Muscletissue2
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Muscletissue2

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Muscletissue2 Muscletissue2 Presentation Transcript

  • The Muscle Tissue
  • Types of Muscle Tissues: 1.) Skeletal Muscle Striated Long cylinder shaped Multinucleated and peripherally located Contraction: Voluntary ( none or all) Mitosis: no Nerve fibers: Somatic motor Sarcomere: yes Regeneration: Yes derived from the somatic mesoderm
  • Terms used in Muscle cell: Sarcolemma- muscle cell membrane Sarcoplasm- the muscle cytoplasm Sarcoplasmic reticulum- the muscle endoplasmic reticulum Sarcosomes- muscle mitochodria Myoglobin- oxygen transporting proteins that resemble but are smaller than hemoglobin
  • The skeletal muscle: myoblasts- precursor of the skeletal muscle fibers myotubes- myoblasts that lined up end to end and have fused with one another. thay manufacture cytoplasmic constituents myofibrils- composed of arrays myofilaments Myofilaments- proteins responsible for the contractile capability of the cell
  • Types of Muscle Fibers:  A.) Red muscle fiber-  Rich in myoglobin  numerous mitochondria  Rich in oxidative, weak ATPase  Contraction: Slow but repetitive, not easily fatigued  B.)White muscle fiber  Poor in myoglobin  Poor in mitochondria  Poor in oxidative, rich in phosphorylases and Atase  Fast but easily fatigued
  • Types of Muscle Fibers C.) Intermediate Intermediate in myoglobin, mitochodria, enzymes and contraction
  • Structures found in the Skeletalmuscle: epimysium- a dense irregular collagenus connective tissue that surrounds the entire muscle Perimysium- a less dense collagenous connective tissue derived from the epimysium that surrounds bundles ( fascicles ) of muscle fibers endomysium- composed of reticular fibers ad an external lamina ( basal lamina) that surrounds each muscle cell
  • Structures found in the SkeletalMuscle satellite cells- small cell which possess a single nucleus and act as regenerative cells located in the shallow depressions on the muscle cells surface. Myofibrils- longitudinally they compose the skeletal muscle cell and they constitute the cross- striations of light and dark banding. A bands- The dark bands ( anisotropic with polarized light I bands – The light bands ( isotropic with polarized light)
  • Structures found in Skeletal Muscle H band- pale area at the center of each A band M line- a thin line that bisects the H band Z disk ( Z line)- a thin line that bisects the I band Sarcomere- the region of the myofbril between two successive Z disks T tubules ( transverse tubules) -long tubular invaginations that intertwine among the myofibrils esmin and Vimentin -itermediate filaments that hold myofirils with each other which secure the periphery of the Z disks of neighboring myofibrils to each other.
  • Structural Organization of themyofibrils Thick filaments- 15nm in diamter and 1.5 um long composed of myosin.Composed of two identical heavy chains and two pairs of light chains Thin filaments- 7nm in diameter and 1.0 um long and are composed primarily of actin.originates from the Z disk. ajor component if the F-actin, a polymer of the G-actin Sliding filament theory- During contraction , individual thick and thin filaments do not shorten, instead, the two Z disks are brought closer together as the thick and thin filaments slide past each other
  • Structural Organization of themyofibrils Tropomyosin molecule- occuy the shallow grooves along the length of the double strand F- actin helix. Troponin molecule- found approximately at the beginning of each troponin molecule ( about 25 to 30 nm from the beginning). composed of three globular polypeptides: TnT, TnC, TnI
  • Proteins associated with theSkeletal Muscle: 1.Myosin- Major protein of the thick filament; its interaction with actin hydrlyzes ATP and produces contraction 2.Myomesin- Cross-links adjacent thick filaments at the M-line 3.Titin-Forms an elastic lattice that anchors thick filaments to Z disks 4. C protein- Binds to thick filaments at the M line 5.G-Actin- polymerizes to form thin filaments of F-actin; interaction of G-actin with myosin assists in hydrolyzing ATP, resulting in contraction
  • Proteins associated with theSkeletal Muscle: 6.Tropomyosin-Occupies the groove of the thin filaments 7.Troponin- Binds calcium; binds to tropomyosin; binds to actin, thus inhibiting actin-myosin interaction 8. alpha Actinin- Anchors plus ends of thin filaments to Z disk 9. Nebulin- Z disk protein that may assist alpha ctinin anchr thin filaments to Z disk
  • Muscle spindle Muscle spindle- initiates the stretch reflex. - an encapsulated sensory receptor located among the muscle cells
  • Cardiac muscle myocardium- mpsed of anastomosing netwok of branching cardiac muscle cells arranged in layers( basal lamina) atrial muscles- smaller than ventricle cells and house granules containing atrial natriuretic peptide which functions to lower blood vessels by decreasing the capabilities of the the renal tubules to resorb sodium and water. Has 1 to 2 nuclei, centrally located branched cells nerve fiber: Autonomic Striated because of actin and myosin
  • Smooth Muscle non-striated has one centrally located nucleus capable f regeneration undergoes mitosis fusiform cells with no striations and 1 nucleus All or none law does not apply to this muscle Troponin is absent cork-screw appearance of nuclues during contraction each fiber is surrounded by external lamina embedded with numerous reticular fibers lying beneath the cell membrane are structures that may be associate with sparse sarcoplasmic retculum . function in the release and sequestering of calcium