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Muscle Tissue and Function

Muscle Tissue and Function. Muscle Cell Architecture and Function Mechanics of muscle contraction—the “sliding filament” model and role of actin and myosin proteins Types of muscle cells Motor Units. are unique to animals have “excitable” membranes that transmit action potentials

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Muscle Tissue and Function

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  1. Muscle Tissue and Function Muscle Cell Architecture and Function Mechanics of muscle contraction—the “sliding filament” model and role of actin and myosin proteins Types of muscle cells Motor Units Human Anatomy, Larry M. Frolich, Ph.D.

  2. are unique to animals have “excitable” membranes that transmit action potentials allow for rapid large-scale movements Motor Unit is one motor neuron plus the muscle cells that it stimulates (or synapses with) Muscle Cells and Neurons Human Anatomy, Larry M. Frolich, Ph.D.

  3. Muscle cell or muscle “fiber” is composed of myofibrils which contain sarcomeres or contractile “units” Human Anatomy, Larry M. Frolich, Ph.D.

  4. Muscle fibers are cells—visible to naked eye as fibers in meat, chicken, fish Sarcolemma is muscle cell membrane—”excitable” so has action potentials just like neurons Because cell is large, T-tubules carry action potential—ionic depolarization—into internal parts of cell Sarcoplasmic reticulum releases calcium which triggers actin-myosin protein filaments to contract Muscle cells Sequence of events Motor Neuron to Muscle contraction at cellular level (from the Brain Top to Bottom) [link] Human Anatomy, Larry M. Frolich, Ph.D.

  5. Actin-Myosin “sliding filament” model EXPLAINS: MUSCLE SHORTENING MUSCLE FORCE GENERATION OR “CONTRACTION” Molecular Basis of Muscle Function Human Anatomy, Larry M. Frolich, Ph.D.

  6. Mechanics of Contraction (the sliding filament model) Action potential or depolarization of membrane triggers Ca release which causes actin and myosin to “slide” causing whole cell to“contract” Fig. 10.4 Human Anatomy, Larry M. Frolich, Ph.D.

  7. How actin-myosin complex (sarcomere) • shorten muscle • Ca triggers cross-bridges to form from myosin “thick” filament to actin “thin” filament • Cross-bridges “row” or “reach” for next binding site on actin “thin” filaments Human Anatomy, Larry M. Frolich, Ph.D.

  8. From Actin-Myosin to Whole Muscle Human Anatomy, Larry M. Frolich, Ph.D.

  9. Skeletal Muscle Tissue(each skeletal muscle is an organ) • Cells • Long and cylindrical, in bundles • Multinucleate • Obvious Striations • Skeletal Muscles-Voluntary • Connective Tissue Components: • Endomysium-between fibers • Perimysium-surrounds bundles • Epimysium-surround whole muscle • Attached to bones, fascia, skin • Origin & Insertion Human Anatomy, Larry M. Frolich, Ph.D.

  10. Smooth Muscle Tissue • Cells • Single cells, uninucleate • No striations • Smooth Muscle-Involuntary • 2 layers-opposite orientation (peristalsis) • Surrounds hollow organs, blood vessels • Connective Tissue Component • Endomysium: surrounds cells Human Anatomy, Larry M. Frolich, Ph.D.

  11. Cardiac Muscle • Cells • Branching, chains of cells • Single or Binucleated • Striations • Connected by Intercalated discs • Cardiac Muscle-Involuntary • Myocardium-heart muscle • Pumps blood through vessels • Connective Tissue Component • Endomysium: surrounding cells Human Anatomy, Larry M. Frolich, Ph.D.

  12. Human Anatomy, Larry M. Frolich, Ph.D.

  13. Carciac Muscle Smooth Muscle Human Anatomy, Larry M. Frolich, Ph.D.

  14. Human Anatomy, Larry M. Frolich, Ph.D.

  15. Human Anatomy, Larry M. Frolich, Ph.D.

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