Autonomic Nervous System MCQs: 25 Questions with Answers

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Practice 25 Autonomic Nervous System MCQs with answers and short explanations. This set is designed for active recall and Physiology exam revision for healthcare students.

Try each question before opening the answer. The explanations are kept concise so you can revise the full set quickly.

25 Autonomic Nervous System MCQs with Answers

Q1. Which neurotransmitter is primarily released by sympathetic post‑ganglionic neurons?

  1. Acetylcholine
  2. Dopamine
  3. Norepinephrine
  4. Serotonin
Show answer & explanation

Correct answer: C. Norepinephrine

Sympathetic post‑ganglionic fibers release norepinephrine, which activates adrenergic receptors.

Q2. Which of the following is a characteristic of sympathetic post‑ganglionic fibers?

  1. Release acetylcholine
  2. Release norepinephrine
  3. Shorter axons
  4. Target only skeletal muscle
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Correct answer: B. Release norepinephrine

Most sympathetic post‑ganglionic neurons are adrenergic and release norepinephrine as their primary neurotransmitter (with exceptions like sweat glands which are cholinergic).

Q3. The baroreceptor reflex utilizes which autonomic components to regulate blood pressure?

  1. Only the sympathetic division
  2. Only the parasympathetic division
  3. Both sympathetic and parasympathetic divisions
  4. Neither autonomic division
Show answer & explanation

Correct answer: C. Both sympathetic and parasympathetic divisions

The baroreceptor reflex is a vital autonomic reflex that coordinates changes in both the sympathetic and parasympathetic divisions to regulate blood pressure and heart rate.

Q4. Which receptor is primarily responsible for mediating the parasympathetic effect on heart rate?

  1. β1‑adrenergic
  2. α1‑adrenergic
  3. M2 muscarinic
  4. M3 muscarinic
Show answer & explanation

Correct answer: C. M2 muscarinic

Parasympathetic vagal stimulation of the heart acts via M2 muscarinic receptors in the SA and AV nodes to decrease heart rate and conduction velocity.

Q5. Regarding the structural characteristics of sympathetic nervous system pathways:

  1. Pre‑ganglionic fibers are typically short and myelinated
  2. Post‑ganglionic fibers are typically short and myelinated
  3. Pre‑ganglionic fibers are long and unmyelinated
  4. Post‑ganglionic fibers are long and myelinated
Show answer & explanation

Correct answer: A. Pre‑ganglionic fibers are typically short and myelinated

In the sympathetic nervous system, pre‑ganglionic fibers typically originate in the thoracolumbar spinal cord, are short, and myelinated, whereas post‑ganglionic fibers are typically long and unmyelinated.

Q6. Which of the following conditions is primarily characterized by neurogenic orthostatic hypotension due to selective failure of the autonomic nervous system?

  1. Parkinson's disease
  2. Multiple system atrophy
  3. Pure autonomic failure
  4. Guillain‑Barré syndrome
Show answer & explanation

Correct answer: C. Pure autonomic failure

Pure autonomic failure is a sporadic, restricted neurodegenerative disorder characterized by primary failure of autonomic sympathetic vasoconstriction, leading to prominent orthostatic hypotension.

Q7. Which of the following best describes the origin of sympathetic pre‑ganglionic neurons?

  1. Sympathetic chain ganglia
  2. Target organs
  3. Thoracolumbar spinal cord
  4. Cranial nerve nuclei
Show answer & explanation

Correct answer: C. Thoracolumbar spinal cord

Sympathetic pre‑ganglionic fibers originate in the intermediolateral cell column of the thoracolumbar spinal cord (segments T1‑L2).

Q8. In the autonomic nervous system, which receptor type mediates vasoconstriction of vascular smooth muscle in response to sympathetic activation?

  1. α1‑adrenergic
  2. β2‑adrenergic
  3. Muscarinic M3
  4. Nicotinic N2
Show answer & explanation

Correct answer: A. α1‑adrenergic

α1‑adrenergic receptors are coupled to Gq proteins and mediate contraction of vascular smooth muscle, leading to vasoconstriction.

Q9. During a sudden drop in arterial blood pressure, which reflex pathway is primarily responsible for the rapid compensatory response?

  1. Chemoreceptor reflex
  2. Baroreceptor reflex
  3. Respiratory sinus arrhythmia
  4. Vestibular reflex
Show answer & explanation

Correct answer: B. Baroreceptor reflex

The arterial baroreceptor reflex detects changes in blood pressure, decreasing its firing rate during hypotension, which disinhibits sympathetic outflow and increases heart rate and contractility.

Q10. Which of the following nerves provides the primary parasympathetic pre‑ganglionic innervation to the heart and thoracic viscera?

  1. Facial nerve (CN VII)
  2. Glossopharyngeal nerve (CN IX)
  3. Vagus nerve (CN X)
  4. Hypoglossal nerve (CN XII)
Show answer & explanation

Correct answer: C. Vagus nerve (CN X)

The vagus nerve (CN X) provides the principal parasympathetic pre-ganglionic supply to the heart, where it acts to decrease heart rate.

Q11. Post‑ganglionic sympathetic fibers innervating most sweat glands primarily release which neurotransmitter to stimulate secretion?

  1. Acetylcholine
  2. Norepinephrine
  3. Epinephrine
  4. Dopamine
Show answer & explanation

Correct answer: A. Acetylcholine

Although most sympathetic post-ganglionic neurons are noradrenergic, those innervating eccrine sweat glands are an exception and release acetylcholine acting on muscarinic receptors.

Q12. Which of the following is a primary function of the parasympathetic division of the autonomic nervous system?

  1. Increase heart rate
  2. Stimulate sweat glands
  3. Promote digestion
  4. Dilate pupils
Show answer & explanation

Correct answer: C. Promote digestion

The parasympathetic system promotes rest‑and‑digest activities such as stimulating digestion and slowing heart rate.

Q13. In the sympathetic division, the pre‑ganglionic neurons originate from which spinal cord segments?

  1. Cervical
  2. Thoracolumbar
  3. Lumbar
  4. Sacral
Show answer & explanation

Correct answer: B. Thoracolumbar

Sympathetic pre‑ganglionic neurons arise from the thoracolumbar (T1–L2) segments of the spinal cord.

Q14. Which neurotransmitter is primarily released by sympathetic post‑ganglionic fibers that innervate most vascular smooth muscle?

  1. Acetylcholine
  2. Norepinephrine
  3. Dopamine
  4. Serotonin
Show answer & explanation

Correct answer: B. Norepinephrine

Sympathetic post‑ganglionic fibers to most blood vessels release norepinephrine, causing vasoconstriction via alpha-1 adrenergic receptors.

Q15. Which of the following structures contains the cell bodies of sympathetic pre‑ganglionic neurons?

  1. Intermediolateral cell column
  2. Dorsal root ganglia
  3. Ventral horn
  4. Medulla oblongata
Show answer & explanation

Correct answer: A. Intermediolateral cell column

The intermediolateral cell column (IML) of the thoracolumbar spinal cord houses the cell bodies of sympathetic pre‑ganglionic neurons.

Q16. Which of the following is a classic clinical manifestation of autonomic dysfunction in neurodegenerative conditions like Parkinson's disease?

  1. Hyperhidrosis
  2. Orthostatic hypotension
  3. Fixed tachycardia at rest
  4. Exercise-induced hypertension
Show answer & explanation

Correct answer: B. Orthostatic hypotension

Orthostatic hypotension results from impaired sympathetic vasomotor reflexes and is frequently seen in Parkinson's disease due to autonomic failure.

Q17. Which of the following is a characteristic of parasympathetic preganglionic fibers?

  1. Long axons that extend to terminal ganglia near or within target organs
  2. Short axons that synapse in ganglia close to the spinal cord
  3. Release norepinephrine at the target organ
  4. Originate from thoracolumbar spinal segments
Show answer & explanation

Correct answer: A. Long axons that extend to terminal ganglia near or within target organs

Parasympathetic preganglionic neurons typically have long axons that travel considerable distances to terminal or intramural ganglia located near or within the walls of target organs.

Q18. What is the primary neurotransmitter released by sympathetic preganglionic neurons?

  1. Acetylcholine
  2. Norepinephrine
  3. Dopamine
  4. Serotonin
Show answer & explanation

Correct answer: A. Acetylcholine

Sympathetic preganglionic neurons are cholinergic and release acetylcholine, which acts on nicotinic receptors on postganglionic neurons.

Q19. Activation of parasympathetic input to the heart primarily produces which of the following cardiac effects via muscarinic receptors?

  1. Increased heart rate (tachycardia)
  2. Decreased heart rate (bradycardia)
  3. Increased ventricular contractility
  4. Enhanced AV nodal conduction velocity
Show answer & explanation

Correct answer: B. Decreased heart rate (bradycardia)

Parasympathetic (vagal) stimulation releases acetylcholine, which acts on M2 muscarinic receptors in the heart to decrease heart rate (negative chronotropy) and slow AV nodal conduction.

Q20. Where do sympathetic preganglionic neurons originate within the central nervous system?

  1. Craniosacral regions of the spinal cord
  2. Thoracolumbar regions of the spinal cord
  3. Sensory cortex of the cerebrum
  4. Cerebellar deep nuclei
Show answer & explanation

Correct answer: B. Thoracolumbar regions of the spinal cord

Sympathetic preganglionic neurons originate from the thoracolumbar division (segments T1-L2/L3) of the spinal cord, whereas parasympathetic neurons originate from the craniosacral regions.

Q21. Which of the following is a major physiological effect of sympathetic nervous system stimulation on the respiratory system?

  1. Bronchoconstriction
  2. Bronchodilation
  3. Increased bronchial mucus secretion
  4. Pulmonary vasoconstriction leading to airway collapse
Show answer & explanation

Correct answer: B. Bronchodilation

Sympathetic activation stimulates beta-2 adrenergic receptors located on bronchial smooth muscle, resulting in relaxation of the smooth muscle and bronchodilation.

Q22. Where are the cell bodies of sympathetic pre‑ganglionic neurons located?

  1. Thoracolumbar spinal cord
  2. Cervical spinal cord
  3. Sacral spinal cord
  4. Brainstem
Show answer & explanation

Correct answer: A. Thoracolumbar spinal cord

Sympathetic pre‑ganglionic neurons reside in the intermediolateral cell column of the thoracolumbar spinal cord (T1–L2).

Q23. When arterial pressure falls, which reflex increases sympathetic tone to restore blood pressure?

  1. Baroreceptor reflex
  2. Chemoreceptor reflex
  3. Vestibular reflex
  4. Ocular reflex
Show answer & explanation

Correct answer: A. Baroreceptor reflex

The baroreceptor reflex detects decreased arterial pressure and triggers sympathetic activation to raise heart rate and peripheral resistance.

Q24. Acetylcholine released by parasympathetic fibers at the sinoatrial node primarily causes what change in cardiac conduction?

  1. Increase heart rate
  2. Decrease heart rate
  3. Increase conduction velocity
  4. Decrease conduction velocity
Show answer & explanation

Correct answer: B. Decrease heart rate

Parasympathetic acetylcholine binds M2 muscarinic receptors at the SA node, slowing the pacemaker activity and reducing heart rate.

Q25. Where are the cell bodies of sympathetic post‑ganglionic neurons located?

  1. Sympathetic chain ganglia
  2. Intermediolateral cell column
  3. Cranial nerve nuclei
  4. Spinal cord dorsal horn
Show answer & explanation

Correct answer: A. Sympathetic chain ganglia

Sympathetic post‑ganglionic neuron cell bodies are situated in the sympathetic chain (paravertebral) ganglia adjacent to the spinal cord.

How to Use This MCQ Set

Attempt all 25 questions once without checking the answers. Review only the questions you missed, then repeat those questions in your next revision round. This turns the page into a reusable practice set rather than a one-time read.

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