BIOL 404-Exam 4-Muscle 3

  1. What type of junctions are always excitatory?
    Neuromuscular junctions
  2. What breaks down acetylcholine in the neuromuscular junction?
  3. What does Acetylcholinesterase do?
    Beak down acetylcholine in the synaptic cleft
  4. What is Acetylcholine broken down by in the synaptic cleft in the nervous system?
  5. What type of receptors does acetylcholine bind to?
  6. The binding of Acetylcholine to nicotinic receptors on the motor end plate causes what?
    • Increased muscle membrane permeability to Na and K (Na in, K out)
    • Depolarization
  7. What is the purpose of increasing the permeability of the Na and K in the muscle fiber?
    To create a propagating action potential in the muscle fiber and into the T-tubules
  8. What happens when an action potential moves into a T-tubule?
    • It activates DHP receptors that pull open ryanodine receptors
    • Leads to release of Ca from sarcoplasmic reticulum
  9. What is the force generated by muscle that opposes a load?
  10. What is tension?
    The force that opposes a load
  11. What is the mechanical response of a muscle fiber to a single action potential called?
    A twitch
  12. What is a twitch?
    A mechanical response of a muscle fiber to one action potential
  13. What are the three phases of a twitch?
    • Latent period
    • Contraction phase
    • Relaxation phase
  14. What is the Latent period of a twitch?
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    • The period between an action potential and contraction
  15. What is the Contraction phase of a twitch?
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    • The time that tension is developing due to cross-bridge cycling
  16. What is the twitch stage that is defined as the time that tension is developing due to cross-bridge cycling?
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    • Contraction phase
  17. What is the relaxation phase of a twitch?
    • The time the tension is decreasing
    • Due to the time it takes for Calcium to be pumped back into the SR
  18. What is the term for the period during a twitch that is dependent on the time it takes to pump Ca back into the SR?
    The Relaxation Phase
Card Set
BIOL 404-Exam 4-Muscle 3
BIOL 404-Exam 4-Muscle 3