muscular tissue part 2

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Wesleypjones
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208171
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muscular tissue part 2
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2013-03-18 23:15:13
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muscular tissue part
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muscular tissue part 2
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  1. sarcomeres
    the basic functional units of a myofibril
  2. z-disc
    narrow plate shaped regions of dense protein material separate of sarcomere from the next. thus a sarcomere extends from one of these to the next
  3. A-band
    the darker middle part of the sarcomere which extends the entire length of the thick filaments.
  4. I-band
    is a lighter, less dense area that contains the rest of the thin filaments but no thick filaments. A z-disc bases through the center of each of these bands.
  5. H-zone
    in the centre of each band contains thick but no thin filaments
  6. M-line
    it is the middle of the sarcomere
  7. myosine
    one of two contractile proteins, it functions as a motor protein in all three types of muscle tissue. They push or pull various cellular structures.  They form a single thick filament
  8. myosine heads
    the two projections of each myosin molecule.  they extend towards the thin filaments.
  9. actin
    thin filaments attached to z-discs have this protein. this type of molecules join together to forma filament that is twisted together into a helix.  Each molecule has a myosine-binding site where a myosin head can attach
  10. tropomyosin
    a regulating protein. It covers the myosin binding sites in relaxed muscles.  they are held in place by troponin molecules.  When bound with ca 2 troponin changes shape which causes this to move away from the myosin head binding site
  11. sliding filament mechanism of muscle contraction
    • 1. myosin heads hydrolyze atp and become reoriented and energized
    • 2. myosin heads bind to actin, forming crossbridges
    • 3.myosin crossbridges rotate toward center of sacromere
    • 4. as myosin heads bind atp  the crossbridges detach from actin
  12. excitation-contraction coupling
    an increase in ca 2 concentration in the cytosol starts muscle contraction and a decrease stops it.
  13. neuromuscular junction
    the synapses between a somatic motor neuron and a muscle fiber
  14. somatic motor neuron
    the neurons that stimulate muscle fiber contraction
  15. synaptic cleft
    at most synapses a small gap separates the two cells
  16. neurotransmitter
    because the cells do not physically touch the action potential cannot jump the gap.  Instead the first cell communicates with the second by releasing a chemical called this
  17. synaptic vesicle
    suspended in the cytosol within each synaptic end bulb are hundreds of membrane enclosed sacs
  18. Ach
    inside each synaptic vesicle are thousands of moleculesod this, a neurotransmitter released at the ends of axons
  19. motor end plate
    the region of the sarcolemma opposite the synaptic end bulbs.  It is the muscle fiber part of the neuromuscular junction.
  20. Ach receptor
    within each motor end plate are these. Integral transmembrane proteins bind specifically to Ach.
  21. muscle action potential
    the inflow on Na+ makes the inside of the muscle fiber more positively charged.  This change in the membrane potential triggers this.
  22. AchE
    an enzyme that breaks down Ach. This enzymeis attached to collagen fibers in the extracellular matrix of the synaptic cleft

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