Which of the following is NOT a function of sympathetic nervous system?

JSSH Staff Nurse - 2019

Applied Physiology

Easy

Appeared in: JSSH Staff Nurse - 2019

Explanation

"Rest and digest" is the key phrase used to describe the primary role of the Parasympathetic Nervous System (PNS).
The PNS is responsible for conserving energy and overseeing routine, non-emergency functions like digestion and waste elimination when the body is at rest.
The functions of the PNS are generally antagonistic (opposite) to the functions of the Sympathetic Nervous System (SNS).
Therefore, "Rest and digest" is not a function of the sympathetic nervous system.

Option A: Dilation of the pupils (mydriasis) is a classic sympathetic response.
Option C: "Fight and flight" is the common term that summarizes the overall purpose of the sympathetic nervous system.
Option D: Tachycardia, or an increased heart rate, is a key action of the sympathetic nervous system.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Functions of the Autonomic Nervous System (Sympathetic vs. Parasympathetic) as background academic context rather than a clinical decision trigger.
Understanding the opposing actions of the sympathetic and parasympathetic systems is fundamental for predicting the effects and side effects of many medications, such as beta-blockers (which block sympathetic effects) and anticholinergics (which block parasympathetic effects).
In a clinical setting, a nurse can assess autonomic function by observing for signs like an unexpectedly high heart rate (tachycardia) at rest, which might indicate an overactive sympathetic system or a problem with the parasympathetic system.
What if a patient is given an anticholinergic drug like atropine? The answer is that it would block the 'rest and digest' (parasympathetic) system, leading to unopposed sympathetic effects like tachycardia, pupil dilation, and dry mouth.

How to Approach the Question

First, identify the negative keyword 'NOT' in the question stem. This signals that you must find the option that is an exception or does not fit with the others.
Recall the primary function of the sympathetic nervous system. The key phrase to remember is 'fight or flight'.
Systematically evaluate each option to see if it aligns with the 'fight or flight' response.
Option A (Dilation of pupils), Option C (Fight and flight), and Option D (Tachycardia) are all actions that prepare the body for an emergency.
Option B (Rest and digest) is the opposite of preparing for an emergency; it relates to bodily functions during a calm state.
Conclude that 'Rest and digest' is the function that does NOT belong to the sympathetic nervous system.

Concept Tested & Keywords

Concept Tested: Functions of the Autonomic Nervous System (Sympathetic vs. Parasympathetic)
Stem keywords: sympathetic nervous system, function
Lead-in keywords: NOT
Negative lead-in flag: The question uses a negative keyword 'NOT', asking to identify the option that is an exception.

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