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Muscular Tissue

Muscular Tissue. General description 1) components : ---cell: muscle fiber--myofiber elongated thread-liked sarcolemma sarcoplasm SER : sarcoplasmic reticulum ---extracellular G.S: CT with BV, LV and N. 2) classification According to the structure and function

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Muscular Tissue

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  1. Muscular Tissue

  2. General description 1) components: ---cell: muscle fiber--myofiber • elongated thread-liked • sarcolemma • sarcoplasm • SER : sarcoplasmic reticulum ---extracellular G.S: CT with BV, LV and N

  3. 2) classification According to the structure and function • skeletal muscle: striated voluntary m. • cardiac muscle: striated involuntary m. • smooth muscle: unstriated involuntary m. smooth muscle skeletal muscle cardiac muscle

  4. Skeletal muscle

  5. Often called Striated or Voluntary Muscle • Has striations that are visible under light microscopy • Under voluntary control • Attached to skeleton ( skeletal)

  6. Characteristics of Skeletal Muscles Muscle cells are elongated fibers with many peripheral nuclei Each muscle fiber contains many myofibrils Each myofibril contains many microfilaments

  7. Connective tissue coverings (responsible for force transduction): Epimysium: surround collection of fascicles Perimysium: surround fascicle Endomysium: surround individual fibers

  8. epimysium Perimysium Entire muscle Endomysium Fasciculus of muscle fibres A muscle fibre

  9. 1)microstructure of skeletal muscle fiber ①long cylindrical 10-100um in diameter,1-40mm long ②multinucleate, nuclei are ovoid, distributed under sarcolemma ③ filled with longitudinal parallel-arranged myofibrils

  10. Longitudinal section Transverse section

  11. muscle fiber myofibril Thin Filaments Thick Filaments

  12. myofibril: • 1-2um in diameter • cross striation: light band -I band, dark band- A band

  13. --A band: M-line, H-band --I band: Z-line I band A band H-band Z-line M-line

  14. --A band (except H band): Thin Filaments Thick Filaments H band: only Thick Filaments --I band: only Thin Filaments

  15. sacromere sacromere:1/2 I band, A band ,1/2 I band the smallest structural and functional unit of myofibril

  16. 2)Ultrastructure of myofiber myofibril: ---thick myofilament: • composed of myosin: ---thin myofilament: • Compose of • A. actin • B. tropomyosin • C.troponin:

  17. Transverse tubule (T tubule): ---definition: sarcolemma and basement membrane invaginate into sarcoplasm to form a transverse distributed tubular system ---location:A-I junctional part ---function: transfer the information into cytoplasm

  18. ③Sarcoplasmic reticulum: ---definition: A longitudinal distributed tubular system formed by smooth endoplasmic reticulum Sarcoplasmic reticulum

  19. ---structure: • H-A band: longitudinal enclose myofibril-- longitudinal tubule • A-I junction: enlarge to form flattened sac —terminal cisternae • triad: one T-tubule + two terminal cisternae • ---function: there are calcium pump proteins (ATPase) on membrane, so it can store and release calcium ions triad

  20. Cardiac muscle

  21. 1) Microstructure of cardiac muscle • ①short column in shaped, 100um long,15um in diameter, with branches, the branches associated with each other to form a network • ②1-2 ovoid nuclei, centrally-located • ③striated, but no very clear • ④intercalated disc: junctional part • LM: dark striation across the cardiac fibers

  22. Cardiac muscle

  23. Cardiac muscle: show intercalated disc

  24. 2) Ultrastructure of cardiac muscle similar to skeletal muscle, composed of thick, thin filament and have sarcomere ①myofibril have different diameter, the boundary of myofibril is not very clear

  25. diad ②transverse tubule are thicker, located at Z-line level (skeletal muscle : A-I junctional part) ③sarcoplasmic reticulum is not well-developed, form less terminal cisternae ④diad: one T-tubule + one terminal cisternae (skeletal muscle : triad) cardiac muscle triad skeletal muscle

  26. ④ intercalated discs

  27. transverse portion: connection -intermediate junction -desmosome longitudinal portion: communication -gap junction transverse portion longitudinal portion

  28. Smooth muscle

  29. microstructure of smooth muscle ①elongated, spindle-shaped cells, 8um in diameter, 200( 20-500)um long ②rob-liked or ovoid nucleus ③no striation, no myofibril

  30. 2) ultrastructure of smooth muscle ①caveola on sarcolemme invaginate into cytoplasm ②dense patch: under sarcolemma dense body: in sarcoplasm ③intermediate filament: caveola dense body dense pach

  31. smooth muscle under SEM

  32. Compare with three muscle tissues

  33. 1. The location of T tubules of cardiac muscle differ from those of skeletal muscle, the former lie at the • A. A-I junctions B.I bands • C. A bands D.M lines • E. Z lines √

  34. 2. Sarcoplasmic reticulum of muscle fiber is composed of • A. lysosome B. mitochondria • C. microsome D. RER • E. SER √

  35. 3.The cell junction which transmit rapidly an electrical impulse between adjacent smooth muscle cells is • A. tight junction B. intermediate junction • C. gap junction D. desmosome • E. semidesmosome √

  36. Questions: • Describe the characteristics of muscle tissue. • Compare the similar with the difference for three kinds of muscle cells according to their fine structure and ultrastructure.

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