bio chpt 9

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  1. what is the intercellular connection between motor neuron and skeletal muscle fiber
    neuromuscular junction
  2. what is it called when a muscle fiber contracts only under its control
    neuromuscular junction
  3. there is only one of these per muscle fiber
    neuromuscular junction
  4. what are the three components of the neuromuscular junction
    synaptic terminal of neuron, motor end plate of muscle fiber, and synaptic cleft
  5. what neuromuscular junction component has vesicles filled with neurotransmitter (acetylcholine[ACh]) and changes permeability of sarcolemma
    synaptic terminal of neuron
  6. what neuromuscular junction component has junctional folds and contains acetylcholinesterase (AChE) and enzyme that breaks down ACh
    motor end plate of muscle fiber
  7. what neuromuscular junction component has spaces between neuron and muscle fiber and contains AChE
    synaptic cleft
  8. #1. electrical impulses (actin potential) at the synaptic terminal causes vesicles of ACh to fuse with neuron plasma membrane 
    =exocytosis of ACh
    Activities at the NMJ
  9. #2. ACh diffuses across synaptic cleft and binds to receptors in motor end plate. ACh binding allows NA+ to diffuse into the cell
    Activities at the NMJ
  10. #3. sarcolemma generate action potential, AChE inactivates receptors by quickly removing ACh from synaptic cleft
    Activities at the NMJ
  11. what is generated at motor end plate that sweeps across sarcolemma
    Action potential
  12. What is an immediate effect due to electrical event and an event is brief since ACh has been removed and no other stimulus occurs until another AP at motor end plate
    action potential in the muscle cell
  13. what action potential sweeps down t tubules and causes calcium to be released from SR to sarcomeres causing muscle contraction
    Excitation-contraction coupling
  14. #1. contaction cycle begins. arrival of calcium ions at zone of overlap
    Muscle fiber contraction cycle
  15. #2. Active site exposure. calcium binds to troponin. weakens bond between actin and troponin-tropomyosin complex. troponin changes position, exposing active sites to actin
    Muscle fiber contraction cycle
  16. #3. Cross-Bridge Formation. myosin heads bind to expose active sites on actin forming cross-bridges
    Muscle fiber contraction cycle
  17. #4. Myosin Head pivoting. stored energy within myosin head releases and head pivots toward M line = power stroke. ADP and P are released from myosin head
    Muscle fiber contraction cycle
  18. #5. Cross-bridge detachment. attachment of new ATP causes release of myosin from actin. exposes active sites again for formation of another cross-bridge
    Muscle fiber contraction cycle
  19. #6. Myosin reactivation. new ATP broken down and head recocks
    Muscle fiber contraction cycle
  20. what sarcomere has each myosin head already "energized" and "cocked" head points to M line
    resting sarcomere
  21. what sarcomere has energy supplied by breakdown of ATP by myosin
    resting sarcomere
  22. what sarcomere has myosin acting as an ATPase, breakdown products (ADP and P) still attached to myosin head
    resting sarcomere
  23. what sarcomere has entire cycle repeated as long as Ca2+ concentrations remain high and ATP is available
    contracted sarcomere
  24. what sarcomere once stimulus is removed SR calcium channels close, calcium pumps move Ca2+ from sarcoplasm into terminal cisternae
    contracted sarcomere
  25. what sarcomere has troponin-tropmyosin complex moves to cover active sites; preventing further cross-bridge formation
    contracted sarcomere

Card Set Information

bio chpt 9
2013-11-19 23:38:41
neuromuscular junction

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