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) Beta 1-receptors:
Beta 1-receptors are primarily found in the heart, and their stimulation leads to increased heart rate and contractility. These receptors are not typically involved in vasoconstriction, pupil dilation, or piloerection.

B) Beta 2-receptors:
Beta 2-receptors are primarily located in smooth muscles such as the bronchi and blood vessels. Their stimulation causes smooth muscle relaxation, leading to bronchodilation and vasodilation. Beta 2-receptors are not responsible for the effects of vasoconstriction, piloerection, or pupil dilation described in the question, making this option incorrect.

C) Alpha 2-receptors:
Alpha 2-receptors are involved in the inhibition of norepinephrine release and play a role in regulating sympathetic tone. They are not primarily responsible for vasoconstriction or the other physiological responses listed in the question. Alpha 2-stimulation typically results in decreased sympathetic activity, not the effects described here.

D) Alpha 1-receptors:
Alpha 1-receptors are located on smooth muscle, including the blood vessels, and their stimulation results in vasoconstriction. They are also involved in other actions such as piloerection (hair standing on end), pupil dilation (mydriasis), and closure of the salivary sphincter. Additionally, they play a role in male sexual emission (ejaculation). The physiological responses described in the question—vasoconstriction, piloerection, pupil dilation, and male sexual emission—are all consistent with alpha 1-receptor stimulation.

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.