Case Scenario:
Derek Zoolander is a 32-year-old fashion model for a world famous modeling agency. Over the last 8 months, he experienced "strange" symptoms. He had severe eyestrain when he modeled for longer than 15 minutes. He became tired when he did common tasks, such as eating, and he had extreme fatigue on the job. Despite his strong work ethic, Derek had to excuse himself from several photo shoots because he simply could not pose. Derek is not a complainer, but he began to worry about these vague symptoms. His physician suspected myasthenia gravis. While awaiting the results of a serum antibody test, the physician initiated a trial of an acetylcholinesterase inhibitor. Derek immediately felt better while taking the drug; his strength returned and he could work normally. Meanwhile, the results of the antibody test were positive, confirming the diagnosis of myasthenia gravis.
1. What are the steps of neuromuscular transmission?
2. What step of neuromuscular transmission is blocked by myasthenia gravis (review pages 86-87 in Guyton and Hall)?
3. Explain why muscle weakness occurs in myasthenia gravis.
4. How does curare compare to myasthenia gravis in action?