Autonomic Nervous System Pre Quiz

Which neurotransmitter is the primary mediator at all preganglionic autonomic synapses?

• Norepinephrine

• Dopamine

• Acetylcholine

• Epinephrine

Muscarinic receptor stimulation at the heart typically produces which effect?

• Tachycardia

• Bradycardia

• Increased contractility

• Coronary vasoconstriction

A patient receives atropine before anesthesia. Which physiologic effect MOST likely results?

• Reduced sympathetic tone

• Inhibition of nicotinic receptors at neuromuscular junctions

• Blockade of muscarinic receptors → tachycardia

• Enhanced release of norepinephrine from presynaptic terminals

Which receptor subtype mediates vasoconstriction in most vascular smooth muscle?

• β1

• β2

• α1

• α2

During a ganglionic nicotine challenge, a patient first experiences hypertension and tachycardia, followed by hypotension and weakness. This represents:

• Muscarinic blockade

• Nicotinic receptor stimulation then blockade

• α1 receptor antagonism

• β2 receptor stimulation

Which second messenger system is activated by β-adrenergic receptors?

• Phospholipase C → IP3/DAG

• Adenylyl cyclase → cAMP

• Tyrosine kinase → MAPK

• Guanylyl cyclase → cGMP

A patient on chronic β-blocker therapy undergoes anesthesia. Which autonomic change is MOST expected?

• Enhanced baroreceptor sensitivity

• Blunted heart rate response to hypotension

• Exaggerated bronchodilation response

• Increased renin release

Which statement is TRUE regarding adrenal medulla innervation?

• It is controlled by postganglionic sympathetic fibers.

• Preganglionic sympathetic fibers release norepinephrine.

• Preganglionic sympathetic fibers release acetylcholine onto chromaffin cells.

• Adrenal medulla primarily releases acetylcholine into the blood.

An anesthetized patient develops severe bradycardia after opioid administration. Which autonomic mechanism explains this?

• Enhanced sympathetic output

• Increased vagal (parasympathetic) tone at muscarinic receptors

• Blockade of α2 adrenergic receptors

• Inhibition of nicotinic ganglionic transmission

A patient with Horner's syndrome (miosis, ptosis, anhidrosis) most likely has damage to which autonomic pathway?

• Parasympathetic cranial nerve III fibers

• Sympathetic pathway from hypothalamus to superior cervical ganglion

• Somatic motor pathway to eyelid muscles

• Presynaptic muscarinic receptor in the myocardium