A patient is admitted to the emergency department in shock. Isoproterenol (Isuprel) is admitted. What would the nurse expect the effect of this drug would be?

A) Increased calcium: Sympathetic activation typically does not cause a direct increase in calcium levels. Calcium levels are more influenced by factors like parathyroid hormone (PTH) and vitamin D, or conditions such as bone disease or renal issues. Although some stress responses can lead to changes in calcium metabolism, an increase in calcium is not a typical response to sympathetic activation.

B) Decreased sodium: While sodium imbalances can occur in various conditions, the sympathetic nervous system does not directly cause a decrease in sodium. The body's handling of sodium is more influenced by factors like kidney function and the renin-angiotensin-aldosterone system. Stress-related changes in sodium levels are less likely to cause a significant decrease in sodium, making this an unlikely focus in monitoring.

C) Decreased potassium: During stress, the body releases catecholamines (like epinephrine) as part of the sympathetic nervous response, which stimulates the movement of potassium into cells. This can result in a transient decrease in serum potassium levels (hypokalemia). Monitoring for decreased potassium is important, as low potassium can lead to cardiac arrhythmias and muscle weakness, which are particularly concerning after surgery or trauma.

D) Increased chloride: Chloride is typically maintained in balance with sodium, and while it may shift in certain conditions, sympathetic activation does not directly lead to increased chloride levels. Most chloride imbalances are secondary to changes in sodium, acid-base disturbances, or kidney function. Therefore, an increase in chloride is less likely in this scenario.

A) The cell body of the first motor neuron that lies in the brain stem:
This option refers to the somatic nervous system, which controls voluntary muscle movements. In response to a stressful or fearful situation, like the one described, the sympathetic nervous system is activated, not the somatic motor pathways. This is more related to voluntary motor control rather than the autonomic response to stress.

B) Reflex circuitry produced by the ANS reflex:
The autonomic nervous system (ANS) is involved in regulating involuntary functions like heart rate, blood pressure, and digestion. However, the "racing heart" response described here is primarily triggered by the sympathetic division of the ANS due to a stressor, such as seeing the cat. The reflex itself is part of a larger autonomic reaction, but the direct cause of the increased heart rate is the secretion of neurotransmitters.

C) Parasympathetic effect on the vagus nerve:
The parasympathetic nervous system (PNS) generally works to counteract the "fight or flight" response, promoting a relaxed state and slowing the heart rate. The vagus nerve is the primary parasympathetic pathway involved in decreasing heart rate. However, during stress or a fear response, the parasympathetic system is overridden by the sympathetic system, which increases heart rate, making this option incorrect.

D) Secretion of the sympathetic neurotransmitters produced in the adrenal medulla:
When a person experiences a stressor, like the sudden appearance of a cat, the sympathetic nervous system is activated, triggering the release of neurotransmitters like norepinephrine from sympathetic nerve endings and epinephrine (adrenaline) from the adrenal medulla. These chemicals act on the heart, causing it to race in response to the perceived threat.