Muscular tissue is composed of Muscle cells. Muscle cells show three essential properties such as excitability, conductivity and contractility. Muscle cells are in enlongated form of fibres (Myocytes). The myocytes have several Myofibrils which are responsible for the alternate dark and light bands on striated or striped muscle. A skeletal muscle is made up of striped muscle cells. Each skeletal muscle fibre is long cylindrical and unbranched cell. It is a multinucleated cell with many oval nuclei. These cells work under conscious control of an organism.
Draw two parallel curves and mark several dark bands at uniform distance as shown.
Make oval nuclei here are there and label.
Smooth muscle is located in the walls of the visceral organs such as blood vessels, trachea, bronchi, stomach, intestine, excretory and genital ducts etc. These muscle cells are also present in Iris and ciliary body of eye and in the skin as arrector pili that are attached to hair follicles. Usually these cells are arranged in the form of sheets. A smooth muscle fibre is spindle shaped, uninucleate. Myofibrils do not show alternate dark and light bands due to irregular arrangement of actin and myosin molecules. They do not work under conscious control. They can remain in contracted state for long period without fatigue. They are under the control of Autonomous nervous system.
Draw a spindle shape and make several curves which represent Myofibrils. Draw a single round nucleus at center.
Cardiac muscle is striated like the skeletal muscle. It is found in the Myocardium of the heart of vertibrates. These cells are short cylindrical, mononucleate or binucleate cells, whose ends branch and form junctions with other cardiac muscle cells. The Dark lines across cardiac muscle cells are called Intercalated discs.
Draw four or five rows of striped muscle cells and connect them randomly through branches.
Draw Intercalated discs and mark several bands.
Finally draw nuclei as shown.
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