HUMAN ANATOMY & PHYSIOLOGY I & II
Comprehensive Nervous System Examination: 200 Master Questions
with Detailed Rationales
MODULE 1: NEUROHISTOLOGY & MEMBRANE
ELECTROPHYSIOLOGY (QUESTIONS 1–40)
Q1. Which neuroglial cell is responsible for myelin formation in the
Central Nervous System (CNS)? (Variant 1)
A) Schwann cell
B) Astrocyte
C) Oligodendrocyte
D) Microglial cell
Correct Answer: C
Rationale: Oligodendrocytes myelinate axons in the CNS, whereas
Schwann cells perform this function in the PNS. A single
oligodendrocyte can extend processes to myelinate multiple adjacent
axons.
Q2. Which glial cell acts as the primary phagocytic immune cell of
the central nervous system during injury or infection? (Variant 2)
A) Ependymal cell
B) Microglia
C) Satellite cell
D) Astrocyte
Correct Answer: B
Rationale: Microglia are specialized resident macrophages of the
CNS that phagocytize cellular debris, pathogens, and dead neuronal
tissue during inflammation or injury.
,Q3. At resting membrane potential (approx. -70 mV), the neuronal
plasma membrane is most permeable to which of the following ions?
(Variant 3)
A) Sodium (Na+)
B) Calcium (Ca2+)
C) Potassium (K+)
D) Chloride (Cl-)
Correct Answer: C
Rationale: At rest, potassium leak channels are significantly more
numerous and open than sodium leak channels, making the resting
membrane much more permeable to K+ than Na+.
Q4. During an action potential, depolarization is primarily driven
by the rapid influx of which ion through voltage-gated channels?
(Variant 4)
A) Potassium (K+)
B) Sodium (Na+)
C) Calcium (Ca2+)
D) Chloride (Cl-)
Correct Answer: B
Rationale: Depolarization occurs when voltage-gated Na+ channels
open rapidly, allowing Na+ to rush down its electrochemical gradient
into the intracellular fluid, shifting the membrane potential positive.
Q5. Repolarization of the neuronal membrane during an action
potential is caused primarily by: (Variant 5)
A) Influx of Na+
B) Efflux of K+
C) Efflux of Cl-
D) Influx of Ca2+
, Correct Answer: B
Rationale: Repolarization is driven by the opening of voltage-gated
K+ channels and inactivation of Na+ channels, allowing K+ to rush
out of the cell, restoring negative interior potential.
Q6. The absolute refractory period of a neuron is primarily caused
by: (Variant 6)
A) Hyperpolarization due to slow K+ channels
B) Inactivation gates of voltage-gated Na+ channels
C) Depletion of extracellular ATP
D) Closure of voltage-gated Ca2+ channels
Correct Answer: B
Rationale: During the absolute refractory period, voltage-gated Na+
channels are in their inactivated state and cannot be reopened
regardless of stimulus strength, ensuring unidirectional propagation.
Q7. Saltatory conduction occurs along myelinated axons because of
the high concentration of voltage-gated ion channels located at:
(Variant 7)
A) The axon hillock
B) The synaptic knobs
C) The nodes of Ranvier
D) Substantia nigra
Correct Answer: C
Rationale: Nodes of Ranvier contain high concentrations of voltage-
gated Na+ and K+ channels. Myelin insulates the internodes,
allowing the action potential to 'jump' rapidly from node to node.
Q8. Which neurotransmitter is the primary excitatory
neurotransmitter in the mammalian central nervous system?
(Variant 8)
, A) GABA
B) Glycine
C) Glutamate
D) Acetylcholine
Correct Answer: C
Rationale: Glutamate is the principal excitatory amino acid
neurotransmitter in the brain, binding to AMPA, NMDA, and kainate
receptors. GABA and glycine are primary inhibitory
neurotransmitters.
Q9. Botulinum toxin inhibits neuromuscular transmission by
blocking: (Variant 9)
A) Acetylcholine receptor binding
B) SNARE-mediated exocytosis of acetylcholine vesicles
C) Acetylcholinesterase activity
D) Voltage-gated calcium channels in the muscle fiber
Correct Answer: B
Rationale: Botulinum neurotoxin cleaves SNARE proteins required
for the docking and fusion of ACh-containing synaptic vesicles at the
presynaptic terminal, causing flaccid paralysis.
Q10. Myasthenia gravis is an autoimmune disorder characterized by
circulating antibodies directed against: (Variant 10)
A) Presynaptic calcium channels
B) Postsynaptic nicotinic acetylcholine receptors
C) Acetylcholinesterase enzymes
D) Voltage-gated sodium channels
Correct Answer: B
Rationale: Myasthenia gravis involves autoantibodies against
nicotinic ACh receptors at the neuromuscular junction, leading to
Comprehensive Nervous System Examination: 200 Master Questions
with Detailed Rationales
MODULE 1: NEUROHISTOLOGY & MEMBRANE
ELECTROPHYSIOLOGY (QUESTIONS 1–40)
Q1. Which neuroglial cell is responsible for myelin formation in the
Central Nervous System (CNS)? (Variant 1)
A) Schwann cell
B) Astrocyte
C) Oligodendrocyte
D) Microglial cell
Correct Answer: C
Rationale: Oligodendrocytes myelinate axons in the CNS, whereas
Schwann cells perform this function in the PNS. A single
oligodendrocyte can extend processes to myelinate multiple adjacent
axons.
Q2. Which glial cell acts as the primary phagocytic immune cell of
the central nervous system during injury or infection? (Variant 2)
A) Ependymal cell
B) Microglia
C) Satellite cell
D) Astrocyte
Correct Answer: B
Rationale: Microglia are specialized resident macrophages of the
CNS that phagocytize cellular debris, pathogens, and dead neuronal
tissue during inflammation or injury.
,Q3. At resting membrane potential (approx. -70 mV), the neuronal
plasma membrane is most permeable to which of the following ions?
(Variant 3)
A) Sodium (Na+)
B) Calcium (Ca2+)
C) Potassium (K+)
D) Chloride (Cl-)
Correct Answer: C
Rationale: At rest, potassium leak channels are significantly more
numerous and open than sodium leak channels, making the resting
membrane much more permeable to K+ than Na+.
Q4. During an action potential, depolarization is primarily driven
by the rapid influx of which ion through voltage-gated channels?
(Variant 4)
A) Potassium (K+)
B) Sodium (Na+)
C) Calcium (Ca2+)
D) Chloride (Cl-)
Correct Answer: B
Rationale: Depolarization occurs when voltage-gated Na+ channels
open rapidly, allowing Na+ to rush down its electrochemical gradient
into the intracellular fluid, shifting the membrane potential positive.
Q5. Repolarization of the neuronal membrane during an action
potential is caused primarily by: (Variant 5)
A) Influx of Na+
B) Efflux of K+
C) Efflux of Cl-
D) Influx of Ca2+
, Correct Answer: B
Rationale: Repolarization is driven by the opening of voltage-gated
K+ channels and inactivation of Na+ channels, allowing K+ to rush
out of the cell, restoring negative interior potential.
Q6. The absolute refractory period of a neuron is primarily caused
by: (Variant 6)
A) Hyperpolarization due to slow K+ channels
B) Inactivation gates of voltage-gated Na+ channels
C) Depletion of extracellular ATP
D) Closure of voltage-gated Ca2+ channels
Correct Answer: B
Rationale: During the absolute refractory period, voltage-gated Na+
channels are in their inactivated state and cannot be reopened
regardless of stimulus strength, ensuring unidirectional propagation.
Q7. Saltatory conduction occurs along myelinated axons because of
the high concentration of voltage-gated ion channels located at:
(Variant 7)
A) The axon hillock
B) The synaptic knobs
C) The nodes of Ranvier
D) Substantia nigra
Correct Answer: C
Rationale: Nodes of Ranvier contain high concentrations of voltage-
gated Na+ and K+ channels. Myelin insulates the internodes,
allowing the action potential to 'jump' rapidly from node to node.
Q8. Which neurotransmitter is the primary excitatory
neurotransmitter in the mammalian central nervous system?
(Variant 8)
, A) GABA
B) Glycine
C) Glutamate
D) Acetylcholine
Correct Answer: C
Rationale: Glutamate is the principal excitatory amino acid
neurotransmitter in the brain, binding to AMPA, NMDA, and kainate
receptors. GABA and glycine are primary inhibitory
neurotransmitters.
Q9. Botulinum toxin inhibits neuromuscular transmission by
blocking: (Variant 9)
A) Acetylcholine receptor binding
B) SNARE-mediated exocytosis of acetylcholine vesicles
C) Acetylcholinesterase activity
D) Voltage-gated calcium channels in the muscle fiber
Correct Answer: B
Rationale: Botulinum neurotoxin cleaves SNARE proteins required
for the docking and fusion of ACh-containing synaptic vesicles at the
presynaptic terminal, causing flaccid paralysis.
Q10. Myasthenia gravis is an autoimmune disorder characterized by
circulating antibodies directed against: (Variant 10)
A) Presynaptic calcium channels
B) Postsynaptic nicotinic acetylcholine receptors
C) Acetylcholinesterase enzymes
D) Voltage-gated sodium channels
Correct Answer: B
Rationale: Myasthenia gravis involves autoantibodies against
nicotinic ACh receptors at the neuromuscular junction, leading to
