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Muscle Tissue

Muscle Tissue. Li dongmei. Muscle function. contraction for locomotion and skeletal movement contraction for propulsion contraction for pressure regulation. Overview of muscle tissue. Composition: muscle cells + connective tissue. The myocytes is also called muscle fibers.

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Muscle Tissue

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  1. Muscle Tissue Li dongmei

  2. Muscle function • contraction for locomotion and skeletal movement • contraction for propulsion • contraction for pressure regulation

  3. Overview of muscle tissue • Composition: muscle cells + connective tissue. • The myocytes is also called muscle fibers. • The cytoplasm is called sarcoplasm, and the smooth endoplasmic reticulum is called sarcoplasmic reticulum. The sarcolemma is the cell membrane.

  4. Classification

  5. Two principal types:

  6. Skeletal muscle-connective tissue • The skeletal muscle fibers are held by connective tissue named as: endomysium, perimysium and epimysium.

  7. Endomysium perimysium epimysium.

  8. Skeletal muscle • Long, cylindrical fibers, multinucleated syncytium. • The nuclei are located in the cytoplasm beneath the sarcolemma.

  9. Skeletal muscle-myofibrils The structural and functional subunit of the muscle fiber. They contribute to the formation of cross-striation. Cross-striations: composed of alternatingdark (A) and light (I) bands.

  10. Skeletal muscle-sarcomere • The sarcomere is the segment of the myofibril between two adjacent Z lines. • It is the basic contractile unit of striated muscle. • It consists of 1/2 I band + A band + 1/2 I band.

  11. Light band: I band • Z line: I band is Intersected by a thin dark line • Dark band： A band • H band： a pale thin H-band bisects the A-band • M line： a very fine dark stripe is present in the middle of the H-band.

  12. Skeletal muscle-myofilaments • Two types of myofilaments are associated with cell contraction. • They are thin filaments and thick filaments.

  13. Skeletal muscle-contraction • When a muscle contracts, each sarcomere shortens and becomes thicker, but the myofilaments remain the same length.

  14. Skeletal muscle -sarcoplasmic reticulum • sarcoplasmic reticulum • ---A series of networks around the myofibrils. • ---Network of smooth endoplasmic reticulum • At the junction between A and I bands, they fused to form terminal cisterna.

  15. Skeletal muscle -transverse tubule system • It consists of numerous tubular invaginations of the plasma membrane, each one is called a T tubule. • They located between adjacent terminal cisternae. • Responsible for rapid conduction of impulses

  16. Skeletal muscle -transverse tubule system • The complex of T tubule and the two adjacent terminal cisternae is called a triad.

  17. Cardiac muscle • The cardiac muscle cell present short rod withbranch, which links with each other. • There is only one nucleus in the centre of thecardiac muscle cell. • The present of dark staining transverse orsteplike lines at the interface between adjacent cardiac muscle cells are called intercalated disks. • The cross-striation of cardiac muscle cells isless obvious than striated skeletal muscle.

  18. Similarities between cardiac muscle and skeletal muscle • Made up of elongated fibers. • Myofibrils show transverse striations. • Myofibrils also made up of thin and thick filament.

  19. Differences between cardiac muscle and skeletal muscle • The fibers branch and anastomose with other fibers to form a network. • Each cardiac muscle cell possesses only one centrally located nucleus. • Myofibrils and striations are not distinct. • The sarcoplasmic reticulum is less prominent.

  20. Differences between cardiac muscle and skeletal muscle • It possesses diads composed of one T tubule and one terminal cisterna. • A unique and distinguishing characteristic is the presence of intercalated disks.

  21. intercalated disks diads

  22. Smooth muscle • Smooth muscle cells are fusiform. Each cell has a single nucleus located in the center of the broadest part of the cell.

  23. Smooth muscle • In smooth muscle cells, bundles of myofilaments crisscross through the cell, forming a latticelike work. • The cytoskeleton contains cytoplasmic densities or dense bodies, intermediate filaments. • Smooth muscle cells have a membrane system of sarcolemmal invaginations, vesicles, and SER but lack a T system.

  24. Summary • The structure of skeletal muscle. • The structure of cardiac muscle. • The structure of smooth muscle.

  25. Exercise 3 for Histology • 1.What do blood cells include? • 2.The structure of sarcomere.

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