacent cells together
o Stabilize positions of adjacent cells
Gap junctions
o Allow ions and molecules to move directly between cells
o Create direct electrical connection so an action potential
can pass directly between cells
The Pericardial Cavity
Mediastinum
o Region between the two pleural (lung) cavities
o Heart found in the anterior portion
Surrounded by the pericardial sac
o Also contains:
Great vessels (entering and exiting the heart)
Thymus
Esophagus
Trachea
Pericardium analogy
o A fist pushed into a partially inflated balloon
Fist = heart
Wrist = base of the heart where great vessels attach
Air space in the balloon = pericardial cavity
Inner wall of balloon = visceral pericardium
Outer wall of balloon = parietal pericardium
Pericardial sac or fibrous pericardium
o Surrounds the heart
o Composed of dense network of collagen fibers
© 2015 Pearson Education, Inc.
Chapter 19
The Heart and Cardiovascular Function
Structure of the Heart
o Describe the heart’s location, shape, and borders.
o Describe the structure of the pericardium and explain its
functions, identify the layers of the heart wall, and describe the
structures and functions of cardiac muscle.
o Describe the location and general features of the heart.
o Describe the cardiac chambers and the heart’s external anatomy.
o Describe the major vessels supplying the heart, and cite their
locations.
Trace blood flow through the heart, identifying the major blood vessels,
chambers, and heart valves.
o Describe the relationship between the AV and semilunar valves during
a heartbeat.
o Define arteriosclerosis, and explain its significance to health.
Orientation to the Heart
Base and apex
o Base
Superior surface of the heart
Great veins and arteries attach here
Posterior to the sternum at the third costal cartilage
Centered 1.2 cm (0.5 in.) to the left
o Apex
Inferior, pointed tip of the heart
Reaches the fifth intercostal space
About 7.5 cm (3 in.) to the left of midline
~12.5 cm (5 in.) from base to apex
o Superior border
Formed by the base
o Right border
Formed by the right atrium
o Left border
Formed by the left ventricle and a small part of left atrium
o Inferior border
Formed mainly by the inferior wall of the right ventricle
Heart Wall and Tissues
© 2015 Pearson Education, Inc.
,Layers of the heart wall
1. Epicardium (visceral pericardium)
Covers the outer surface of the heart
Serous membrane made of exposed mesothelium and
underlying areolar tissue (attached to the myocardium)
)
2. Myocardium
Middle, muscular layer forming atria and ventricles
Contains cardiac muscle tissue, blood vessels, and nerves
Composed of concentric muscle tissue layers
Atrial myocardium
o Muscle bundles wrap around atria
o Form figure-eights encircling large arteries and veins at
the base of the heart
Ventricular myocardium
o Superficial muscle layers wrap both ventricles
o Deeper muscle layers spiral around and between
ventricles toward apex in a figure-eight pattern
3. Endocardium
Covers inner surfaces of heart, including valves
Composed of simple squamous epithelial tissue and underlying
areolar tissue
o Epithelial portion is called endothelium
o Cardiac endothelium is continuous with endothelium of
attached great vessels
The pericardium
o Serous membrane that lines the pericardial cavity and covers the heart
1. Visceral pericardium (also referred to as the epicardium)
attached to the heart
2. Parietal pericardium (lining the outer wall of the pericardial
cavity)
o Reinforced by a dense fibrous layer
Pericardial sac
o Formed by parietal pericardium and the dense fibrous
layer
o Surrounds the heart
Cardiac muscle tissue
o Compared to skeletal muscle tissue
1. Smaller cell size
o 10–20 μm in diameter; 50–100 μm in length
2. Single, centrally located nucleus
3. Branching interconnections between cells
4. Specialized intercellular connections
o Intercalated discs
Cardiac muscle tissue (continued)
o Found only in the heart
© 2015 Pearson Education, Inc.
, o Cells contain organized myofibrils
o Arrangement of filaments in sarcomeres gives striated appearance
o Almost totally dependent on aerobic (need oxygen) metabolism for
energy
Large numbers of mitochondria and myoglobin to store O2
Has large number of capillaries to supply nutrients and O2
Cardiac muscle tissue (continued)
o Intercalated discs
Where plasma membranes of adjacent cardiac muscle cells
intertwine
Bound together by desmosomes and gap junctions
Allow entire tissue to “pull together” as one enormous muscle
cell
o Cardiac muscle called a functional syncytium (fused
mass of cells)
Cardiac muscle tissue (continued)
o Intercalated discs (continued)
Desmosomes
o Anchor adjacent cells together
o Stabilize positions of adjacent cells
Gap junctions
o Allow ions and molecules to move directly between cells
o Create direct electrical connection so an action potential
can pass directly between cells
The Pericardial Cavity
Mediastinum
o Region between the two pleural (lung) cavities
o Heart found in the anterior portion
Surrounded by the pericardial sac
o Also contains:
Great vessels (entering and exiting the heart)
Thymus
Esophagus
Trachea
Pericardium analogy
o A fist pushed into a partially inflated balloon
Fist = heart
Wrist = base of the heart where great vessels attach
Air space in the balloon = pericardial cavity
Inner wall of balloon = visceral pericardium
Outer wall of balloon = parietal pericardium
Pericardial sac or fibrous pericardium
o Surrounds the heart
o Composed of dense network of collagen fibers
© 2015 Pearson Education, Inc.
