Dr Gawad Physiology Course Online Exam - Excitable - Course Lecture 5

7 Questions | Total Attempts: 188

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Physiology Quizzes & Trivia

7 MCQs (Only one correct answer)Each MCQ: 1 mark, Total mark: 7 (you will get the results immediately with correction by the web)Allowed time: 10 minGood Luckdr Mohammed Abel Gawad


Questions and Answers
  • 1. 
    In the motor end plate, all the following are TRUE EXCEPT:
    • A. 

      The acetylcholine receptors are similar to those in smooth muscle.

    • B. 

      The nerve ending contains many vesicles and mitochondria.

    • C. 

      Lack of Ca diminishes the release of acetylcholine.

    • D. 

      There is a high concentration of the cholinesterase enzyme.

    • E. 

      There is a delay of neuromuscular transmission of 0.5 millisecond

  • 2. 
    About neuromuscular transmission and end plate potential (EPP):
    • A. 

      Neuromuscular transmission occurs only from the muscle to the nerve.

    • B. 

      EPP is always maximal and rapidly conducted along the surface of the muscle.

    • C. 

      EPP is a localized state of depolarization at the motor end plate.

    • D. 

      EPP is augmented by increased Mg concentration in ECF.

    • E. 

      EPP is associated with decreased excitability of the motor end plate.

  • 3. 
    About activation of skeletal muscles, all the following is true except:
    • A. 

      The resting membrane potential is about -90 mV.

    • B. 

      The magnitude of the action potential is more than that in nerves.

    • C. 

      The firing level is reached after about +40 mV of depolarization.

    • D. 

      The spike is propagated along the muscle surface at a speed of 5 m /second.

  • 4. 
    The action potential of skeletal muscles:
    • A. 

      Has a prolonged plateau phase.

    • B. 

      Has a smaller magnitude than that of smooth muscles.

    • C. 

      Causes uptake of Ca into the lateral sacs of the sarcoplasmic reticulum.

    • D. 

      Spreads inwards to all parts of the muscle fibre via the T-tubules.

    • E. 

      Is not essential for contraction.

  • 5. 
    Neuromuscular transmission:
    • A. 

      Is caused by release of acetylcholine from the muscle side.

    • B. 

      Shows a permeability change to Na+ at the receptor side of the neuro-muscular junction

    • C. 

      Can be facilitated by curare.

    • D. 

      Is blocked by curare because it competes with Na+ influx at the M.E.P.

  • 6. 
    The neurotransmitter at the motor endplate is:
    • A. 

      Adrenaline.

    • B. 

      Noradrenaline.

    • C. 

      Acetyl choline.

    • D. 

      Calcium ions.

    • E. 

      Atropine.

  • 7. 
    During neuromuscular transmission:
    • A. 

      Ca++ enters through synaptic cleft.

    • B. 

      Ach is released from synaptic cleft.

    • C. 

      There is a delay of about 5 milliseconds.

    • D. 

      The impulse is transmitted in one direction.

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