Which division of the nervous system initiates a response known as fight or flight?

RRB Staff Nurse Delhi-2015

Applied Physiology

Easy

Appeared in: RRB Staff Nurse Delhi-2015

Explanation

The sympathetic nervous system is a division of the autonomic nervous system that becomes highly active during stressful situations.
It initiates the 'fight or flight' response, a cascade of physiological changes that prepare the body to either confront or flee from a perceived threat.
Key effects include an increased heart rate, dilation of the bronchioles for better oxygenation, and mobilization of glucose for energy.
The primary neurotransmitter responsible for these actions is norepinephrine.

Option A: The parasympathetic nervous system is responsible for the 'rest and digest' response, which has effects opposite to the 'fight or flight' response, such as slowing the heart rate and stimulating digestion.
Option C: The somatic nervous system controls voluntary movements of skeletal muscles, such as walking or picking up an object. It is not involved in the involuntary, automatic responses of the internal organs seen in the fight or flight response.
Option D: This option is incorrect because a correct answer, the sympathetic nervous system, is provided in the options.

Visual 1: Diagram - A comparative chart showing the opposing effects of the sympathetic and parasympathetic nervous systems on various organs like the heart, lungs, pupils, and digestive tract. This helps visualize the 'fight or flight' vs. 'rest and digest' functions.
Visual 2: Flowchart - A flowchart illustrating the sequence of events during the fight or flight response, starting from a stress stimulus, leading to sympathetic activation, release of norepinephrine/epinephrine, and the resulting physiological changes.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Divisions and Functions of the Autonomic Nervous System as background academic context rather than a clinical decision trigger.
Understanding the sympathetic response is crucial for nurses to recognize and manage a patient's physiological reaction to stress, pain, or trauma.
Many emergency medications, such as epinephrine (a sympathomimetic), work by mimicking the effects of the sympathetic nervous system to treat conditions like cardiac arrest and anaphylaxis.
Conversely, drugs like beta-blockers (sympatholytics) are used to block sympathetic effects, for instance, to lower blood pressure and heart rate in patients with hypertension or heart conditions.

How to Approach the Question

First, identify the key phrase in the question: 'fight or flight'. This is a classic physiological concept.
Recall the major divisions of the nervous system. The peripheral nervous system is divided into the somatic (voluntary) and autonomic (involuntary) systems.
Remember that the autonomic nervous system has two main branches: the sympathetic and the parasympathetic.
Associate the sympathetic division with 'stress' and 'action' ('fight or flight').
Associate the parasympathetic division with 'peace' and 'relaxation' ('rest and digest').
Based on this association, select the sympathetic nervous system as the initiator of the 'fight or flight' response and eliminate the other options.

Concept Tested & Keywords

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