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Muscle tissue
Lecture objectives
 describe the major structural and functional differences
among the three types of muscle tissue
 compare skeletal and smooth muscle cells with respect
to organelles, cytoskeleton, and contractile filaments.
 compare and contrast differences in cardiac and
skeletal muscle cell structure
 discuss the connection between the sarcolemma and the
Transverse tubules.
 describe the makeup of sarcoplasm.
 explain how the arrangement of the myofilaments form
the observed sarcomere structural patterns
Dr Ibrahim
Slide 1 of
Muscular Tissue
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Consists of elongated cells called muscle
fibers or myocytes
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Cells use ATP to generate force
Several functions of muscle tissue
Classified into 3 types: skeletal, cardiac, and
smooth muscular tissue
Dr Ibrahim
Slide 2 of
Skeletal Muscle Tissue
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2/5/2010
Attached to bones of the skeleton
Have striations
Voluntary movement or contractions by conscious control
Vary in length (up to 40 cm) and are roughly cylindrical in
shape
Dr Ibrahim
Slide 3of
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Outer epimysium CT
Perimysium around
bundles
Endomysium
surround fibre (cell)
Cell has contractile
proteins (myofibrils)
multinucleated
Slide 4of
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Cell membrane
(sarcolemma)
Transverse tubules
Rich in Endoplasmic
reticulum
(sarcoplasmic
reticulum)
Slide 5 of
Triad
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Triad (3 things)
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2 sarcoplasmic reticula
1 T-tubule
For excitationcontraction coupling
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Band pattern
Electronmicrograph of muscle fibre
Dr Ibrahim
Slide 7 of
myoproteins
 Actin and myosin
 others
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2/5/2010
actinin
titin
desmin
myomesin
dystrophin
Slide 8 of
Skeletal Muscle Tissue
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Contractile Proteins
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Myosin
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Thick filaments
Functions as a motor protein which can achieve motion
Convert ATP to energy of motion
Projections of each myosin molecule protrude outward (myosin
head)
Dr Ibrahim
Slide 9 of
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Actin
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2/5/2010
Thin filaments
Tropomyosin and troponin are also part of the thin filament
In relaxed muscle
Myosin is blocked from binding to actin
Calcium ion binding to troponin moves tropomyosin away from
myosin-binding sites
Allows muscle contraction to begin as myosin binds to actin
Dr Ibrahim
Slide 10 of
Skeletal Muscle Tissue
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Structural Proteins
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Titin
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Stabilize the position of myosin
accounts for much of the elasticity and extensibility of
myofibrils
Dystrophin
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Links thin filaments to the sarcolemma
Dr Ibrahim
Slide 11 of
Dr Ibrahim
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Muscular Tissue
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Cardiac muscle tissue
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2/5/2010
Have striations
Involuntary movement or contraction is not consciously
controlled
Intercalated disc unique to cardiac muscle tissue
Dr Ibrahim
Slide 13of
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Cells show branching
Rich in sarcoplasmic
reticulum
Single nucleus
Rich in mitochondria
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Why?
Slide 14of
Intercalated discs
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Int. disc contain
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Desmosomes
Gap junctions
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Why?
Slide 15 of
Compare
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Smooth Muscle Tissue
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Walls of hollow internal structures
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Blood vessels, airways of lungs, stomach, and intestines
Nonstriated
Usually involuntary control
Dr Ibrahim
Slide 17of
Smooth muscle
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spindle-shaped fibers.
Lack perimysium but have
endomysium.
Generally organized into two
layers (longitudinal and circular).
Found in walls of hollow organs
(except the heart).
the same contractile mechanisms
as skeletal muscle
Single nucleus
Slide 18of
Types of smooth muscle
single-unit smooth muscle
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Contract rhythmically as a unit (packed closely)
Are electrically coupled to one another via gap
junctions.
Multi-unit smooth muscle
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Have spaces between them
Contract independently
Dr Ibrahim
Slide 19 of