Chapter 4 - Muscle Tissue
Muscle cells synthesize and maintain the contractile function of connective tissue. Three types of muscle are recognized based on their distinctive structural and functional features: skeletal, cardiac and smooth muscle.
Skeletal and cardiac appear striated because of the parallel arrangement of contractile filaments appear as an alternating series of transverse bands. Smooth muscle appears non-striated because of the less ordered array of contractile filaments.
The terms muscle fiber and muscle cell are synonymous.
Skeletal Muscle
Skeletal muscle is composed of large, multinucleated cells with the nuclei located at the periphery. The parallel arrangement of contractile filaments produces striations of alternating transverse bands. Light microscopy can resolve these bands.
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(longitudinal and cross section) |
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(longitudinal section) |
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(phosphotungstic acid) |
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(longitudinal section) |
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(cross section) |
Skeletal Muscle Fibers
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Muscle Insertion
A muscle insertion is where muscle fibers connect to a tendon attached to a bone.
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Cardiac Muscle
Cardiac muscle is composed of branched, mononuclear cells (occasionally bi-nucleate) with the nuclei located in the center of the cell. The cells show the same striations as skeletal muscle.
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(longitudinal and cross sections) |
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(phosphotungstic acid) |
Purkinje Fibers
Purkinje fibers are specialized cardiac muscle cells that convey electrical impulses that coordinate cardiac muscle contraction.
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(periodic acid-Schiff's stain) |
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(phosphotungstic acid) |
Smooth Muscle
Smooth muscle contains the same contractile proteins (actin and myosin) as skeletal and cardiac muscle, but the less ordered array of contractile filaments does not produce striations.
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