The nurse assumes care of a patient who has myasthenia gravis and notes that a dose of neostigmine (Prostigmin) due 1 hour prior was not given. The nurse will anticipate the patient to exhibit which symptoms?

A) It decreases the activity of norepinephrine receptor sites: Cholinergic agonists specifically act on acetylcholine receptors, not norepinephrine receptors. Norepinephrine is associated with the sympathetic nervous system and its receptors (alpha and beta), whereas cholinergic agonists affect the parasympathetic system through acetylcholine receptors.
B) It increases the activity of acetylcholine receptor sites: This is the correct answer. Cholinergic agonists work by stimulating acetylcholine receptors (both muscarinic and nicotinic), thereby enhancing the action of acetylcholine. This can lead to various effects such as decreased heart rate, increased digestion, and muscle contraction, as part of the parasympathetic nervous system response.
C) It decreases the activity of GABA receptor sites: GABA (gamma-aminobutyric acid) is an inhibitory neurotransmitter that acts on GABA receptors, not acetylcholine receptors. Cholinergic agonists have no direct effect on GABA receptor activity.
D) It increases the activity of dopamine receptor sites: Dopamine is a neurotransmitter primarily involved in the reward system, motor control, and mood regulation. Cholinergic agonists do not directly affect dopamine receptors. Instead, they target acetylcholine receptors, which are part of the parasympathetic nervous system.

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.