Block 15 Local Anesthetics MCQ's

17 Questions | Total Attempts: 1357

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Block 15 Local Anesthetics MCQ

William T. G Morton was the first person in the world to successfully demonstrate the use of ether anesthesia for surgery. Today anesthetics render a patient unresponsive and unconscious, most patients may have amnesia and feel no pain. Jog your memory on block 15 on local anesthetics by taking up the simple quiz below.


Questions and Answers
  • 1. 
    • A. 

      Ventricular tachycardia

    • B. 

      Abdominal colic

    • C. 

      Drowsiness

    • D. 

      Tonic-clonic convulsions

    • E. 

      Nystagmus

  • 2. 
    • A. 

      Inactivated, voltage-gated, Na+ channels

    • B. 

      Inactivated, ligand-gated, K+ channels

    • C. 

      Resting, voltage-gated, K+ channels

    • D. 

      Resting, ligand-gated, Na+ channels

    • E. 

      Activated, ligand-gated, Ca2+ channels

    • F. 

      Activated, voltage-gated, Ca2+ channels

  • 3. 
    Which of the following nerve fibers are most sensitive to the action of local anesthetics?
    • A. 

      Resting fibers

    • B. 

      Rapidly firing fibers

    • C. 

      Fibers with high conduction velocity

    • D. 

      Unmyelinated fibers

    • E. 

      Fiber of large diameter

  • 4. 
    When a local anesthetic is applied to a nerve fiber, which of the following nerve properties will most likely increase?
    • A. 

      Rate of rise of the action potential

    • B. 

      Conduction velocity of the nerve

    • C. 

      Amplitude of the action potential

    • D. 

      Resting potential of nerve membrane

    • E. 

      Refractory period of the nerve

  • 5. 
    Which of the following functions is blocked last when a local anesthetic is applied to a nerve?
    • A. 

      Motor function

    • B. 

      Pain sensation

    • C. 

      Muscle tone

    • D. 

      Temperature sensation

    • E. 

      Sympathetic activity

  • 6. 
    Which of the following molecular events makes the nerve membrane more sensitive to the action of local anesthetics?
    • A. 

      Increased extracellular concentration of Ca2+

    • B. 

      Increased extracellular concentration Na+

    • C. 

      Decreased extracellular concentration of Cl-

    • D. 

      Increased extracellular concentration of K+

    • E. 

      Increased extracellular concentration of Mg2+

  • 7. 
    A main feature of the mechanism of action of local anesthetics is a voltage dependent blockade of Na+ channels. Which of the following statements best explains this voltage dependency?
    • A. 

      The more negative the membrane potential, the lower the affinity for local anesthetics

    • B. 

      The more negative the membrane potential, the higher the affinity for local anesthetics

    • C. 

      The higher the frequency of firing of the fiber, the lower the affinity for local anesthetics

    • D. 

      The lower the frequency of firing of the fiber, the higher the affinity for local anesthetics

    • E. 

      The faster the conduction velocity of the fiber, the higher the affinity for local anesthetics

  • 8. 
    The ionized form of local anesthetics is mainly responsible for which of the following properties of the drug?
    • A. 

      Tissue redistribution

    • B. 

      Liver biotransformation

    • C. 

      Systemic toxicity

    • D. 

      Receptor binding

    • E. 

      Half-life

  • 9. 
    Which of the following statements best explains why the onset of the therapeutic effect of a local anesthetic is usually slower in infected tissues?
    • A. 

      They are very rich in drug-metabolizing enzymes

    • B. 

      They are poorly vascularized, so that the drug slowly reaches the nerve terminals

    • C. 

      They are rich in extracellular K+ which lowers the drug-receptor binding

    • D. 

      They have a low extracelluar pH, which hinders drug diffusion into the cell

    • E. 

      They have a high extracellular pH, which hinders drug diffusion into the cell

  • 10. 
    The pKa of lidocaine is 7.9. Which fraction of the drug will be in the lipid soluble form in the extracellular fluids (pH = 7.4)?
    • A. 

      10%

    • B. 

      24%

    • C. 

      50%

    • D. 

      76%

    • E. 

      90%

  • 11. 
    • A. 

      Cocaine

    • B. 

      Bupivacaine

    • C. 

      Procaine

    • D. 

      Tetracaine

    • E. 

      Benzocaine

  • 12. 
    Which of the following is the most cardiotoxic local anesthetics drug?
    • A. 

      Benzocaine

    • B. 

      Procaine

    • C. 

      Tetracaine

    • D. 

      Lidocaine

    • E. 

      Bupivacaine

  • 13. 
    A 14-year-old boy complained of burning pain due to multiple superficial skin abrasions, after a motorcycle accident. Which of the following local anesthetics would be appropriate for this boy?
    • A. 

      Benzocaine

    • B. 

      Procaine

    • C. 

      Cocaine

    • D. 

      Prilocaine

    • E. 

      Bupivacaine

  • 14. 
    Which of the following are the main purposes for adding a vasoconstrictor drug to a local anesthetic? (Check all that apply)
    • A. 

      To speed up the onset of the anesthetic effect

    • B. 

      To increase the duration of anesthetic effect

    • C. 

      To decrease the risk of systemic overdose toxicity of the drug

    • D. 

      To decrease the risk of allergic reactions of the drug

    • E. 

      To increase the affinity of the drug for the Na+ channels

  • 15. 
    Which of the following systems are more likely involved when a toxic dose of a local anesthetic is inadvertently given IV? (Check all that apply)
    • A. 

      Gastrointestinal system

    • B. 

      Respiratory system

    • C. 

      Urinary system

    • D. 

      Immune system

    • E. 

      Cardiovascular system

    • F. 

      CNS

  • 16. 
    • A. 

      Procaine

    • B. 

      Tetracaine

    • C. 

      Lidocaine

    • D. 

      Benzocaine

    • E. 

      Proparacaine

  • 17. 
    A 65-year-old man is scheduled for a lithotripsy to shatter a bladder stone. Lumbar epidural anesthesia is selected for the procedure. Since the anticipated duration of the procedure is about 30 minutes,  which of the following drugs should be used?
    • A. 

      Cocaine

    • B. 

      Procaine

    • C. 

      Benzocaine

    • D. 

      Tetracaine

    • E. 

      Lidocaine