Muscles

The various movements of our body take place with the help of muscles.

Muscles cover theskeletal framework of the body and are responsible for providing shape or contour to the body. Muscles show excitability, contractility, extensibility and elasticity.Muscles are long bundles of contractile tissues.

Muscles are attached to bones by tendons, which are made up of white fibrous connective tissue.

Biceps muscles are two bundles of muscle with two separate heads or points of origin.These muscles help in pulling and lifting movements.

Triceps muscles are three bundles of muscle with three separate heads or points of origin.

Rotation is the movement of a body part in such a way that it forms a cone. Supination is the rotation of forearm, so that palm faces anteriorly while pronation is the rotation of forearm, so that palm faces posteriorly.

Inversion is the inward movement of sole of foot while eversion is the outward movement of sole of foot.

Muscles occur in antagonistic pairs, which cause opposing movements. Muscles can be voluntary or involuntary.

Muscles have to be coordinated for a particular type of movement. Combined action of various muscles bring about different movements like standing, walking, running and playing etc. In producing body movements, bones act as lever and joints act as fulcrums of these levers

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  • Q1

    A large number of parallely arranged filaments are found in muscle fibre and are called

    Marks:1
    Answer:

    myofibril.

    Explanation:
    A characteristic feature of the muscle fibre is the presence of a large number of parallely arranged filaments in the sarcoplasm called myofilaments or myofibrils that consist of actin and myosin proteins.
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  • Q2

    The reduction in the size of individual muscle cells is called

    Marks:1
    Answer:

    atrophy.

    Explanation:
    Atrophy is a continuous decline of a body part or tissue, usually a muscle, following a period of disuse or immobility.
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  • Q3

    If the nerve supply alone is cut off from a muscle, it causes

    Marks:1
    Answer:

    denervation atrophy.

    Explanation:
    Denervation atrophy is a progressive shrinkage of muscle fibers when the nerve supply to the muscle is severed.
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  • Q4

    Heart beat conduction is controlled by a nodal tissue which is made up of specialised cardiac muscles, called

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    Answer:

    purkinje fibres.

    Explanation:
    Purkinje fibres are located in the inner ventricular walls of the heart, just beneath the endocardium. These fibers are specialized myocardial fibers that conduct an electrical stimulus or impulse that enables the heart to contract in a coordinated fashion.
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  • Q5

    The viral disease that weakens the muscles is

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    Answer:

    poliomyletis.

    Explanation:
    Poliomyletis is a viral paralytic disease. The causative agent, a virus called poliovirus, enters the body orally, infecting the intestinal lining. It may proceed to the blood stream and into the central nervous system causing paralysis and muscle weakness.
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