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| Cardiac Muscle |
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| It is also known as heart muscle. |
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| The cardiac muscle fibres do not form fasciles. They are arranged in the form of a network. The muscle fibres are elongated, cylindrical and branched. The branches become inter-connected with one another to form a network. The space between the muscle fibres is filled with connective tissue. Each muscle fibre has a thin and indistinct sarcolemma. It encloses abundant sarcoplasm. The muscle fibres are multinucleate. The nuclei are situated away from the sarcolemma. The nuclei are separated from one another due to the presence of numerous horizontal plate like structures called intercalated discs. Myofibrils are present forming faint striations resembling a mesh work. |
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| fig 5.59 Cardiac Muscle |
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| The cardiac muscle fibres have a very rich supply of blood. They are supplied with sympathetic and parasympathetic nerves from the autonomic nervous system. The contractions are slow but highly rhythmic and not sustained. The muscle never experiences fatigue. It is described as involuntary since its functioning is not under the control of our will. |
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| Cardiac muscle occurs exclusively in the heart. |
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