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

JODHPUR AIIMS SNO-2018

Applied Physiology

Easy

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

'Rest and digest' is the phrase used to describe the primary functions of the parasympathetic nervous system.
The parasympathetic system is responsible for conserving energy, slowing the heart rate, and stimulating activities like digestion and urination.
The sympathetic and parasympathetic systems are physiological antagonists, meaning they generally have opposing effects on the same organs.

Option A: This is a primary function of the sympathetic nervous system. During a 'fight or flight' response, the heart rate is accelerated to increase cardiac output and deliver more oxygenated blood to the muscles and vital organs.
Option C: This is a key function of the sympathetic nervous system. It causes vasoconstriction (narrowing of blood vessels), which increases blood pressure to ensure adequate perfusion of vital organs during stress.
Option D: This is the classic term used to summarize the overall purpose of the sympathetic nervous system. It prepares the body to either confront or flee from a perceived threat.

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.
Nurses must differentiate between sympathetic and parasympathetic responses to accurately assess a patient's condition. For example, tachycardia and hypertension could indicate stress, pain, or anxiety (sympathetic activation).
Many medications, such as beta-blockers (which block sympathetic effects on the heart) or anticholinergics (which block parasympathetic effects), directly target the autonomic nervous system. Understanding this helps in predicting drug effects and side effects.
What if a patient is on a beta-blocker medication? A patient on a beta-blocker might not exhibit the expected tachycardia in response to a stressor like blood loss or infection, as the drug blunts the sympathetic response. Nurses must look for other signs of distress, such as changes in mental status or urine output.

How to Approach the Question

First, identify the keyword 'not'. This indicates you are looking for the option that is an exception or does not fit.
Next, recall the primary role of the sympathetic nervous system. The key phrase is 'fight or flight'.
Evaluate each option against this 'fight or flight' concept.
Does increasing heart rate fit 'fight or flight'? Yes, you need more blood flow.
Does increasing blood pressure fit 'fight or flight'? Yes, to perfuse muscles and organs.
Does 'rest and digest' fit 'fight or flight'? No, these are opposite activities. Digestion is not a priority in an emergency.

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 asks to identify the function that does NOT belong to the sympathetic nervous system.

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