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8/2/2019 Muscle Histology by Dr Roomi
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MUSCULAR TISSUE
BY
DR. MUDASSAR ALI ROOMI (MBBS, M. PHIL)
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MUSCULAR TISSUE
•
One of the four basic tissues of body• Cells of muscular tissue are elongated = fibers
• Muscle fibers have the property of contractility.
• Sarcolemma= cell membrane of muscle fibers.
• Sarcoplasm= cytoplasm of the muscle fibers
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CLASSIFICATION OF THE MUSCULAR TISSUE
• Non-striated muscle (smooth muscle)
• Striated muscle (cardiac, skeletal muscle)
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SMOOTH MUSCLE
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SMOOTH MUSCLE
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SMOOTH MUSCLE
• No cross striations
• Location: in the walls of
blood vessels, hollowviscera
• Function: controls the
size of the lumen.
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SMOOTH MUSCLE
• Shape: each fiber is
fusiform in shape.
• Diameter: 3-8 um
• Length: 15-200 um
• Nucleus: single, rod-
shaped nucleus located
in the centre of eachcell.
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Cytoplasm of smooth muscle fiber
• E/M shows that actin andmyosin are present in thecytoplasm.
• Actin: diamter is 5-7 nm
•
Myosin: diameter 12-16 nm• actin/myosin ratio: 15/1
• Desmin intermediatefilaments are also present inthe cytoplasm. (dia= 10 nm)
•Dense bodies: intermediatefilaments cross over oneanother to form darklystaining patches.
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MULTI-UNIT AND UNITARY
SMOOTH MUSCLES
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MULTI-UNIT AND UNITARY SMOOTH MUSCLES
• LOCATION
• TYPE OF JUNCTIONS
•
ARRANGEMENT• CONTROL
• ACTION POTENTIAL.
•
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MULTI-UNIT AND UNITARY SMOOTH MUSCLES
1: LOCATION:
• UNITARY: Wall of GIT,
ureter, bile duct, uterus and
large blood vessels.
• MULTIUNIT: Ciliary muscle
of eye, Iris of eye and pilo-erector muscle.
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MULTI-UNIT AND UNITARY SMOOTH MUSCLES
2: ARRANGEMENT:
• UNITARY: Sheaths or
bundles with gap junctionsin between, so act as single
unit. If one part is excited
whole is excited.
• MULTIUNIT: Individual
muscle fibers. Each fiber has
insulating outer membranewith glycoprotein and
collagen consistency.
Independently each muscle
fiber is excited.
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MULTI-UNIT AND UNITARY SMOOTH MUSCLES
3: TYPE OF JUNCTION:
• UNITARY: Diffuse
junction. No contact
with nerve fiber.Neurotransmitter is
released near the fiber.
• .
• MULTIUNIT: Contact
junction.One of the
autonomic nerves form junction with muscle
fiber and releases
neurotransmitter like
nor-epinephrine
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MULTI-UNIT AND UNITARY SMOOTH MUSCLES
4: CONTROL:
• UNITARY: Mainly non-
nervous stimuli
(hormonal stimuli likeoxytocin and serotonin).
Show spontaneous
contraction.
• MULTIUNIT: Mainly
through nervous
stimuli. Does not show
spontaneouscontraction
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MULTI-UNIT AND UNITARY SMOOTH MUSCLES
5: ACTION POTENTIAL:
• UNITARY: 3 types:
Spike, Plateau and Slow
wave.
• MULTIUNIT: Not
required as individual
muscle fibers are too
small to produce actionpotential. Only localized
depolarization in
response to excitation.
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MULTI-UNIT AND UNITARY SMOOTH MUSCLES
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Skeletal muscle
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Cardiac muscle
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