Neuromuscular blocking agents — MCQs

Which receptor type mediates the slow phase of synaptic transmission in autonomic ganglia?

During a nerve conduction study, which of the following ions is primarily responsible for the rapid upstroke of the action potential?

A neurophysiologist describes the mechanism of a specific type of synaptic transmission to his students. While illustrating this, he points out that when the action potential reaches the presynaptic terminal of a chemical synapse, the voltage-gated Ca2+ channels open. Ca2+ ions trigger the release of neurotransmitters from vesicles in the presynaptic terminal. In this type of synaptic transmission, increased cytosolic Ca2+ levels cause the release of a neurotransmitter from small vesicles with dense cores. Which of the following neurotransmitters is most likely to be the one that is released into the synaptic cleft in this type of synapse?

A 16-year-old boy is brought to the emergency department by ambulance with a visible deformity of the upper thigh after being involved in a motor vehicle collision. He is informed that he will require surgery and is asked about his medical history. He mentions that he had surgery to remove his tonsils several years ago and at that time suffered a complication during the surgery. Specifically, shortly after the surgery began, he began to experience severe muscle contractions and an increased body temperature. Based on this information, a different class of muscle relaxants are chosen for use during the upcoming surgery. If these agents needed to be reversed, the reversal agent should be administered with which of the following to prevent off-target effects?

A 59-year-old woman is scheduled to undergo a right hip total arthroplasty for severe hip osteoarthritis that has failed conservative management. She has never had surgery before. She has a history of major depressive disorder and takes sertraline daily and ibuprofen occasionally for pain. Her mother died of breast cancer and her father died from a myocardial infarction. She has a brother who had an adverse reaction following anesthesia, but she does not know details of the event. In the operating room, the anesthesiologist administers isoflurane and succinylcholine. Two minutes later, the patient develops hypercarbia and hypertonicity of her bilateral upper and lower extremities. Her temperature is 103.7°F (39.8°C), blood pressure is 155/95 mmHg, pulse is 115/min, and respirations are 20/min. A medication with which of the following mechanisms of action is most strongly indicated for this patient?

A 71-year-old male is brought to the emergency room by his caretaker and presents with difficulty breathing, muscle rigidity in the face, neck, back and upper extremities, and profuse sweating. The intern notes a large wound on his head near the back of his right ear which his caretaker had bandaged up. The caretaker explains that the wound was the result of a fall while walking in his backyard. The intern performs a quick physical exam and observes increased reflexes. The patient was intubated to assist in his breathing and was given diazepam, metronidazole, and an immunoglobulin after the blood work came back. Which of the following neurotransmitters is affected in this patient?

You are currently employed as a clinical researcher working on clinical trials of a new drug to be used for the treatment of Parkinson's disease. Currently, you have already determined the safe clinical dose of the drug in a healthy patient. You are in the phase of drug development where the drug is studied in patients with the target disease to determine its efficacy. Which of the following phases is this new drug currently in?

A 36-year-old man presents to a psychiatrist for management of nicotine dependence. He has been a heavy smoker for the past 20 years. He has unsuccessfully attempted to quit smoking many times. He has seen multiple physicians for nicotine dependence. They prescribed nicotine replacement therapy and varenicline. He has also taken two antidepressants and participated in talk therapy. He asks the psychiatrist whether there are other alternatives. The psychiatrist explains that nicotine replacement therapy, non-nicotine pharmacotherapy, and talk therapy are the best options for the management of nicotine dependence. He tells the patient he can take a second-line medication for non-nicotine pharmacotherapy because the first-line medication failed. Which of the following medications would the psychiatrist most likely use to manage this patient’s nicotine dependence?

A neurophysiology expert is teaching his students the physiology of the neuromuscular junction. While describing the sequence of events that takes place at the neuromuscular junction, he mentions that as the action potential travels down the motor neuron, it causes depolarization of the presynaptic membrane. This results in the opening of voltage-gated calcium channels, which leads to an influx of calcium into the synapse of the motor neuron. Consequently, the cytosolic concentration of Ca2+ ions increases. Which of the following occurs at the neuromuscular junction as a result of this increase in cytosolic Ca2+?

A 26-year-old man is brought to the emergency department by his friends because of blurred vision and slurred speech for the past 6 hours. He had some difficulty swallowing his food during lunch and has weakness in both arms. Two weeks ago, he had an upper respiratory infection that resolved spontaneously. He lives independently and returned from his grandparents' farm 2 days ago. He commonly consumes canned vegetables and fruits. He is alert and oriented to person, place, and time. His temperature is 37°C (98.6°F), pulse is 88/min, respirations are 10/min and labored, and blood pressure is 110/70 mm Hg. Examination shows bilateral nystagmus and ptosis. The pupils are dilated and not reactive to light. Muscle strength of the facial muscles and bilateral upper extremities is decreased. Upper extremity deep tendon reflexes are 1+ bilaterally. Cardiopulmonary examination shows no abnormalities. Which of the following is the most likely cause for this patient's symptoms?