Which of the following is an autonomic reflex?

BSF Staff Nurse - 2015

Applied Physiology

Medium

Appeared in: BSF Staff Nurse - 2015

Explanation

The mass reflex is a pathological reflex involving a massive, uncoordinated discharge of the autonomic nervous system.
It is a key feature of autonomic dysreflexia, a condition often seen in patients with spinal cord injuries above the T6 level.
This reflex results in widespread visceral effects such as hypertension, sweating, flushing, and involuntary bladder or bowel emptying, all of which are functions controlled by the autonomic nervous system.
Unlike somatic reflexes that target skeletal muscles, the mass reflex targets smooth muscles (in blood vessels and viscera) and glands.

Option A: The stumble reflex is a somatic reflex. It involves the contraction of skeletal muscles in the limbs to maintain balance and adjust gait, which is a function of the somatic nervous system.
Option B: The galloping reflex is a complex somatic motor pattern. It describes a specific, coordinated sequence of skeletal muscle contractions for locomotion, not an involuntary response of internal organs.
Option D: The plantar reflex is a classic somatic reflex. It is classified as a superficial (cutaneous) reflex where the response is the contraction of skeletal muscles in the toes.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of reflexes into somatic and autonomic as background academic context rather than a clinical decision trigger.
Recognizing the mass reflex is critical for nurses, as it signals autonomic dysreflexia in patients with spinal cord injuries (most common with injuries at T6 or above). This is a medical emergency that can lead to stroke or seizure if not treated promptly.
Immediate nursing interventions for autonomic dysreflexia include sitting the patient upright to lower blood pressure, loosening any tight clothing or constrictive devices, and identifying and removing the noxious stimulus (e.g., checking for a full bladder, kinked catheter, or bowel impaction).
What if? If a patient with a known spinal cord injury at C7 suddenly complains of a pounding headache and is sweating profusely, the nurse's first action should be to check the patient's blood pressure, as these are classic signs of autonomic dysreflexia.

How to Approach the Question

First, understand the core question. It asks to identify an 'autonomic reflex' from the given options.
Define the key term: An autonomic reflex controls visceral functions (internal organs, glands, blood vessels), while a somatic reflex controls skeletal muscles.
Evaluate each option against this definition.
Consider 'Stumble reflex' and 'Galloping reflex'. Both relate to body movement and locomotion, which involve skeletal muscles. Therefore, they are somatic.
Consider 'Plantar reflex'. This involves stroking the foot and observing toe movement. The toes are moved by skeletal muscles. This is a somatic reflex.
Consider 'Mass reflex'. This involves widespread systemic responses like high blood pressure, sweating, and bladder contraction. These are functions of internal organs and glands, controlled by the autonomic nervous system. This makes it the correct answer.

Concept Tested & Keywords

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E6 Physiology Essentials Sembulingam 10e Part 3 p. 69-71

E6 Medicine Harrison 22e Part 2 p. 1285-1287