Neurophysiology

Question 1

Which one of the following is NOT a component of the blood-brain barrier?
a. Capillary endothelial cells
b. Astrocytic foot processes
c. Basement membrane
d. Tight junctions
e. Microglia

Answer 1

e. Microglia

Question 2

Which one of the following regions has an
intact blood-brain barrier?
a. Subforniceal organ
b. Area postrema
c. Median eminence
d. Posterior pituitary
e. Pineal gland
f. Subcommissural organ
g. Organum vasculosum of lamina
terminalis

Answer 2

f. Subcommissural organ

Question 3

Which one of the following statements regarding the area postrema is LEAST accurate?
a. It is located in the dorsomedial medulla in
the caudal part of the fourth ventricle
b. Its blood supply is mostly from the anterior inferior cerebellar artery
c. It is a circumventricular organ
d. It plays a role as a chemoreceptor
trigger zone
e. It expresses 5-HT3 receptors

Answer 3

a. It is located in the dorsomedial medulla in
the caudal part of the fourth ventricle

Question 4

Which one of the following statements
regarding the production of CSF by choroid
plexus cells is LEAST accurate?
a. Requires ultrafiltration of plasma to form
extracellular fluid at basolateral membrane
b. Formation is primarily generated by net
secretion of Na+, Cl-, and HCO3- into ventricles
c. Water is actively pumped into the ventricles via Aquaporin 1 channels in the apical membrane
d. Active transport of Na+ into the ventricles
via Na+ /K+ ATPase occurs at the basolateral membrane
e. Basolateral membrane Na influx via Na+/H+ exchange and Na+/HCO3- cotransport channels.

Answer 4

c. Water is actively pumped into the ventricles via Aquaporin 1 channels in the apical membrane

Question 5

Which one of the following statements regarding axonal transport is LEAST accurate?
a. Large membranous organelles are transported by fast kinesin dependent anterograde transport and dynein dependent
retrograde transport
b. Cytosolic proteins are transported by fast transport
c. Occurs by retrograde transport
d. Anterograde transport is dependent upon
microtubules and the ATPase kinesin
e. Rabies virus spreads by retrograde axonal
transport

Answer 5

b. Cytosolic proteins are transported by fast transport

Question 6

Which one of the following statements
regarding ion channels is LEAST accurate?
a. Nicotinic AChR is a ligand-gated ion
channel
b. NMDA receptor is a ligand-gated cation
channel
c. Voltage-gated sodium channels open in
response to hyperpolarization of the cell
membrane
d. Cyclic AMP is generated by activation of
beta-adrenoceptors
e. GABA-B receptor is a ligand-gated ion channel

Answer 6

e. GABA-B receptor is a ligand-gated ion channel

Question 7

Which one of the following statements
regarding the membrane potentials is most
accurate?
a. The Nernst equation can be used to calculate the resting membrane potential of
a cell
b. The Goldman equation can be used to
calculate the intracellular concentration
of sodium
c. The equilibrium potential for potassium
is approximately +70 mV
d. Equilibrium potential of an ion maintains
a unique ion gradient for it exists across a
cell membrane
e. At electrochemical equilibrium, the
chemical and electrical driving forces acting on an ion are equal and opposite, and
no further net diffusion occurs

Answer 7

e. At electrochemical equilibrium, the
chemical and electrical driving forces acting on an ion are equal and opposite, and
no further net diffusion occurs

Question 8

Which one of the following best describes ions
responsible for membrane hyperpolarization?
a. Chloride and sodium
b. Chloride and potassium
c. Potassium and sodium
d. Sodium and calcium
e. Sodium only

Answer 8

b. Chloride and potassium

Question 9

Which one of the following statements
regarding the passive membrane properties
of neurons is LEAST accurate?
a. The length constant is the distance where
the initial voltage response to current flow
decays to 1/e (or 37%) of its value
b. Smaller length constant means passive
flow of an action potential will stop at a
shorter distance along an axon
c. Length constant is greater in unmyelinated and large diameter axons
d. The time constant is a function of the
membrane’s resistance and capacitance
e. The time constant characterizes how rap-
idly current flow changes the membrane
potential

Answer 9

c. Length constant is greater in unmyelinated and large diameter axons

Question 10

Which one of the following statements
regarding the generation of the action potential is LEAST accurate?
a. It is an all-or-nothing, regenerative wave
of depolarization
b. It can propagate bidirectionally
c. Repolarization is due to inactivation of
sodium channels combined with increased
conductance in potassium channels
d. Hyperpolarization occurs due to increases
in potassium conductance lasting beyond
the point of return to resting membrane
potential
e. Repolarization is required for inactivated
sodium channels to return to the closed state

Answer 10

b. It can propagate bidirectionally

Question 11

Which one of the following sites acts as the
trigger zone that integrates incoming signals
from other cells and initiates the action
potential?
a. Soma
b. Dendritic shaft
c. Dendritic spines
d. Axon hillock and initial segment
e. Axon trunk

Answer 11

d. Axon hillock and initial segment

Question 12

Which one of the following statements
regarding phenomena relevant to action
potential conduction is LEAST accurate?
a. Accommodation is dependent on postsyn-
aptic receptor phagocytosis
b. Saltatory conduction occurs to high resis-
tance to transmembrane current leak in
myelinated segments of nerve
c. Absolute refractory period is due to inac-
tivation of voltage-gated sodium channels
d. Relative refractory period occurs when
populations of inactivated voltage-gated
sodium channels return to the closed state
e. Unidirectional propagation is function of
the refractory periods associated with
action potentials

Answer 12

a. Accommodation is dependent on postsyn-
aptic receptor phagocytosis

Question 13

Which one of the following synapse types is
characterized by gap junctions?
a. Axodendritic synapses
b. Axoaxonic synapses
c. Axosomatic synapses
d. Dendrodendritic synapses
e. Electrical synapses

Answer 13

e. Electrical synapses

Question 14

Which one of the following statements
regarding neurotransmission at chemical
synapses is LEAST accurate?
a. The action potential stimulates the
postsynaptic terminal to release
neurotransmitter
b. Release of the transmitter into the synaptic
cleft by exocytosis is triggered by an influx
of Ca2+ through voltage-gated channels
c. Postsynaptic current produces an excit-
atory or inhibitory postsynaptic potential
d. Neurotransmitters may undergo degrada-
tion in the synaptic cleft or be transported
back into the presynaptic terminal
e. Vesicular membrane is retrieved from the
plasma membrane after exocytosis

Answer 14

a. The action potential stimulates the
postsynaptic terminal to release
neurotransmitter

Question 15

Which one of the following statements
regarding cholinergic neurotransmission is
LEAST likely?
a. synthesized in nerve terminals from the
precursors acetyl coenzyme A
b. acetylcholinesterase (AChE) hydrolysis
Ach into acetate and choline
c. Nicotinic AChR are a nonselective cation
channel complex consisting of five subunits
arranged around a central membrane-
spanning pore
d. α-bungarotoxin binds to muscarinic AChRs
e. mAChRs are metabotropic G-protein
coupled receptors

Answer 15

d. α-bungarotoxin binds to muscarinic AChRs

Question 16

Which one of the following statements
regarding glutamatergic neurotransmission
is LEAST accurate?
a. At depolarized membrane potentials, an
Mg2+ blocks the pore of the NMDA
receptor
b. most prevalent precursor for glutamate
synthesis is glutamine
c. glutamine is taken up into presynaptic ter-
minals and metabolized to glutamate by
the mitochondrial enzyme glutaminase
d. Activation of metabotropic GluRs leads to
inhibition of postsynaptic Ca2+ and Na+
channels
e. AMPA receptors are a type of metabotropic GluR

Answer 16

e. AMPA receptors are a type of metabotropic GluR

Question 17

Which one of the following enzymatic con-
version pathways is LEAST accurate?
a. Tyrosine-tyrosine hydroxylase-DOPA
(dihydroxyphenylalanine)
b. DOPA-catechol O-methyltransferase-
dopamine
c. Histidine-histidine decarboxylase-
Histamine
d. Dopamine-Dopamine beta-hydroxylase-
Norepinephrine
e. Tryptophan is converted to serotonin
by tryptophan 5-hydroxylase and a
decarboxylase

Answer 17

b. DOPA-catechol O-methyltransferase-
dopamine

Question 18

Which one of the following statements
regarding dopaminergic neurotransmission
is LEAST accurate?
a. Dopamine is loaded into synaptic vesicles
via a vesicular monoamine transporter
(VMAT)
b. The neostriatum is the major site of dopa-minergic transmission in the brain
c. Dopamine is derived from norepinephrine
d. Cocaine inhibits the Na-dependent dopamine transporter
e. monoamine oxidase (MAO) and catechol
O-methyltransferase (COMT)

Answer 18

c. Dopamine is derived from norepinephrine

Question 19

Which one of the following statements
regarding GABAergic neurotransmission is
LEAST accurate?
a. Glutamic acid decarboxylase (GAD) conversion of glutamate to GABA
b. Vitamin B6 is important in the function of glutamic acid decarboxylase
c. The mechanism of GABA removal from the synaptic cleft is similar to that for glutamate
d. GABAA and GABAC receptors are iono tropic receptors and are Ca2+ conductors
e. GABAB receptors are metabotropic and
increase K conductance

Answer 19

d. GABAA and GABAC receptors are iono tropic receptors and are Ca2+ conductors

Question 20

Which one of the following areas does the superior temporal gyrus (Heschl’s gyrus)
primarily receive inputs from?
a. Centromedian thalamic nucleus
b. Medial geniculate thalamic nucleus
c. Dorsomedial thalamic nucleus
d. Anterior thalamic nucleus
e. Centromedian-parafascicular nucleus

Answer 20

b. Medial geniculate thalamic nucleus

Question 21

Which one of the following cell types
involved in vision is able to generate an action
potential?
a. Ganglion cells
b. Bipolar cells
c. Horizontal cells
d. Rods and cones
e. Amacrine cells

Answer 21

a. Ganglion cells

Question 22

Which one of the following statements
regarding cones and rods is LEAST accurate?
a. In the dark, rods have a high resting membrane potential of about -70 mV
b. In the dark, both rods and cones tonically release glutamate onto synapsing
bipolar cells
c. Photon absorption by rhodopsin results in
reduced cyclic GMP and hyperpolarization of the rod cell
d. Photon absorption by cone opsin results
in reduced cyclic GMP and hyperpolarization of the rod cell
e. Reduced glutamate secretion can cause
both hyperpolarization or depolarization
in bipolar cells

Answer 22

a. In the dark, rods have a high resting membrane potential of about -70 mV

Question 23

Which one of the following events during
visual processing is LEAST accurate?
a. The on-center bipolar depolarizes in response to reduced tonic glutamate release
b. The on-center ganglion cell will produce a burst of action potentials if a spot of light is shone on the receptive field center
c. The ganglion cell that receives its input from an off-center bipolar cell will reduce
its firing rate in response a spot of light is shone on the receptive field center
d. The receptive fields of on-center and off-center ganglion cells do not overlap
e. Glutamate released from a cone cell has differential effect in different cells with
which it synapses

Answer 23

d. The receptive fields of on-center and off-center ganglion cells do not overlap

Question 24

Which one of the following statements about
olfaction is LEAST accurate?
a. Bowman glands secrete a fluid that bathes the cilia of the receptors and acts as a solvent for odorant molecules
b. Mucus-coated olfactory epithelium lines the anterodorsal parts of the nasal cavities
c. Binding of odor molecules generates action potentials in a G-protein coupled mechanism
d. Fibers of CN I synapse with the mitral cells of the olfactory bulb
e. Olfactory tract and lateral olfactory stria project to the primary olfactory cortex and amygdala

Answer 24

b. Mucus-coated olfactory epithelium lines the anterodorsal parts of the nasal cavities

Question 25

Which one of the following statements regarding taste sensation is LEAST accurate?
a. Receptors for molecules associated with sweet and bitter tastes utilize second messengers
b. Sour and salty-tasting molecules act directly upon the ion channels
c. Taste buds on the anterior two thirds of the tongue sendsignals through the lingual nerve to the chorda tympani and finally into CN VII (facial)
d. Posterior one-third of the tongue detects bitter and sour tastes and signal through glossopharyngeal and vagus nerves
e. All taste fibers synapse in the nucleus ambiguus

Answer 25

e. All taste fibers synapse in the nucleus ambiguus

Question 26

Which one of the following statements concerning neurotransmission at the neuromuscular junction is most accurate?
a. It is dependent upon the release of norepinephrine from the nerve ending
b. End plate potential amplitude can be much larger than that of excitatory or inhibitory postsynaptic potentials
c. It is an all-or-none response
d. It is not directly related to the concentration of transmitter released from the pre-
synaptic terminals
e. It is dependent on the opening of ligandgated calcium channels

Answer 26

b. End plate potential amplitude can be much larger than that of excitatory or inhibitory postsynaptic potentials

Question 27

Which one of the following statements regarding peripheral nerve injury is most accurate?
a. Neuropraxia involves disruption of the
myelin sheath only with some evidence
of Wallerian degeneration
b. Recovery after neuropraxia is likely to be
incomplete
c. Neurotmesis is ideally managed with
expectant management
d. Axonotmesis shows Wallerian degeneration distal to injury
e. A dense motor and sensory deficit following a penetrating injury is due to
neuropraxia

Answer 27

d. Axonotmesis shows Wallerian degeneration distal to injury

Question 28

Which one of the following ensures sufficient
contraction of the striated portion of intrafusal fibers to enable monitor changes in muscle length?
a. Unmyelinated C fibers
b. 1A fibers
c. Gamma motor neurons
d. Alpha motor neurons
e. General visceral efferent fibers

Answer 28

c. Gamma motor neurons

Question 29

Neurotoxins and other agents:
a. 3,4-Methylenedioxy-methamphetamine
b. Botulinum toxin
c. Bungarotoxin
d. Curare
e. Chlorotoxin
f. Conotoxin
g. Ethanol
h. Phencyclidine (PCP)
i. Tetraethylammonium (TEA)
j. Tetrodotoxin (TTX)

For each of the following descriptions, select the
most appropriate answers from the list above.
Each answer may be used once, more than once
or not at all.
1. Uncompetitive NMDA receptor antagonist
producing dissociative state
2. Works by presynaptic competitive reuptake
inhibition followed by inhibition of VMAT
and TAAR1 receptor resulting in synaptic
accumulation of monoamines.
3. Neurotoxic peptides isolated from venom
of marin cone snail.
4. Blocker of voltage-gated K+ channels and competitive inhibitor of nicotinic AChRs
5. Blocker of voltage-gated Na+ channels found in Pufferfish

Answer 29

1—h, PCP; 2—a, 3,4-methylenedioxy-methamphetamine; 3—f, Conotoxin; 4—i, Tetraethylammonium (TEA); 5—j, Tetrodotoxin (TTX)

Question 30

Neurotransmitters:
a. Acetylcholine
b. Dopamine
c. Epinephrine
d. GABA
e. Glutamate
f. Glycine
g. Histamine
h. L-DOPA
i. Met-enkephalin
j. Serotonin
k. Substance P
l. Taurine
m. Tyramine
n. VIP

For each of the following descriptions, select the
most appropriate answers from the list above.
Each answer may be used once, more than once
or not at all.
1. The immediate precursor of norepinephrine
2. The immediate precursor of dopamine
3. Rate limiting step in the production of this
neurotransmitter is tryptophan hydroxylase
activity
4. Phenylethanolamine-N-methyl transferase
is required for production of this
transmitter
5. Required in addition to glutamate for
co-activation of NMDA receptor, but acts
as an inhibitory neurotransmitter via Cl
channels

Answer 30

1—b,Dopamine.The conversion of dopamine
to norepinephrine comes about by the action of
the enzyme dopamine #-hydroxylase
2—h, L-DOPA. The biosynthesis of catecholamines includes the following steps: tyrosine
is converted into L-dihydroxyphenylalanine
(L-DOPA) by tyrosine hydroxylase.
L-DOPA is then decarboxylated by a decarboxylase to form dopamine (and CO2)
3—j, Serotonin. Tryptophan is converted to
5-hydroxytryptophan by tryptophan
hydroxylase and by 5-hydroxytryptophan
decarboxylase into serotonin
4—c, Epinephrine. Norepinephrine is
converted into epinephrine by
phenylethanolamine-N-methyl transferase
5—f, Glycine

Question 31

Sensory receptors:
a. Free nerve endings
b. Golgi tendon organs
c. Meissner’s corpuscles
d. Merkel’s tactile discs
e. Nuclear bag fibers
f. Nuclear chain fibers
g. Pacinian corpuscles
h. Pain nociceptors
i. Peritrichial nerve endings
j. Ruffini’s organs

For each of the following descriptions, select the
most appropriate answers from the list above.
Each answer may be used once, more than once
or not at all.
1. Signal the onset of muscle stretch via A-alpha myelinated fibers
2. Two-point discriminative fine touch
3. Deep pressure and vibration sense

Answer 31

1—e, Nuclear bag fibers; 2—c, Meissner’s corpuscles; 3—g, Pacinian corpuscles

Question 32

CNS cells:
a. Astrocytes
b. Basket cells
c. Betz cells
d. Ependymal cells
e. Golgi type 2 cells
f. Granule cells
g. Martinotti cells
h. Microglia
i. Oligodendroglia
j. Purkinje cells
k. Schwann cells
l. Stellate cells

For each of the following descriptions, select the
most appropriate answers from the list above.
Each answer may be used once, more than once
or not at all.
1. These cells are derived from neural crest
origin and myelinate neurons of the PNS
2. These cells arise from monocytes (hemato-
poietic precursor) and thus are the resident
macrophages of the CNS. Their function is
to protect the CNS. When the brain is
damaged or infected, they become activated and multiply quickly to perform functions such as phagocytosis and presenting antigen
3. These cells myelinate neurons within the
CNS (one cell myelinates multiple neurons).
4. These are the most abundant and largest of
the glial subtypes. Their most notable role
is the metabolism and recycling of certain
neurotransmitters (glutamate, serotonin,
and gamma-aminobutyric acid [GABA]).
They also buffer the extracellular potassium
concentration, respond to injury (gliosis),
and make up the blood-brain barrier
5. These ciliated cells line the cavities of the CNS (ventricular system) in the choroid plexus, where they are involved in the production of cerebrospinal fluid (CSF) and are part of the blood-CSF barrier

Answer 32

1—k, Schwann cells; 2—h, Microglia; 3—i,
Oligodendrocytes; 4—a, Astrocytes; 5—d,
Ependymal cells

Question 33

Cerebellum:
For each of the following descriptions, select the
most appropriate answers from the image above.
Each answer may be used once, more than once
or not at all.
1. Posterior lobe
2. Flocculus
3. Primary fissure
4. Dentate nucleus
5. Anterior inferior cerebellar artery

Answer 33

1—l, 2—o, 3—k, 4—d, 5—h

Question 34

Cerebellar cortex:
For each of the following descriptions, select the
most appropriate answers from the image above.
Each answer may be used once, more than once
or not at all.
1. Purkinje cell axon
2. Basket cell
3. Climbing fiber
4. Golgi cell
5. Parallel fiber

Answer 34

1—m, 2—d, 3—k, 4—a, 5—g

Question 35

Hypothalamic-pituitary axis:
a. ACTH
b. ADH (vasopressin)
c. Cortisol
d. Epinephrine
e. FSH/LH
f. GH
g. TSH
h. Oestradiol
i. Oxytocin
j. Prolactin
k. Testosterone
For each of the following descriptions, select the
most appropriate answers from the list above.
Each answer may be used once, more than once
or not at all.
1. Uterine contractions in labor and milk ejec-
tion reflex
2. Renal water conservation
3. Excess may cause galactorrhea

Answer 35

1—i, Oxytocin; 2—b, ADH (Vasopressin); 3—j, Prolactin

Question 36

Peripheral nerve:
For each of the following descriptions, select the
most appropriate answers from the image above.
Each answer may be used once, more than once
or not at all.
1. Endoneurium
2. Perineurium
3. Mesoneurium
4. External epineurium

Answer 36

1—i, 2—f, 3—a, 4—d

Question 37

Neurotoxins and other agents:
a. 3,4-Methylenedioxy-methamphetamine
b. Botulinum toxin
c. Bungarotoxin
d. Curare
e. Chlorotoxin
f. Conotoxin
g. Ethanol
h. Phencyclidine (PCP)
i. Tetraethylammonium (TEA)
j. Tetrodotoxin (TTX)

For each of the following descriptions, select the
most appropriate answers from the list above.
Each answer may be used once, more than once
or not at all.
1. Uncompetitive NMDA receptor antagonist
producing dissociative state
2. Works by presynaptic competitive reuptake
inhibition followed by inhibition of VMAT
and TAAR1 receptor resulting in synaptic
accumulation of monoamines.
3. Neurotoxic peptides isolated from venom
of marin cone snail.
4. Blocker of voltage-gated K+ channels and
competitive inhibitor of nicotinic AChRs
5. Blocker of voltage-gated Na+ channels
found in Pufferfish

Answer 37

1—h, PCP; 2—a, 3,4-methylenedioxy-methamphetamine; 3—f, Conotoxin; 4—i, Tetraethylammonium (TEA); 5—j,
Tetrodotoxin (TTX)

Question 38

48. Sensory receptors:
    a. Free nerve endings
    b. Golgi tendon organs
    c. Meissner’s corpuscles
    d. Merkel’s tactile discs
    e. Nuclear bag fibers
    f. Nuclear chain fibers
    g. Pacinian corpuscles
    h. Pain nociceptors
    i. Peritrichial nerve endings
    j. Ruffini’s organs

For each of the following descriptions, select the
most appropriate answers from the list above.
Each answer may be used once, more than once
or not at all.
1. Signal the onset of muscle stretch via Aalpha myelinated fibers
2. Two-point discriminative fine touch
3. Deep pressure and vibration sense

Answer 38

1—e, Nuclear bag fibers; 2—c, Meissner’s
corpuscles; 3—g, Pacinian corpuscles

Question 39

CNS cells:
a. Astrocytes
b. Basket cells
c. Betz cells
d. Ependymal cells
e. Golgi type 2 cells
f. Granule cells
g. Martinotti cells
h. Microglia
i. Oligodendroglia
j. Purkinje cells
k. Schwann cells
l. Stellate cells

For each of the following descriptions, select the
most appropriate answers from the list above.
Each answer may be used once, more than once
or not at all.
1. These cells are derived from neural crest
origin and myelinate neurons of the PNS
2. These cells arise from monocytes (hematopoietic precursor) and thus are the resident
macrophages of the CNS. Their function is
to protect the CNS. When the brain is
damaged or infected, they become activated and multiply quickly to perform
functions such as phagocytosis and presenting antigen
3. These cells myelinate neurons within the
CNS (one cell myelinates multiple neurons).
4. These are the most abundant and largest of
the glial subtypes. Their most notable role
is the metabolism and recycling of certain
neurotransmitters (glutamate, serotonin,
and gamma-aminobutyric acid [GABA]).
They also buffer the extracellular potassium
concentration, respond to injury (gliosis),
and make up the blood-brain barrier
5. These ciliated cells line the cavities of the
CNS (ventricular system) in the choroid
plexus, where they are involved in the production of cerebrospinal fluid (CSF) and are
part of the blood-CSF barrier

Answer 39

1—k, Schwann cells; 2—h, Microglia; 3—i,
Oligodendrocytes; 4—a, Astrocytes; 5—d,
Ependymal cells

Question 40

Cerebellum:

For each of the following descriptions, select the
most appropriate answers from the image above.
Each answer may be used once, more than once
or not at all.
1. Posterior lobe
2. Flocculus
3. Primary fissure
4. Dentate nucleus
5. Anterior inferior cerebellar artery

Answer 40

1—l, 2—o, 3—k, 4—d, 5—h

Question 41

Cerebellar cortex:
For each of the following descriptions, select the
most appropriate answers from the image above.
Each answer may be used once, more than once
or not at all.
1. Purkinje cell axon
2. Basket cell
3. Climbing fiber
4. Golgi cell
5. Parallel fiber

Answer 41

1—m, 2—d, 3—k, 4—a, 5—g

Question 42

Hypothalamic-pituitary axis:
a. ACTH
b. ADH (vasopressin)
c. Cortisol
d. Epinephrine
e. FSH/LH
f. GH
g. TSH
h. Oestradiol
i. Oxytocin
j. Prolactin
k. Testosterone

For each of the following descriptions, select the
most appropriate answers from the list above.
Each answer may be used once, more than once
or not at all.
1. Uterine contractions in labor and milk ejection reflex
2. Renal water conservation
3. Excess may cause galactorrhea

Answer 42

1—i, Oxytocin; 2—b, ADH (Vasopressin); 3—j, Prolactin

Question 43

Peripheral nerve:
The internal structure of a peripheral nerve

For each of the following descriptions, select the
most appropriate answers from the image above.
Each answer may be used once, more than once
or not at all.
1. Endoneurium
2. Perineurium
3. Mesoneurium
4. External epineurium

Answer 43

1—i, 2—f, 3—a, 4—d

Question 44

Neurotransmitters:
a. Acetylcholine
b. Dopamine
c. Epinephrine
d. GABA
e. Glutamate
f. Glycine
g. Histamine
h. L-DOPA
i. Met-enkephalin
j. Serotonin
k. Substance P
l. Taurine
m. Tyramine
n. VIP

For each of the following descriptions, select the
most appropriate answers from the list above.
Each answer may be used once, more than once
or not at all.
1. The immediate precursor of norepinephrine
2. The immediate precursor of dopamine
3. Rate limiting step in the production of this
neurotransmitter is tryptophan hydroxylase
activity
4. Phenylethanolamine-N-methyl transferase
is required for production of this
transmitter
5. Required in addition to glutamate for
co-activation of NMDA receptor, but acts
as an inhibitory neurotransmitter via Cl
channels

Answer 44

1—b,Dopamine.The conversion of dopamine
to norepinephrine comes about by the action of
the enzyme dopamine #-hydroxylase
2—h, L-DOPA. The biosynthesis of catecholamines includes the following steps: tyrosine
is converted into L-dihydroxyphenylalanine
(L-DOPA) by tyrosine hydroxylase.
L-DOPA is then decarboxylated by a decarboxylase to form dopamine (and CO2)
3—j, Serotonin. Tryptophan is converted to
5-hydroxytryptophan by tryptophan
hydroxylase and by 5-hydroxytryptophan
decarboxylase into serotonin
4—c, Epinephrine. Norepinephrine is
converted into epinephrine by
phenylethanolamine-N-methyl transferase
5—f, Glycine

Question 45

Which one of the following statements concerning the resting membrane potential is most accurate?
a. Maintenance of the resting membrane potential is an energy dependent process requiring Na/K-ATPase
b. A membrane is depolarized when there is
an increase in separation of the charge across it from baseline
c. Neurons become depolarized when the charge inside the cell becomes more negative compared to its resting state
d. Hyperpolarization of a cell membrane occurs when the outside of the cell becomes more negatively charged compared to its resting state
e. Resting potential difference across a membrane is not dependent on the separation of charged ions across it

Answer 45

a. Maintenance of the resting membrane potential is an energy dependent process requiring Na/K-ATPase

Question 46

Which one of the following statements regarding the concentration of ions in extracellular and intracellular compartments is
LEAST accurate?
a. Extracellular sodium ion concentration is
approximately 140 mM (140 mEq/l)
b. Intracellular potassium ion concentration
is approximately 160 mmol/l (160 mEq/L)
c. Extracellular chloride ion concentration is
approximately 110 mM (110 mEq/l)
d. Intracellular calcium ion concentration is approximately 2 mM (4 mEq/l)
e. Extracellular bicarbonate ion concentration is approximately 22-26 mmol/l

Answer 46

d. Intracellular calcium ion concentration is approximately 2 mM (4 mEq/l)