Understanding the structure and function of the sympathetic nervous system is essential for B. Pharm students learning pharmacology, therapeutics and drug action. This pathway, originating in the thoracolumbar spinal cord, uses cholinergic preganglionic neurons and mainly adrenergic postganglionic neurons to mediate the fight-or-flight response. Key elements include sympathetic chain and prevertebral ganglia, adrenal medulla secretion of epinephrine, adrenergic receptor subtypes (α1, α2, β1, β2, β3), neurotransmitter metabolism (NET, MAO, COMT), and varicosity-based synaptic transmission. Pharmacologic targeting of these components underlies treatments for asthma, hypertension, shock and urinary disorders. Clear understanding of anatomy, receptor signaling and drug effects enhances clinical reasoning. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which spinal segments give rise to the sympathetic outflow?
- Brainstem (cranial nerves)
- Sacral (S2-S4)
- Thoracolumbar (T1-L2)
- Cervical (C1-C8)
Correct Answer: Thoracolumbar (T1-L2)
Q2. What is the primary neurotransmitter released by sympathetic preganglionic neurons, and its receptor type on the ganglion?
- Norepinephrine acting on adrenergic receptors
- Acetylcholine acting on nicotinic receptors
- Acetylcholine acting on muscarinic receptors
- Dopamine acting on D1 receptors
Correct Answer: Acetylcholine acting on nicotinic receptors
Q3. Which neurotransmitter is predominantly released by sympathetic postganglionic neurons at effector organs?
- Acetylcholine
- Norepinephrine
- Serotonin
- GABA
Correct Answer: Norepinephrine
Q4. The adrenal medulla releases which substances into the circulation when stimulated by sympathetic activity?
- Acetylcholine only
- Only norepinephrine
- Epinephrine and norepinephrine (mainly epinephrine)
- Dopamine only
Correct Answer: Epinephrine and norepinephrine (mainly epinephrine)
Q5. How do sympathetic preganglionic and postganglionic fiber lengths typically compare?
- Long preganglionic, short postganglionic
- Both are long fibers
- Short preganglionic, long postganglionic
- Both are short fibers
Correct Answer: Short preganglionic, long postganglionic
Q6. Which ganglia are paired along the vertebral column forming the sympathetic trunk?
- Prevertebral (collateral) ganglia
- Paravertebral (sympathetic chain) ganglia
- Ciliary ganglia
- Otic ganglia
Correct Answer: Paravertebral (sympathetic chain) ganglia
Q7. How is neurotransmitter release distributed at many sympathetic neuroeffector junctions?
- Single-point synapse like the neuromuscular junction
- Somatic motor endplate release only
- Diffuse release from varicosities along axons
- Gap-junction-mediated release
Correct Answer: Diffuse release from varicosities along axons
Q8. Which mechanism is the major route for terminating synaptic action of norepinephrine in sympathetic nerve terminals?
- Acetylcholinesterase breakdown
- Reuptake via the norepinephrine transporter (NET)
- Diffusion into lymphatics
- Endocytosis by postsynaptic cell
Correct Answer: Reuptake via the norepinephrine transporter (NET)
Q9. What enzymes are mainly responsible for intracellular metabolism of catecholamines?
- Acetylcholinesterase and butyrylcholinesterase
- Monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT)
- Cyclooxygenase and lipoxygenase
- Tyrosine hydroxylase and dopamine β-hydroxylase
Correct Answer: Monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT)
Q10. Activation of α1-adrenergic receptors primarily couples to which G-protein and produces what effect?
- Gs → increased cAMP; bronchodilation
- Gi → decreased cAMP; decreased heart rate
- Gq → increased IP3/DAG; vasoconstriction
- G12/13 → cytoskeletal rearrangement; smooth muscle relaxation
Correct Answer: Gq → increased IP3/DAG; vasoconstriction
Q11. α2-adrenergic receptors commonly mediate which presynaptic effect?
- Facilitation of norepinephrine release
- Increased cAMP to enhance transmitter release
- Inhibition of norepinephrine release via Gi signaling
- Direct stimulation of postsynaptic muscle contraction
Correct Answer: Inhibition of norepinephrine release via Gi signaling
Q12. Which receptor subtype predominates in the heart to increase heart rate and contractility when stimulated?
- α1 adrenergic receptor
- β1 adrenergic receptor
- β2 adrenergic receptor
- Muscarinic M2 receptor
Correct Answer: β1 adrenergic receptor
Q13. Which adrenergic receptor mediates bronchodilation and relaxation of bronchial smooth muscle?
- α2 receptor
- β1 receptor
- β2 receptor
- α1 receptor
Correct Answer: β2 receptor
Q14. Stimulation of which receptor promotes lipolysis in adipose tissue?
- α1 receptor
- α2 receptor
- β3 receptor
- M3 muscarinic receptor
Correct Answer: β3 receptor
Q15. Which drug is a selective α1-adrenergic agonist commonly used as a nasal decongestant and to raise blood pressure?
- Propranolol
- Phenylephrine
- Clonidine
- Metoprolol
Correct Answer: Phenylephrine
Q16. Which drug is a selective β2-adrenergic agonist used as a bronchodilator in asthma?
- Salbutamol (albuterol) – selective β2 agonist
- Prazosin – α1 antagonist
- Propranolol – nonselective β blocker
- Dobutamine – selective α1 agonist
Correct Answer: Salbutamol (albuterol) – selective β2 agonist
Q17. Which centrally acting drug reduces sympathetic outflow by stimulating α2 receptors in the brainstem?
- Phenylephrine
- Clonidine
- Isoproterenol
- Pseudoephedrine
Correct Answer: Clonidine
Q18. A common adverse effect of nonselective β-blockers like propranolol is:
- Bronchodilation due to β2 stimulation
- Bronchoconstriction due to β2 blockade
- Tachycardia due to β1 blockade
- Excessive sweating due to muscarinic activation
Correct Answer: Bronchoconstriction due to β2 blockade
Q19. Mydriasis (pupil dilation) in the sympathetic response is mediated by which receptor on the iris?
- Muscarinic M3 receptor on sphincter pupillae
- Dopaminergic D2 receptor
- α1 receptor on radial muscle
- β1 receptor on ciliary muscle
Correct Answer: α1 receptor on radial muscle
Q20. Which receptor subtype primarily mediates hepatic glycogenolysis in response to sympathetic stimulation?
- α1 receptor
- β1 receptor
- β2 receptor
- α2 receptor
Correct Answer: β2 receptor
Q21. Which class of drugs increases synaptic norepinephrine by inhibiting its enzymatic breakdown?
- Monoamine oxidase (MAO) inhibitors
- Acetylcholinesterase inhibitors
- HMG-CoA reductase inhibitors
- ACE inhibitors
Correct Answer: Monoamine oxidase (MAO) inhibitors
Q22. Amphetamine increases sympathetic neurotransmission primarily by which mechanism?
- Direct α1 receptor agonism only
- Blocking acetylcholine release
- Promoting norepinephrine release and reversing NET
- Inhibiting COMT exclusively
Correct Answer: Promoting norepinephrine release and reversing NET
Q23. An acute rise in arterial blood pressure activates baroreceptors leading to what immediate autonomic response?
- Increased sympathetic outflow and tachycardia
- Reflex inhibition of sympathetic outflow and bradycardia
- No change in autonomic tone
- Increased parasympathetic withdrawal causing hypertension
Correct Answer: Reflex inhibition of sympathetic outflow and bradycardia
Q24. Which drug is a selective α1 antagonist used to treat hypertension and symptoms of pheochromocytoma?
- Prazosin – selective α1 antagonist
- Propranolol – β blocker
- Clonidine – α2 agonist
- Phenylephrine – α1 agonist
Correct Answer: Prazosin – selective α1 antagonist
Q25. Orthostatic hypotension after starting an antihypertensive is most likely due to blockade of which receptor?
- β1 receptors in the heart
- M2 muscarinic receptors
- α1 receptors on vascular smooth muscle
- Dopamine D1 receptors in kidney
Correct Answer: α1 receptors on vascular smooth muscle
Q26. Chronic agonist exposure often produces reduced receptor responsiveness by which cellular mechanism?
- Increased receptor synthesis on membrane
- Receptor phosphorylation by GRKs and β-arrestin-mediated internalization
- Enhanced ligand binding affinity permanently
- Conversion of GPCR to ion channel
Correct Answer: Receptor phosphorylation by GRKs and β-arrestin-mediated internalization
Q27. Sympathetic innervation of eccrine sweat glands uses which neurotransmitter at the effector site?
- Norepinephrine acting on adrenergic receptors
- Acetylcholine acting on muscarinic receptors
- Peptidergic VIP release
- Dopamine acting on D2 receptors
Correct Answer: Acetylcholine acting on muscarinic receptors
Q28. Preganglionic sympathetic fibers synapse on adrenal medulla chromaffin cells using which receptor type?
- Muscarinic receptors
- Nicotinic receptors
- β2 adrenergic receptors
- α1 adrenergic receptors
Correct Answer: Nicotinic receptors
Q29. Sympathetic control of the urinary bladder produces which combination of effects to promote urine retention?
- Contraction of detrusor (α1) and relaxation of internal sphincter (β2)
- Relaxation of detrusor (β3) and contraction of internal sphincter (α1)
- Contraction of detrusor (β3) and relaxation of sphincter (α2)
- No sympathetic influence on bladder function
Correct Answer: Relaxation of detrusor (β3) and contraction of internal sphincter (α1)
Q30. What is meant by ‘sympathetic tone’ in the context of cardiovascular physiology?
- Complete absence of sympathetic activity at rest
- Basal sympathetic activity that maintains vascular resistance and blood pressure
- Sudden maximal sympathetic discharge only during stress
- Exclusive parasympathetic dominance over vessels
Correct Answer: Basal sympathetic activity that maintains vascular resistance and blood pressure
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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