7- muscular tissue
Post on 31-Mar-2016
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MUSCULAR TISSUES
There are types of muscles:-
- Skeletal muscles fibers.
- Cardiac muscles fibers.
- Smooth muscle fibers.
Skeletal muscles
- They are striated and voluntary muscles.
- Under the microscope, the cells show
transverse dark and light bands.
- They are attached to the skeleton, so, their
contraction move the skeleton.
- Sk. M. formed of elongated cells (muscle fibers)
and connective tissue in between.
- Loose CT arranged around and in between
muscles fibers and bundles.
- CT carries blood vessels, lymphatics, and
nerve fiber to muscle.
The connective tissue component
- The connective tissues are arranged as:-
- Epimysium: the outer coat of the muscle.
- Perimysium: around the muscle bundles and fascicles.
- Endomysium: between each muscle fiber.
The connective tissue component
Skeletal muscle fiber
- The muscle fiber is long and cylindrical in
shape.
- The nuclei are multiple, long and
peripheral.
- The cytoplasm show alternative dark and light
striations.
- The dark band is called anisotropic or
A- band.
- The light band is called isotropic or
I - band.
- In the middle of the dark A band there is
a pale region called H-zone.
- In the middle of the light band there is a
dark line called Z- line.
- The distance between two successive Z lines
is called Sarcomere.
- Sarcomere is the functional unit for muscle
contraction.
Myofibrils
- The cytoplasm or sarcoplasm is full of parallel
myofibrils, which are formed of two types of
fine myofilaments:-
- Thick myosin filaments in the A-bands.
- Thin actin filaments in the both I & A
bands.
-The arrangements of actin and myosin filaments
give the myofibrils their striation.
Motor unit: group of muscle fibers innervated by
collection of individual nerve branches within
muscle.
Neuromuscular junction: required for growth and
determines type of metabolism (red or white
fibers) by frequency of impulses,
any one motor nerve supplies fibers of one type
only; all fibers of particular motor unit are of
same metabolic type.
Neuromuscular junction (motor end plate):
contains concentration of mitochondria and rER
Cardiac muscle
- Cardiac muscle is striated involuntary muscle.
- The sarcoplasm containing a single, oval,
prominent and central nucleus.
- The muscle fibers are shorter than skeletal
muscle fibers and branched.
- The short cardiac muscle fibers are joined
together by intercalated discs.
- These discs appear as dark lines.
Smooth muscles
- Visceral involuntary muscle fibers.
- It is smooth because there are no striation.
- The cytoplasm is full of actin and myosin filament.
- The cytoplasm is acidophilic with central and single nucleus.
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