Reflex activity MCQs With Answer

Reflex activity MCQs With Answer offers B.Pharm students a focused, exam-oriented review of reflex physiology and pharmacology. This SEO-friendly introduction covers reflex arc components, afferent and efferent pathways, monosynaptic and polysynaptic reflexes, autonomic reflexes (baroreceptor, cough, gag, pupillary), and drug effects on reflexes. Emphasis on clinical relevance, neurotransmitters, and drug interactions helps students link neurophysiology to therapeutics and toxicity. Ideal for quick revision, practical exams, and competitive tests, these targeted questions strengthen understanding of reflex mechanisms and pharmacological modulation. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which structure is NOT a component of the basic reflex arc?

• Sensory receptor
• Afferent neuron
• Central integration center
• Basal ganglia

Correct Answer: Basal ganglia

Q2. In a monosynaptic stretch reflex, which afferent fiber type carries the primary signal from the muscle spindle?

• Type Ib
• Type II
• Type Ia
• Type III

Correct Answer: Type Ia

Q3. Golgi tendon organs primarily respond to which mechanical parameter?

• Muscle length
• Muscle tension (force)
• Muscle velocity
• Muscle temperature

Correct Answer: Muscle tension (force)

Q4. Which neurotransmitter is released at the neuromuscular junction causing muscle contraction?

• Norepinephrine
• Acetylcholine
• GABA
• Glutamate

Correct Answer: Acetylcholine

Q5. Baroreceptors that mediate the carotid sinus reflex send afferents via which cranial nerve?

• Vagus nerve (CN X)
• Glossopharyngeal nerve (CN IX)
• Trigeminal nerve (CN V)
• Facial nerve (CN VII)

Correct Answer: Glossopharyngeal nerve (CN IX)

Q6. Activation of the baroreceptor reflex by increased arterial pressure produces which immediate cardiac response?

• Tachycardia
• Bradycardia
• Increased contractility
• Peripheral vasoconstriction

Correct Answer: Bradycardia

Q7. The pupillary light reflex afferent limb is carried by which nerve?

• Oculomotor nerve (CN III)
• Optic nerve (CN II)
• Trochlear nerve (CN IV)
• Facial nerve (CN VII)

Correct Answer: Optic nerve (CN II)

Q8. Which nucleus provides the parasympathetic efferent for the pupillary light reflex?

• Edinger-Westphal nucleus
• Dorsal motor nucleus of vagus
• Nucleus ambiguus
• Solitary nucleus

Correct Answer: Edinger-Westphal nucleus

Q9. The cough reflex afferent fibers predominantly travel in which nerve?

• Glossopharyngeal nerve (CN IX)
• Vagus nerve (CN X)
• Accessory nerve (CN XI)
• Hypoglossal nerve (CN XII)

Correct Answer: Vagus nerve (CN X)

Q10. Which of the following best describes a polysynaptic reflex?

• Single synapse between afferent and efferent neurons
• Involves one interneuron or more between afferent and efferent neurons
• No synapses in the central nervous system
• Only occurs in cranial nerves

Correct Answer: Involves one interneuron or more between afferent and efferent neurons

Q11. Reciprocal inhibition during a stretch reflex involves inhibition of which cells?

• Alpha motor neurons of antagonist muscles
• Gamma motor neurons of agonist muscles
• Renshaw cells of agonist muscles
• Corticospinal neurons

Correct Answer: Alpha motor neurons of antagonist muscles

Q12. Gamma motor neurons primarily regulate reflex sensitivity by innervating what?

• Golgi tendon organs
• Extrafusal muscle fibers
• Intrafusal muscle fibers (muscle spindles)
• Sensory endings of Ia fibers

Correct Answer: Intrafusal muscle fibers (muscle spindles)

Q13. Which cell type mediates recurrent inhibition of motor neurons in the spinal cord?

• Renshaw cells
• Purkinje cells
• Intercalated cells
• Microglia

Correct Answer: Renshaw cells

Q14. Autogenic inhibition is mediated by which afferent fibers?

• Ia fibers from muscle spindles
• Ib fibers from Golgi tendon organs
• Type III nociceptors
• A-beta cutaneous afferents

Correct Answer: Ib fibers from Golgi tendon organs

Q15. Which reflex would be used clinically to assess integrity of spinal segment L4-L5?

• Achilles (S1-S2) reflex
• Patellar (knee jerk) reflex
• Biceps reflex (C5-C6)
• Triceps reflex (C7-C8)

Correct Answer: Patellar (knee jerk) reflex

Q16. Damage to upper motor neurons typically produces which reflex change?

• Hyporeflexia
• Areflexia initially then hyperreflexia later
• Only peripheral neuropathy signs
• No change in reflexes

Correct Answer: Areflexia initially then hyperreflexia later

Q17. The Babinski sign indicates lesion of which pathway?

• Corticospinal (pyramidal) tract
• Spinothalamic tract
• Dorsal column-medial lemniscus
• Basal ganglia circuits

Correct Answer: Corticospinal (pyramidal) tract

Q18. Which reflex is principally suppressed by benzodiazepines and other GABAergic drugs?

• Polysynaptic withdrawal reflex
• Monosynaptic stretch reflex amplitude
• Baroreceptor reflex sensitivity
• Pupillary light reflex

Correct Answer: Polysynaptic withdrawal reflex

Q19. Which drug blocks muscarinic receptors and thus abolishes vagally mediated reflex bradycardia?

• Propranolol
• Atropine
• Phenylephrine
• Neostigmine

Correct Answer: Atropine

Q20. Phenylephrine infusion raises arterial pressure and reflexively causes what change in heart rate?

• Reflex tachycardia
• Reflex bradycardia
• No change in heart rate
• Arrhythmogenic tachycardia

Correct Answer: Reflex bradycardia

Q21. The gag reflex afferent limb is mediated by which cranial nerve?

• Vagus nerve (CN X)
• Glossopharyngeal nerve (CN IX)
• Trigeminal nerve (CN V)
• Accessory nerve (CN XI)

Correct Answer: Glossopharyngeal nerve (CN IX)

Q22. Which efferent nerve executes the motor component of the gag reflex?

• Glossopharyngeal nerve (CN IX)
• Vagus nerve (CN X)
• Facial nerve (CN VII)
• Hypoglossal nerve (CN XII)

Correct Answer: Vagus nerve (CN X)

Q23. Which reflex is reduced by opioid administration and used as a clinical sign of opioid effect?

• Pupillary light reflex
• Cough reflex
• Knee jerk reflex
• Baroreceptor reflex

Correct Answer: Cough reflex

Q24. The H-reflex is most analogous to which physiological reflex?

• Withdrawal (flexor) reflex
• Monosynaptic stretch reflex
• Pupillary light reflex
• Gag reflex

Correct Answer: Monosynaptic stretch reflex

Q25. Which spinal interneuron population mediates reciprocal inhibition?

• Renshaw cells
• Ia inhibitory interneurons
• Ib excitatory interneurons
• Spongioblasts

Correct Answer: Ia inhibitory interneurons

Q26. Clasp-knife phenomenon in spastic limbs is attributed to exaggerated which reflex?

• Stretch reflex (monosynaptic)
• Golgi tendon organ-mediated inhibitory reflex
• Withdrawal reflex
• Crossed extensor reflex

Correct Answer: Golgi tendon organ-mediated inhibitory reflex

Q27. Which reflex helps terminate inspiration during lung inflation?

• Hering–Breuer reflex
• Cough reflex
• Withdrawal reflex

Correct Answer: Hering–Breuer reflex

Q28. Which receptor type in carotid bodies primarily senses hypoxia to trigger chemoreceptor reflexes?

• Mechanoreceptors
• Type I glomus cells (chemoreceptors)
• Thermoreceptors
• Baroreceptors

Correct Answer: Type I glomus cells (chemoreceptors)

Q29. Which descending neurotransmitter systems modulate spinal reflex excitability?

• Serotonergic and noradrenergic pathways
• Cholinergic only
• Dopaminergic exclusively
• Histaminergic only

Correct Answer: Serotonergic and noradrenergic pathways

Q30. Which sign indicates loss of inhibitory descending control on spinal reflexes?

• Hypotonia
• Hyperreflexia and spasticity
• Flaccid paralysis only
• Peripheral neuropathy

Correct Answer: Hyperreflexia and spasticity

Q31. Non-depolarizing neuromuscular blockers (e.g., pancuronium) affect reflex testing by:

• Increasing reflex amplitude
• Abolishing muscle responses to reflexes by blocking NMJ
• Enhancing spinal interneuron activity
• Selective blockade of Ia afferents

Correct Answer: Abolishing muscle responses to reflexes by blocking NMJ

Q32. Depolarizing blocker succinylcholine initially causes muscle fasciculations because it:

• Stimulates nicotinic receptors causing transient depolarization
• Blocks acetylcholinesterase
• Inhibits GABA receptors
• Activates muscarinic receptors

Correct Answer: Stimulates nicotinic receptors causing transient depolarization

Q33. The oculocardiac reflex results in bradycardia when which nerve is stimulated?

• Trigeminal nerve afferent leading to vagal efferent
• Facial nerve afferent leading to sympathetic efferent
• Optic nerve afferent leading to motor efferent
• Trochlear nerve afferent leading to somatic efferent

Correct Answer: Trigeminal nerve afferent leading to vagal efferent

Q34. Which clinical reflex assesses trigeminal sensory and facial motor pathways?

• Corneal reflex
• Patellar reflex
• Pupillary light reflex
• Achilles reflex

Correct Answer: Corneal reflex

Q35. Which ion channel blockade would most directly reduce synaptic transmission in central reflex arcs?

• Sodium channel blockers
• Calcium channel enhancers
• Potassium channel openers
• Chloride channel blockers

Correct Answer: Sodium channel blockers

Q36. Which pharmacologic agent is expected to blunt the baroreceptor reflex when given systemically?

• Atropine
• Propranolol
• Phenylephrine
• Acetylcholine

Correct Answer: Propranolol

Q37. Horner’s syndrome arises from interruption of which pathway affecting pupillary reflex?

• Parasympathetic pupillary constrictor pathway
• Sympathetic pupillary dilator pathway
• Optic afferent limb
• Facial motor limb

Correct Answer: Sympathetic pupillary dilator pathway

Q38. Which reflex loop is primarily involved in posture and antigravity muscle tone during standing?

• Vestibulospinal reflexes
• Pupillary light reflex
• Cough reflex
• Jaw jerk reflex

Correct Answer: Vestibulospinal reflexes

Q39. Which reflex is tested by tapping the masseter tendon and assesses trigeminal motor nucleus?

• Jaw jerk reflex
• Corneal reflex
• Gag reflex
• H-reflex

Correct Answer: Jaw jerk reflex

Q40. Which clinical change is characteristic of spinal shock in the acute phase?

• Hyperreflexia from onset
• Loss of all reflexes below lesion level
• Immediate spasticity
• Enhanced autonomic reflexes

Correct Answer: Loss of all reflexes below lesion level

Q41. Which neurotransmitter predominantly mediates fast excitatory synaptic transmission in spinal reflex interneurons?

• GABA
• Glycine
• Glutamate
• Acetylcholine

Correct Answer: Glutamate

Q42. Which reflex is a protective polysynaptic response to painful stimulus?

• Stretch reflex
• Withdrawal (flexor) reflex
• Golgi tendon reflex
• Pupillary light reflex

Correct Answer: Withdrawal (flexor) reflex

Q43. Which drug class can increase spinal reflex excitability and worsen spasticity?

• Benzodiazepines
• GABA agonists
• Tricyclic antidepressants (by reducing inhibitory tone)
• Muscle relaxants

Correct Answer: Tricyclic antidepressants (by reducing inhibitory tone)

Q44. Which reflex is commonly used to evaluate brainstem function in comatose patients?

• Pupillary light reflex
• Patellar reflex
• Achilles reflex
• H-reflex

Correct Answer: Pupillary light reflex

Q45. Which receptor subtype mediates fast excitatory transmission at the motor endplate?

• Muscarinic M2 receptors
• Nicotinic acetylcholine receptors (Nm type)
• GABA-A receptors
• NMDA receptors in CNS only

Correct Answer: Nicotinic acetylcholine receptors (Nm type)

Q46. Autonomic dysreflexia seen in high spinal cord injury is characterized by:

• Severe hypertension with reflex bradycardia
• Hypotension with tachycardia
• Hyperthermia and tachypnea
• Loss of all autonomic reflexes without blood pressure change

Correct Answer: Severe hypertension with reflex bradycardia

Q47. Which pharmacological agent can enhance spinal inhibitory glycinergic transmission and reduce reflex hyperexcitability?

• Strychnine
• Baclofen (GABAB agonist)
• Tizanidine (alpha-2 agonist)
• Gabapentin

Correct Answer: Tizanidine (alpha-2 agonist)

Q48. Which test is most appropriate to assess conduction of large myelinated Ia fibers?

• Thermal sensory testing
• Tendon reflex (e.g., Achilles or patellar tap)
• Pain threshold testing
• Electrochemical microdialysis

Correct Answer: Tendon reflex (e.g., Achilles or patellar tap)

Q49. Which nucleus integrates visceral afferents and helps mediate autonomic reflexes such as baroreflex?

• Red nucleus
• Nucleus tractus solitarius (NTS)
• Substantia nigra
• Ventrolateral thalamus

Correct Answer: Nucleus tractus solitarius (NTS)

Q50. Why are reflex assessments important in pharmacology and toxicology studies?

• They are irrelevant to drug safety
• They help detect neural drug effects, neuromuscular blockade, and central depressant actions
• They only measure liver toxicity
• They exclusively evaluate renal function

Correct Answer: They help detect neural drug effects, neuromuscular blockade, and central depressant actions

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

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