Chapter 2. Pain Physiology Flashcards
1
Q
46. Which of the following nerves conduct nociceptive stimuli? (A) A-δ fibers and C fibers (B) A-δ fibers and A-β fibers (C) A-β fibers and C fibers (D) B fibers and C fibers (E) A-α fibers and A-β fibers
A
- (A) Nociceptors transmit impulses mainly
through the A-δ and C fibers to the spinal cord.
A-β fibers carry impulses generated from lowthreshold
mechanoceptors. B fibers are mainly
preganglionic autonomic (white rami and cranial
nerves III, VII, IX, X).
2
Q
- Arrange A-δ, A-β, B, C, and A-α nerves according
to their conduction velocity (fastest to slowest):
(A) A-α, A-β, A-δ, B, C
(B) A-δ, C, B, A-β, A-α
(C) C, B, A-δ, A-β, A-α
(D) A-β, A-δ, C, B, A-α
(E) B, C, A-β, A-α, A-δ
A
- (A) Conduction velocity is dependent on the
size of the nerve fiber as well as myelination.
Myelinated nerves conduct the impulse faster
than unmyelinated nerves (C) due to jumping
from one node to the next node of Ranvier
(saltatory conduction).
3
Q
48. The impulse traveling through the C fiber terminates in the Rexed laminae: (A) Laminae 1 and 5 (B) Laminae 1 and 2 (C) Laminae 1, 2, and 5 (D) Laminae 2 and 5 (E) Laminae 3 and 5
A
- (C) Impulses C fibers and their collaterals terminate
in the Rexed laminae L1, L2, and L5.
4
Q
- Some of the naturally occurring chemicals
involved in nociceptive input are hydrogen
ions, serotonin (5-HT), and bradykinin. What
effect do these have on the nociceptors?
(A) Sensitize the nociceptors
(B) Activate the nociceptors
(C) Activate and sensitize the nociceptors
(D) Block the nociceptors
(E) Modify the nociceptors
A
- (B) The sensitization of nociceptors may be
caused by prostaglandins and cytokines, whereas
activation is caused by substance, such as
hydrogen ions, serotonin, and bradykinin.
5
Q
50. Substance P release from the dorsal horn neuronal elements is blocked by (A) endogenous opioids (B) exogenous opioids (C) both type of opioids (D) anticonvulsant medications (E) local anesthetics
A
- (C) Both, endogenous as well as exogenous
opioids block the release of substance P in the
dorsal horn there by providing analgesia.
6
Q
- Arrange the visceral structures—hollow viscera,
solid viscera, serosal membranes—in the order
of increasing sensitivity to noxious stimuli:
(A) Serosal membranes, hollow viscera, solid viscera
(B) Hollow viscera, solid viscera, serosal membranes
(C) Solid viscera, hollow viscera, serosalmembranes
(D) Hollow viscera, serosal membranes,solid viscera
(E) Serosal membranes, solid viscera, hollow viscera
A
- (C) The serosal membranes are the most sensitive
and the solid viscera the least sensitive to
noxious stimuli.
7
Q
52. Visceral pain is typically felt as (A) dull (B) sharp (C) vague (D) all of the above (E) A and C only
A
- (E) The visceral pain is felt as a vague, deep,
dull pain as opposed to sharp and well-defined
pain. It may mimic other
8
Q
53. Hollow viscera can be painful during which type of contractions? (A) Isotonic (B) Isometric (C) Sustained (D) Isotonic and isometric (E) None of the above
A
- (B) Viscera can generate painful contraction in
an isometric contraction state such as bowel
and ureteral obstruction. Isotonic contractions
usually are not painful.
9
Q
- Certain nociceptors are termed “silent nociceptors.”
These can be activated (“awakened”)
by a prolonged noxious stimulus, such as
inflammation. These types of receptors were
initially identified in which structures?
(A) Bones
(B) Brain
(C) Nails
(D) Joints
(E) Nerves
A
- (D) Sleeping or silent nociceptors are population
of nociceptors that remain inactive under
normal conditions. They are activated because
of tissue injury, with consequent release of
chemical mediators. They appear to be present
in skin, joints, muscle, and visceral tissue.
10
Q
55. Visceral referred pain with hyperalgesia can be explained by which of the following? (A) Viscerovisceral convergence (B) Viscerosomatic convergence (C) Nociceptive perception (D) Sympathetic stimulation (E) Sympathetic transmission
A
- (B) The viscerosomatic convergence of signals
within the spinal cord at the level of dorsal
horn and at supraspinal levels within the
brainstem, thalamus, and cortex; explains the
phenomenon of referred pain to somatic structures.
Viscerovisceral convergence on the other
hand has been shown to exist between
colon/rectum, bladder, vagina, and uterine
cervix, and between heart and gallbladder.
11
Q
56. Enkephalins and somatostatin – are these types of neurotransmitters: (A) Excitatory (B) Inhibitory (C) Gastrotransmitters (D) Excitatory and inhibitory (E) None of the above
A
- (B) Dopamine, epinephrine, and norepinephrine
are considered to be excitatory neurotransmitters,
whereas serotonin, GABA, and dopamine
are the other inhibitory neurotransmitters.
12
Q
57. There are several subtypes of N-methyl-Daspartate (NMDA) receptors. They are (A) NR1, NR2 (A, B, and C) (B) NR1, NR2 (A, B, C, and D) (C) NR1, NR2 (A, B, and C), and NR3 (A and B) (D) NR1, NR2 (A, B, C, and D), and NR3 (A and B) (E) NR1, NR2 (A, B, C, and D), NR3 (A and B), and NR4 (A and B)
A
- (D) There is accumulating evidence to implicate
the importance of NMDA receptors to the
induction and maintenance of central sensitization
during pain states. However, NMDA
receptors may also mediate peripheral sensitization
and visceral pain. NMDA receptors are
composed of NR1, NR2 (A, B, C, and D), and
NR3 (A and B) subunits, which determine the
functional properties of native NMDA receptors.
Among NMDA receptor subtypes, the
NR2B subunit– containing receptors appear particularly
important for nociception, thus leading to the possibility that NR2B-selective antagonists
may be useful in the treatment of chronic pain.
13
Q
58. Sodium channels are also important in neurotransmission through the dorsal root ganglion (DRG). How many different types of sodium channels have been identified? (A) Four (B) Eight (C) Seven (D) Five (E) Nine
A
- (E) Voltage-gated sodium channels underlie
the electrical excitability demonstrated by
mammalian nerve and muscle. Nine voltagegated
sodium channels are expressed in complex
patterns in mammalian nerve and muscle.
Six have been identified in the DRG. Three
channels, Nav1.7, Nav1.8, and Nav1.9, are
expressed selectively in peripheral damagesensing
neurons. Nav1.8 seems to play a specialized
role in pain pathways.
14
Q
59. Ziconotide, found in snail venom, acts primarily on which type of calcium channel? (A) N-type (B) T-type (C) L-type (D) P-type (E) Q-type
A
- (A) The nonopioid analgesic ziconotide has been
developed as a new treatment for patients with
severe chronic pain who are intolerant of and/or
refractory to other analgesic therapies. Ziconotide
is the synthetic equivalent of a 25-amino-acid
polybasic peptide found in the venom of the
marine snail Conus magus. In rodents, ziconotide
acts by binding to neuronal N-type voltagesensitive
calcium channels, thereby blocking
neurotransmission from primary nociceptive
afferents. Ziconotide produces potent antinociceptive
effects in animal models and its efficacy
has been demonstrated in human studies.
15
Q
- Pretreatment with an NMDA antagonist prior to inflammation has been shown to
(A) enhance central sensitization
(B) attenuate central sensitization
(C) have no effect on central sensitization
(D) enhance peripheral sensitization
(E) attenuate peripheral sensitization
A
- (B) Pretreatment with an NMDA antagonist
attenuates the central sensitization from inflammation.
16
Q
- NMDA receptor channels are usually inactive
and blocked by zinc and magnesium ions.
Adepolarization of the cell membrane removes
these ions and allows influx of which ions?
(A) Sodium
(B) Calcium
(C) Chloride
(D) Sodium and calcium
(E) Sodium and chloride
A
- (D) NMDA receptor ion channel has binding
sites for zinc, magnesium, and phencyclidine,
which are inhibitory. A depolarization causes
removal of zinc and magnesium allowing
largely calcium and to much lesser extent
sodium ions to influx, initiating intracellular
activity.
17
Q
- Nociceptive stimuli cause increased activity in
the cerebral cortex in
(A) a focal area around the central gyrus
(B) widespread areas in the temporal cortex
(C) a focal area around the posterior cortical
areas
(D) widespread areas in the frontal cortex
(E) a focal area in the thalamus
A
- (B) Noxious stimuli cause widespread activation
of cortical area. Increasing stimulus intensity
activates increasing number of areas within
the cortex. Other areas of the brain are not
involved in the interpretation of the noxious
stimuli.
18
Q
63. γ-Aminobutyric acid (GABA) receptors (a type of cellular channel), are these types of ion channels: (A) Calcium (B) Sodium (C) Chloride (D) Magnesium (E) Potassium
A
- (C) Three major classes of chloride channels
have been identified. The first class identified
was the ligand-gated chloride channels, including
those of the GABAA and glycine receptors.
The ligand-gated chloride channels are common
in dorsal horn neurons. The second class, also
likely common spinal levels, is the voltage-gated
chloride channels. The final chloride channel
class is activated by cyclic adenosine monophosphate
and may include only the cystic fibrosis
transmembrane regulator. Activation of chloride
currents usually produces inward movement
of chloride to cells that hyperpolarize
neurons; facilitation of these hyperpolarizing
currents underlies the mechanisms of many
depressant drugs. An important exception at
spinal levels, however, is that GABAA receptors
on primary afferent terminals gate a chloride
channel that allows reflux of chloride with a net
effect therefore of depolarizing primary afferent
terminals.
