Answer:
The striated muscle fibres are long or
elongated, non-tapering and cylindrical and unbranched. These cells have a
number of nuclei called sarcolemma. These muscle fibres shows alternate dark
and light stripes or striations and they are called striated muscles and
finally to the brain or spinal cord. Striated muscles occur in muscles of
limbs, body wall, face, neck, etc.
Functions of striated muscles:
(i) Striated muscles are
powerful and undergo rapid contraction.
(ii) Striated muscles provide
the force for locomotion and all other voluntary movements of the body.
These muscles are also known as
unstriated or involuntary muscles. Smooth muscles occur as bundles or sheets of
elongated fusiform or spindle-shaped cells or fibres. They are held together by
loose connective tissue. These muscle fibres are uninucleate and do not bear
any bands, stripes or striation across them and hence, they are called smooth
or unstriated muscles. These muscles are found in the walls of the alimentary
canal and internal organs, ducts of glands and blood vessels. Smooth muscles
are also found in the stomach, intestine, ureters, bronchi, iris of the eye,
etc.
Functions of smooth muscles:
(i) Smooth muscles do not work
according to our will, so they are also called involuntary muscles. Movement of
food in the alimentary canal or the contraction and relaxation of blood vessels
are involuntary movements.
(ii) Smooth muscles contract
slowly but can remain contracted for a long period of time. Due to this
characteristic, the food passes to the next step of digestion in the alimentary
canal.
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