How is cardiac muscle similar to a smooth muscle

Smooth muscles and cardiac muscles are both classified as involuntary. Both muscles are continuously working which means it does not stop even when a person is at rest.  As smooth muscles surround most of the walls of the major organs of the body, cardiac muscle however can only be found in the heart. They are not both innervated singularly which implies that the impulses that travels through these paths are passed from a cell to another cell. Both are automatically controlled by endocrine and nervous systems and produce rhythmic contractions as impulses are innervated. 

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