MCQ Quiz

Q1. Which feature correctly distinguishes sympathetic from parasympathetic outflow?

Long preganglionic and long postganglionic fibers

Short preganglionic and long postganglionic fibers

Origin from cranial nerves only

All postganglionic fibers are cholinergic

Explanation:
Sympathetic nerves arise from T1–L3 with short preganglionic and long postganglionic fibers.

Q2. All preganglionic autonomic fibers release acetylcholine acting on:

Nicotinic receptors

Muscarinic receptors

α-adrenergic receptors

β-adrenergic receptors

Explanation:
Preganglionic fibers of both SNS and PSNS are cholinergic acting on nicotinic receptors in ganglia.

Q3. Which sympathetic postganglionic fibers are cholinergic?

Cardiac muscle

Most blood vessels

Sweat glands

Adrenal medulla

Explanation:
Sweat glands are supplied by sympathetic cholinergic fibers acting on muscarinic receptors.

Q4. Muscarinic receptors in the heart are predominantly of which subtype?

M1

M2

M3

M5

Explanation:
M2 receptors predominate in the heart, reducing heart rate and contractility.

Q5. Parasympathetic stimulation of the gastrointestinal tract causes:

Relaxation of intestinal wall

Contraction of sphincters

Decreased motility

Contraction of wall muscles with sphincter relaxation

Explanation:
Muscarinic activation increases gut motility and relaxes sphincters.

Q6. Norepinephrine acts mainly on which adrenergic receptor type?

α receptors

β receptors

β2 receptors only

β3 receptors

Explanation:
Norepinephrine primarily stimulates α receptors and only weakly β receptors.

Q7. Which effect is mediated by α1-adrenergic receptor stimulation?

Bronchodilation

Glycogenolysis

Vasoconstriction

Increased insulin secretion

Explanation:
α1 receptor activation causes vasoconstriction and pupillary dilation.

Q8. Which adrenergic receptor mediates bronchodilation?

α2

β2

β1

α1

Explanation:
β2 receptor stimulation causes bronchodilation and smooth muscle relaxation.

Q9. Denervation hypersensitivity occurs mainly due to:

Decreased neurotransmitter release

Increased acetylcholinesterase activity

Loss of action potentials

Up-regulation of receptors

Explanation:
Loss of nerve supply leads to increased receptor number and sensitivity.

Q10. Penile erection is mediated predominantly by:

Parasympathetic vasodilation

Sympathetic vasoconstriction

Somatic motor neurons

Adrenal medullary hormones

Explanation:
Parasympathetic activity causes vasodilation leading to erection.

Q11. The adrenal medulla is functionally equivalent to:

A sympathetic ganglion with postganglionic fibers

A parasympathetic ganglion

Postganglionic sympathetic neurons without axons

Somatic motor neurons

Explanation:
Adrenal medulla cells act like postganglionic sympathetic neurons that secrete catecholamines.

Q12. The prolonged action of adrenal catecholamines is mainly due to:

Faster degradation

Hormonal release into bloodstream

Local synaptic action

Reduced receptor affinity

Explanation:
Hormonal secretion allows widespread and prolonged effects.

Q13. Visceral pain is typically:

Sharp and well localized

Carried by parasympathetic fibers

Transmitted by Aα fibers

Diffuse and often referred

Explanation:
Visceral pain is diffuse, poorly localized, and often referred to somatic areas.

Q14. Visceral nociceptive pain fibers travel mainly with:

Sympathetic nerves

Parasympathetic nerves

Somatic motor nerves

Cranial motor nerves

Explanation:
Visceral nociceptors are carried exclusively by sympathetic fibers.

Q15. Which center directly controls body temperature regulation?

Posterior pituitary

Medulla oblongata

Preoptic area of hypothalamus

Cerebellum

Explanation:
The anterior hypothalamus (preoptic area) contains temperature-sensitive neurons.

Q16. Exposure to cold activates which hypothalamic region?

Anterior hypothalamus

Posterior hypothalamus

Ventromedial nucleus

Supraoptic nucleus

Explanation:
Posterior hypothalamus increases heat production and reduces heat loss.

Q17. Fever differs from hyperthermia because in fever:

Heat loss mechanisms fail

Sweating is absent

Hypothalamus is damaged

Thermostatic set point is raised

Explanation:
Fever involves resetting the hypothalamic set point to a higher level.

Q18. Aspirin reduces fever mainly by inhibiting:

Prostaglandin synthesis

Catecholamine release

Cytokine production

Heat production in muscle

Explanation:
Aspirin blocks prostaglandin formation in the hypothalamus.

Q19. Destruction of the ventromedial hypothalamic nucleus causes:

Aphagia

Obesity

Anorexia

Hyperthermia

Explanation:
The ventromedial nucleus is the satiety center; its destruction causes hyperphagia and obesity.

Q20. Which hormone increases food intake by acting on the hypothalamus?

Leptin

Peptide YY

Ghrelin

Insulin

Explanation:
Ghrelin is a hunger hormone that stimulates feeding behavior.

Q21. Thirst sensation due to increased plasma osmolarity is mediated by:

Osmoreceptors in anterior hypothalamus

Baroreceptors in carotid sinus