Download aponeurosis

Review:
Fig. 7.1
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Functions of Skeletal Muscle:
 Support the body (opposes the force
of gravity)
 Make bones and other body parts
move
 Maintain a constant body temperature
 Assist movement in cardiovascular
and lymphatic vessels
 Protect internal organs and stabilize
joints
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Microscopic Anatomy of Skeletal
Muscle:
 What do we already know from
histology? Striations.
 Arrangement of myofilaments in a
muscle fiber (cell).
 Normal cell with some specialized
terms for cell parts. (Plasma membrane = sarcolema,
endoplasmic reticulum = sarcoplasmic reticulum)
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Microscopic Anatomy of Muscle
(Sarcoplasmic Reticulum)
 Remember this is the ER for muscle
cells.
 Sarcoplasmic reticulum has
specialized pockets to store calcium
ions (Ca2+) which is essential for
muscle contraction.
 The sarcoplasmic reticulum encases
hundreds of myofibrils which allow for
contraction of the muscle cell.
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Microscopic Anatomy of Muscle:
 Myofibrils run the length of the
muscle fiber.
 Striations are formed by the
placement of these myofibrils forming
sarcomeres.
 Sarcomeres contain two types of
protein fibers: actin (thin and
intertwined) and myosin (thick and
shaped like golf club).
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Fig. 7.3a
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Fig. 7.3b
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Microscopic Anatomy of Muscle:
 Sliding Filaments – when the muscles are
triggered by motor nerve cells, impulses
travel down the T-tubule of the sarcomere
(see previous picture).
Calcium is then released from the
sarcoplasmic reticulum. This causes the
sarcomere to shorten. The actin slides
across the myosin. ATP provides the power
for this contraction.
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Fig. 7.4
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Fig. 7.5
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Macroscopic Anatomy of Muscle:
 3 Layers of connective tissue are part of
each muscle:
Epimysium – surrounds entire muscle,
dense layer of collagen fibers.
Perimysium – divides muscle into
compartments called fascicles.
Endomysium – delicate connective tissue
that surrounds each muscle cell or fiber.
 Where these connective tissues run
together at the end of muscles they form
tendons or aponeurosis.
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Fig. 7.2a
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