APMLE Part 1 Neurophysiology Questions With Complete
Solutions
1. Which autonomic receptor is blocked by hexamethonium at
the ganglia, but not at the neuromuscular junction?
(A) Adrenergic αreceptors (B) Adrenergic β1 receptors
(C) Adrenergic β2 receptors
(D) Cholinergic muscarinic receptors
(E) Cholinergic nicotinic receptors Correct Answers E
Hexamethonium is a nicotinic blocker, but it acts only at
ganglionic (not neuromuscular junction) nicotinic receptors.
This pharmacologic distinction emphasizes that nicotinic
receptors at these two locations, although similar, are not
identical.
10. Which reflex is responsible for monosynaptic excitation of
ipsilateral homonymous muscle?
(A) Stretch reflex (myotatic)
(B) Golgi tendon reflex (inverse myotatic)
(C) Flexor withdrawal reflex
(D) Subliminal occlusion reflex Correct Answers A The stretch
reflex is the monosynaptic response to stretching of a muscle.
The reflex produces contraction and then shortening of the
muscle that was originally stretched (homonymous muscle).
11. Which type of cell in the visual cortex responds best to a
moving bar of light?
(A) Simple
,(B) Complex
(C) Hypercomplex
(D) Bipolar
(E) Ganglion Correct Answers B Complex cells respond to
moving bars or edges with the correct orientation. Simple cells
respond to stationary bars, and hypercomplex cells respond to
lines, curves, and angles. Bipolar and ganglion cells are found in
the retina, not in the visual cortex.
12. Administration of which of the following drugs is
contraindicated in a 10-year-old child with a history of asthma?
(A) Albuterol
(B) Epinephrine
(C) Isoproterenol (D) Norepinephrine (E) Propranolol Correct
Answers E Asthma, a disease involving increased resistance of
the upper airways, is treated by administering drugs that produce
bronchiolar dilation (i.e., β2 agonists). β2 Agonists include
isoproterenol, albuterol, epinephrine, and, to a lesser extent,
norepinephrine. β2 Antagonists, such as propranolol, are strictly
contraindicated because they cause constriction of the
bronchiole
13. Which adrenergic receptor produces its stimulatory effects
by the formation of inositol 1,4,5-triphosphate (IP3) and an
increase in intracellular [Ca2+]?
(A) α1 Receptors
(B) α2 Receptors
(C) β1 Receptors
(D) β2 Receptors (E) Muscarinic receptors
,(F) Nicotinic receptor Correct Answers A Adrenergic α1
receptors produce physiologic actions by stimulating the
formation of inositol 1,4,5-triphosphate (IP3) and causing a
subsequent increase in intracellular [Ca2+]. Both β1 and β2
receptors act by stimulating adenylate cyclase and increasing the
production of cyclic adenosine monophosphate (cAMP). α2
Receptors inhibit adenylate cyclase and decrease cAMP levels.
Muscarinic and nicotinic receptors are cholinergic.
14. The excessive muscle tone produced in decerebrate rigidity
can be reversed by
(A) stimulation of group Ia afferents
(B) cutting the dorsal roots
(C) transection of cerebellar connections to the lateral vestibular
nucleus
(D) stimulation of α-motoneurons
(E) stimulation of γ-motoneurons Correct Answers B
Decerebrate rigidity is caused by increased reflex muscle spindle
activity. Stimulation of group Ia afferents would enhance, not
diminish, this reflex activity. Cutting the dorsal roots would
block the reflexes. Stimulation of α- and γ-motoneurons would
stimulate muscles directly.
15. Which of the following parts of the body has cortical
motoneurons with the largest representation on the primary
motor cortex (area 4)?
(A) Shoulder
(B) Ankle
(C) Fingers
, (D) Elbow
(E) Knee Correct Answers C
16. Which autonomic receptor mediates secretion of epinephrine
by the adrenal medulla?
(A) Adrenergic αreceptors
(B) Adrenergic β1 receptors
(C) Adrenergic β2 receptors
(D) Cholinergic muscarinic receptors
(E) Cholinergic nicotinic receptors Correct Answers E
Preganglionic sympathetic fibers synapse on the chromaffin
cells of the adrenal medulla at a nicotinic receptor. Epinephrine
and, to a lesser extent, norepinephrine are released into the
circulation.
17. Cutting which structure on the right side causes blindness in
the temporal field of the left eye and the nasal field of the right
eye?
(A) Optic nerve
(B) Optic chiasm
(C) Optic tract
(D)Geniculocalcarine tract Correct Answers C Fibers from the
left temporal field and the right nasal field ascend together in the
right optic tract
18. A ballet dancer spins to the left. During the spin, her eyes
snap quickly to the left. This fast eye movement is
(A) nystagmus
Solutions
1. Which autonomic receptor is blocked by hexamethonium at
the ganglia, but not at the neuromuscular junction?
(A) Adrenergic αreceptors (B) Adrenergic β1 receptors
(C) Adrenergic β2 receptors
(D) Cholinergic muscarinic receptors
(E) Cholinergic nicotinic receptors Correct Answers E
Hexamethonium is a nicotinic blocker, but it acts only at
ganglionic (not neuromuscular junction) nicotinic receptors.
This pharmacologic distinction emphasizes that nicotinic
receptors at these two locations, although similar, are not
identical.
10. Which reflex is responsible for monosynaptic excitation of
ipsilateral homonymous muscle?
(A) Stretch reflex (myotatic)
(B) Golgi tendon reflex (inverse myotatic)
(C) Flexor withdrawal reflex
(D) Subliminal occlusion reflex Correct Answers A The stretch
reflex is the monosynaptic response to stretching of a muscle.
The reflex produces contraction and then shortening of the
muscle that was originally stretched (homonymous muscle).
11. Which type of cell in the visual cortex responds best to a
moving bar of light?
(A) Simple
,(B) Complex
(C) Hypercomplex
(D) Bipolar
(E) Ganglion Correct Answers B Complex cells respond to
moving bars or edges with the correct orientation. Simple cells
respond to stationary bars, and hypercomplex cells respond to
lines, curves, and angles. Bipolar and ganglion cells are found in
the retina, not in the visual cortex.
12. Administration of which of the following drugs is
contraindicated in a 10-year-old child with a history of asthma?
(A) Albuterol
(B) Epinephrine
(C) Isoproterenol (D) Norepinephrine (E) Propranolol Correct
Answers E Asthma, a disease involving increased resistance of
the upper airways, is treated by administering drugs that produce
bronchiolar dilation (i.e., β2 agonists). β2 Agonists include
isoproterenol, albuterol, epinephrine, and, to a lesser extent,
norepinephrine. β2 Antagonists, such as propranolol, are strictly
contraindicated because they cause constriction of the
bronchiole
13. Which adrenergic receptor produces its stimulatory effects
by the formation of inositol 1,4,5-triphosphate (IP3) and an
increase in intracellular [Ca2+]?
(A) α1 Receptors
(B) α2 Receptors
(C) β1 Receptors
(D) β2 Receptors (E) Muscarinic receptors
,(F) Nicotinic receptor Correct Answers A Adrenergic α1
receptors produce physiologic actions by stimulating the
formation of inositol 1,4,5-triphosphate (IP3) and causing a
subsequent increase in intracellular [Ca2+]. Both β1 and β2
receptors act by stimulating adenylate cyclase and increasing the
production of cyclic adenosine monophosphate (cAMP). α2
Receptors inhibit adenylate cyclase and decrease cAMP levels.
Muscarinic and nicotinic receptors are cholinergic.
14. The excessive muscle tone produced in decerebrate rigidity
can be reversed by
(A) stimulation of group Ia afferents
(B) cutting the dorsal roots
(C) transection of cerebellar connections to the lateral vestibular
nucleus
(D) stimulation of α-motoneurons
(E) stimulation of γ-motoneurons Correct Answers B
Decerebrate rigidity is caused by increased reflex muscle spindle
activity. Stimulation of group Ia afferents would enhance, not
diminish, this reflex activity. Cutting the dorsal roots would
block the reflexes. Stimulation of α- and γ-motoneurons would
stimulate muscles directly.
15. Which of the following parts of the body has cortical
motoneurons with the largest representation on the primary
motor cortex (area 4)?
(A) Shoulder
(B) Ankle
(C) Fingers
, (D) Elbow
(E) Knee Correct Answers C
16. Which autonomic receptor mediates secretion of epinephrine
by the adrenal medulla?
(A) Adrenergic αreceptors
(B) Adrenergic β1 receptors
(C) Adrenergic β2 receptors
(D) Cholinergic muscarinic receptors
(E) Cholinergic nicotinic receptors Correct Answers E
Preganglionic sympathetic fibers synapse on the chromaffin
cells of the adrenal medulla at a nicotinic receptor. Epinephrine
and, to a lesser extent, norepinephrine are released into the
circulation.
17. Cutting which structure on the right side causes blindness in
the temporal field of the left eye and the nasal field of the right
eye?
(A) Optic nerve
(B) Optic chiasm
(C) Optic tract
(D)Geniculocalcarine tract Correct Answers C Fibers from the
left temporal field and the right nasal field ascend together in the
right optic tract
18. A ballet dancer spins to the left. During the spin, her eyes
snap quickly to the left. This fast eye movement is
(A) nystagmus
