The nurse is preparing to care for a patient who has myasthenia gravis. The nurse will be alert to symptoms affecting which body system in this patient?

A) Central nervous system (CNS), memory, and cognition: Myasthenia gravis (MG) primarily affects the neuromuscular junction, causing muscle weakness, not directly the central nervous system. While cognitive function may be affected in some patients due to fatigue or medication side effects, it is not the main system affected by MG. B) Cardiovascular system and postural muscles: Myasthenia gravis primarily affects skeletal muscles, especially those responsible for voluntary movements like facial muscles, swallowing, and respiratory muscles. While MG can lead to general weakness, it does not typically affect the cardiovascular system directly. C) Respiratory system and facial muscles: This is the correct answer. Myasthenia gravis primarily affects the voluntary muscles, particularly those controlling eye movements, facial expressions, swallowing, and breathing. The respiratory system is vulnerable due to weakness of the diaphragm and intercostal muscles, which can lead to respiratory distress in severe cases. Facial muscles are commonly affected, leading to symptoms like ptosis (drooping eyelids) and difficulty smiling or speaking. D) Gastrointestinal system (GI) and lower extremity muscles: Although myasthenia gravis can cause generalized muscle weakness, it is not typically associated with the gastrointestinal system. The primary impact is on the voluntary muscles, such as those in the face, throat, and respiratory system. Lower extremity muscles can be affected, but the respiratory and facial muscles are more commonly involved.