This group of cells is self-excitable and able to depolarize to threshold and fire action potentials on their own, a feature called autorhythmicity ; they do this at set intervals which determine heart rate. Cardiac muscle is striated muscle that is present only in the heart.
Cardiac muscle fibers have a single nucleus, are branched, and joined to one another by intercalated discs that contain gap junctions for depolarization between cells and desmosomes to hold the fibers together when the heart contracts.
Pacemaker cells stimulate the spontaneous contraction of cardiac muscle as a functional unit, called a syncytium. What would be the drawback of cardiac contractions being the same duration as skeletal muscle contractions?
An action potential could reach a cardiac muscle cell before it has entered the relaxation phase, resulting in the sustained contractions of tetanus. If this happened, the heart would not beat regularly.
How are cardiac muscle cells similar to and different from skeletal muscle cells? Cardiac and skeletal muscle cells both contain ordered myofibrils and are striated. Cardiac muscle cells are branched and contain intercalated discs, which skeletal muscles do not have. Skip to content Muscle Tissue. Learning Objectives By the end of this section, you will be able to: Describe intercalated discs and gap junctions Describe a desmosome.
Like skeletal muscle cells cardiocytes have a striated appearance, but their overall structure is shorter and thicker. Cardiocytes are branched, allowing them to connect with several other cardiocytes, forming a network that facilitates coordinated contraction. See more from our free eBook library. Newark: University of Delaware, Biological Sciences.
How do muscles grow? Len Kravitz, Ph. Muscle Attachment and Actions. Muscular System Pathologies. When you select "Subscribe" you will start receiving our email newsletter. Use the links at the bottom of any email to manage the type of emails you receive or to unsubscribe. See our privacy policy for additional details. Learn Site. Junction between two adjacent cardiac cells show intercalated discs where cytoplasmic bridges are present between cells.
This is why cardiac muscle cells form a functional syncytium. Majority of striated muscles act quickly. Involuntary muscles act slow. Their contraction is slow but sustained. On the other hand striated muscles contract fast. How does cardiac muscle differ from skeletal muscle? Biology Structure and Motion Muscles and Motion. Mandira P. Jul 29,
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