Muscle Histology by Dr Roomi

8/2/2019 Muscle Histology by Dr Roomi

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MUSCULAR TISSUE

BY

DR. MUDASSAR ALI ROOMI (MBBS, M. PHIL)



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



CLASSIFICATION OF THE MUSCULAR TISSUE

• Non-striated muscle (smooth muscle)

• Striated muscle (cardiac, skeletal muscle)



SMOOTH MUSCLE



SMOOTH MUSCLE



SMOOTH MUSCLE

• No cross striations

• Location: in the walls of

blood vessels, hollowviscera

• Function: controls the

size of the lumen.



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.



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.





MULTI-UNIT AND UNITARY

SMOOTH MUSCLES



MULTI-UNIT AND UNITARY SMOOTH MUSCLES

• LOCATION

• TYPE OF JUNCTIONS

•

ARRANGEMENT• CONTROL

• ACTION POTENTIAL.

•




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.




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.




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




4: CONTROL:

• UNITARY: Mainly non-

nervous stimuli

(hormonal stimuli likeoxytocin and serotonin).

Show spontaneous

contraction.

• MULTIUNIT: Mainly

through nervous

stimuli. Does not show

spontaneouscontraction




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.






Skeletal muscle



Cardiac muscle



Muscle Histology by Dr Roomi

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