HUMAN ANATOMY AND PHYSIOLOGY

 MUSCULAR TISSUE

It is the type of excitable tissue possessing contractile ability it is of three types (1) skeletal (2) visceral (3)cardiac 

skeletal muscles :: 

skeletal muscles are usually attached to bones (and hence known as skeletal) they are under the control of will and so they are known as voluntary muscles fibres of skeletal muscle are long cylindrical shaped and showing distinct striations ( hence also known as striated fibres) each fibre is surrounded by a thin membrane sarcolemma each fibre consists of a number of nuclei the myofibrils are embedded in the sarcoplasm fibres are unbranched 

visceral muscles::

it is the type of muscular tissue found in visceral organs (hence known as visceral muscles ) they are under the control of autonomic nervous system and are involuntary in nature 
each fibres is long spindle shaped with single centrally placed nucleus they are unbranched the striations are not seen (hence known as smooth muscles ) the nucleus is surrounded by small amount of cytoplasm sarcoplasm and the fibres are not surrounded any membrance but several of them are joined together by loose connective tissue

cardiac muscles::

it is the type of muscular tissue found in heart (and hence known as cardiac muscle) they are also not under the control of will and hence are involuntary in nature 
fibres are long and cylindrical but are branched branches join with each other fibres ultimately forming three dimensional net work each fibres is surrounded by sarcolemma and has longitudinal myofibrils at regular intervals there are thick dark intercalated discs which represent the cell membranes of adjacent cardiac muscle cells each muscle cell has a distinct nucleus   

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