30 Questions
What is the primary action of skeletal muscle relaxants?
Decrease skeletal muscle tone
What is the primary function of cholinesterase in the neuromuscular junction?
Inactivate acetylcholine
Which type of skeletal muscle relaxant acts directly on skeletal muscle?
Dantrolene
What is the mode of action of competitive blockers?
Compete with acetylcholine for binding to receptors
Which of the following is a centrally acting skeletal muscle relaxant?
Tizanidine
What is the outcome of the binding of acetylcholine to NM receptors at the NMJ?
Depolarization and development of end-plate potential
What is the purpose of using muscle relaxants in fracture of mandible?
To facilitate opening of the mouth for diagnosis and treatment
What is succinylcholine used for during electroconvulsive therapy?
To prevent trauma due to convulsions
What is the mechanism of action of botulinum toxin A?
It inhibits the release of ACh into the synaptic cleft
What is the purpose of administering botulinum toxin A intradermally?
To produce an antiwrinkle effect in cosmetic procedures
What is the purpose of prior atropine administration when reversing the action of competitive neuromuscular blockers?
To block the muscarinic effects of anticholinesterases
What is the adverse effect of botulinum toxin A injection?
Pain at the site of injection
What is the cause of sinus bradycardia?
Vagal stimulation
What is the treatment for malignant hyperthermia?
Intravenous dantrolene, rapid cooling, inhalation of 100% oxygen and control of acidosis
What is the mechanism of action of dantrolene in producing skeletal muscle relaxation?
Inhibiting depolarization-induced Ca2+ release from the sarcoplasmic reticulum
What is the order of muscles affected by competitive blockers?
Extrinsic eye muscles, neck, face, hands, feet, limbs, trunk, respiratory
What is the life-saving drug in malignant hyperthermia?
Dantrolene
What is the effect of d-tubocurarine, mivacurium, and atracurium on histamine?
They cause histamine release
What is the duration of action of succinylcholine?
3-8 minutes
What is the purpose of washing the bath several times after adding succinylcholine in the frog rectus abdominis preparation?
To remove the effect of succinylcholine
What is the main use of neuromuscular blockers?
As adjuvant to general anaesthesia for producing satisfactory skeletal muscle relaxation
What is the condition of the basal contraction of the muscle in the frog rectus abdominis preparation?
Isometric
What is the reason for muscle pain caused by succinylcholine?
Initial fasciculation
What is the preferred neuromuscular blocker for short procedures?
Succinylcholine
Which of the following skeletal muscle relaxants is contraindicated in patients with myasthenia gravis?
Any skeletal muscle relaxant
What is the result of slow metabolism of succinylcholine in people with liver disease or atypical pseudocholinesterase?
Prolonged apnea
What is the antidote for succinylcholine apnoea?
No antidote available
What is the effect of aminoglycosides on neuromuscular blockers?
They potentiate the effect of neuromuscular blockers
What is the mechanism of action of succinylcholine?
Depolarization of NM receptors
What is the effect of succinylcholine on intragastric pressure?
Increased intragastric pressure
Explore the physiology of the neuromuscular junction and learn how skeletal muscle relaxants work, including their mechanisms of action and clinical applications. This quiz covers the effects of different neuromuscular blocking agents and their uses.
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