Q. Skeletal muscles show resemblance with visceral muscles in one aspect. It is in the
Solution:
(1) Striated muscle:
Location: The striated muscle is normally found attached to the bones in the head, trunk and limbs. Hence, it is called skeletal muscle. It is also found in the body wall, tongue, pharynx and at the beginning of the oesophagus. In a vertebrate body, it forms more than 80% of the soft tissues.
Structure:
(i) A number of muscle fibres run parallel to each other and are arranged in bundles called fasciculi. The fascicule is bound together by connective tissue.
(ii) Each muscle fibre is about 40 mm in length.
(iii) Each muscle fibre is bound by an elastic membrane called sarcolemma.
(iv) The sarcoplasm also contains a network of endoplasmic reticulum called sarcoplasmic reticulum.
(v) Each muscle fibre is made up of numerous myofibrils.
(vi) Each myofibril shows alternate dark and light crossbands, the striations or strips. Hence, the name striated or striped muscle.
(vii) Striated muscle fibres can contract quickly. They undergo fatigue easily. So they are also called fatigue muscle.
(viii) The striated muscles can be moved according to the will of the animal. So they are also called voluntary muscles.
(2) Non-striated muscle/Visceral muscle:
Location: They are found in walls of visceral organs like alimentary canal, genital and urinary ducts, blood vessels and urinary bladder muscles. They are also found in the dermis of skin, iris and ciliary body of the eye.
Structure:
(i) Each muscle fibre is long, narrow and spindle-shaped with tapering ends.
(ii) Each muscle fibre maybe 0.02 to 0.05 mm in length and 5 to 10 µm in diameter. It is generally shorter than striated muscle fibre.
(iii) Myofibril is made up of actin & myosin but remarkably less than skeletal muscle but filaments are not placed in a highly ordered pattern so striation is absent. Actin is more than myosin
(iv) The non-striated muscles cannot be moved on one’s own will, they are involuntary.
(v) The non-striated muscles contract and relax slowly. They can remain contracted for a long time without getting fatigued.
Location: The striated muscle is normally found attached to the bones in the head, trunk and limbs. Hence, it is called skeletal muscle. It is also found in the body wall, tongue, pharynx and at the beginning of the oesophagus. In a vertebrate body, it forms more than 80% of the soft tissues.
Structure:
(i) A number of muscle fibres run parallel to each other and are arranged in bundles called fasciculi. The fascicule is bound together by connective tissue.
(ii) Each muscle fibre is about 40 mm in length.
(iii) Each muscle fibre is bound by an elastic membrane called sarcolemma.
(iv) The sarcoplasm also contains a network of endoplasmic reticulum called sarcoplasmic reticulum.
(v) Each muscle fibre is made up of numerous myofibrils.
(vi) Each myofibril shows alternate dark and light crossbands, the striations or strips. Hence, the name striated or striped muscle.
(vii) Striated muscle fibres can contract quickly. They undergo fatigue easily. So they are also called fatigue muscle.
(viii) The striated muscles can be moved according to the will of the animal. So they are also called voluntary muscles.
Location: They are found in walls of visceral organs like alimentary canal, genital and urinary ducts, blood vessels and urinary bladder muscles. They are also found in the dermis of skin, iris and ciliary body of the eye.
Structure:
(i) Each muscle fibre is long, narrow and spindle-shaped with tapering ends.
(ii) Each muscle fibre maybe 0.02 to 0.05 mm in length and 5 to 10 µm in diameter. It is generally shorter than striated muscle fibre.
(iii) Myofibril is made up of actin & myosin but remarkably less than skeletal muscle but filaments are not placed in a highly ordered pattern so striation is absent. Actin is more than myosin
(iv) The non-striated muscles cannot be moved on one’s own will, they are involuntary.
(v) The non-striated muscles contract and relax slowly. They can remain contracted for a long time without getting fatigued.