Double Pain Sensations
Two sequential pain sensations in short time intervals is the result of sudden painful stimulation. The first one is immediately after the damage. It is followed several seconds later with additional pain sensation. These two separate sensations are several seconds apart because a fast transmitting information sensation is carried via A delta fibers and is followed several seconds later with slow transmitting pain information carried via C fibers. This phenomenon is known as “double pain sensation” (Figure 6.9).
Two experimental procedures were used to verify which information is carried by which fibers.
- Externally applied pressure, such as compression of the skin above a nerve, first blocks the myelinated A delta fibers, while C fibers continue to conduct action potentials and allow the slow conducting pain to be carried.
- A low dose of local anesthesia applied to peripheral nerves blocks the unmyelinated C fibers before the myelinated A delta fibers. Under this condition, the slow conducting pain information is blocked, and only the fast conducting pain information by A delta fibers is carried to the CNS. This experiment provides additional evidence that two different types of nerve fibers carry noxious information.
Nociceptive Neurons in the Spinal Cord (Nocineurons)
The synaptic terminals of the axons of the dorsal root ganglion, which carry noxious information arriving to Rexed layers I and II (Figure 6.10), release neurochemical agents such as substance P (SP), glutamate, aspartate, vasoactive intestinal peptide (VIP), cholecystokinin (CCK), somatostatin, calcitonin gene-related peptide (CGRP), galanin, and other agents. These agents activate the nocineurons. It was shown that when SP and CGRP are applied locally within the spinal cord dorsal horn, glutamate is released. The release of glutamate excites the nocineurons. Furthermore, SP receptors (neurokinin receptors) and NMDA receptors (glutamate) interact which result that the NMDA receptors will become more sensitive to glutamate, which results in central sensitization. The functions of these peptides are largely unknown but they presumably mediate slow, modulatory synaptic actions in the dorsal horn neurons. The neuropeptides are always co-localized with other "classical" neurotransmitters.
There are four general types of nocineurons in the spinal cord (Figure 6.10):
- High threshold mechanoreceptor neurons or nociceptive specific neurons. These neurons are excited only by noxious cutaneous and/or visceral stimuli. The nociceptive afferent fibers release glutamate and different neuropeptides to activate the dorsal horn neurons.
- Chemical nociceptor neurons are excited by chemical or thermal noxious stimulus in the skin or in visceral organs.
- Thermal nociceptor neurons are excited by chemical or thermal noxious stimulus in the skin or in visceral organs.
- Polymodal-nociceptive neurons or multi, or wide dynamic range nociceptive neurons. These neurons are excited by both noxious and non-noxious cutaneous and/or visceral stimuli (polymodal nociceptive neurons). These neurons are activated by a variety of noxious stimuli (mechanical, thermal, chemical, etc.) and respond incrementally to increasing intensity of the stimuli.
Figure 6.10 |
Rexed lamina I contains a higher proportion of nociceptive specific neurons, whereas Rexed lamina II contains predominantly multi-receptive wide dynamic range neurons. The nociceptive-specific neurons alert the subject when a stimulus is noxious, and the multi-receptive neurons provide the subject with information about the parameters of the noxious stimulus. In general, C fibers release neuropeptides such as substance P whereas the A delta fibers release glutamate.
Classification of Pain
Pain has been classified into three major types:
- Pricking pain. Pain caused by a needle, pin prick, skin cut, etc. - elicits a sharp, pricking quality, stinging pain sensation carried fast by the A delta fibers. The pain is precisely localized and of short duration. Pricking pain is also called fast pain, first pain or sensory pain. Pricking pain is present in all individuals and is a useful and necessary component of our sensory repertoire. Without this type of protective pain sensation, everyday life would be difficult. Pricking pain arises mainly from the skin, and carried mainly by A delta fibers which permits discrimination (i.e., permits the subject to localize the pain).
- Burning pain or soreness pain. Pain caused by inflammation, burned skin, etc., is carried by the C fibers (slowly conducted pain nerve fibers). This type of pain is a more diffuse, slower to onset, and longer in duration. It is an annoying pain and intolerable pain, which is not distinctly localized. Like pricking pain, burning pain arises mainly from the skin. It is carried by the paleospinothalamic tract. (The old primitive transmission system for diffuse pain which does not permit exact localization.)
- Aching pain is a sore pain. This pain arises mainly from the viscera and somatic deep structures. Aching pain is not distinctly localized and is an annoying and intolerable pain. Aching pain is carried by the C fibers from the deep structures to the spinal cord.
- Question 1
- A
- B
- C
- D
- E
All of the following are released in response to noxious stimulation at the damaged site(s) EXCEPT:
A. Globulin
B. Dopamine
C. Arachnoid Acid
D. Acetylcholine
E. Histamine
All of the following are released in response to noxious stimulation at the damaged site(s) EXCEPT:
A. Globulin This answer is INCORRECT.
B. Dopamine
C. Arachnoid Acid
D. Acetylcholine
E. Histamine
All of the following are released in response to noxious stimulation at the damaged site(s) EXCEPT:
A. Globulin
B. Dopamine This answer is CORRECT!
Dopamine is not released in response to noxious stimulation.
C. Arachnoid Acid
D. Acetylcholine
E. Histamine
All of the following are released in response to noxious stimulation at the damaged site(s) EXCEPT:
A. Globulin
B. Dopamine
C. Arachnoid Acid This answer is INCORRECT.
D. Acetylcholine
E. Histamine
All of the following are released in response to noxious stimulation at the damaged site(s) EXCEPT:
A. Globulin
B. Dopamine
C. Arachnoid Acid
D. Acetylcholine This answer is INCORRECT.
E. Histamine
All of the following are released in response to noxious stimulation at the damaged site(s) EXCEPT:
A. Globulin
B. Dopamine
C. Arachnoid Acid
D. Acetylcholine
E. Histamine This answer is INCORRECT.
- Question 2
- A
- B
- C
- D
- E
C fibers transmit which type of pain?
A. Pricking pain
B. Stimulation produced analgesia
C. Referred pain
D. Burning pain
E. Sharp pain
C fibers transmit which type of pain?
A. Pricking pain This answer is INCORRECT.
B. Stimulation produced analgesia
C. Referred pain
D. Burning pain
E. Sharp pain
C fibers transmit which type of pain?
A. Pricking pain
B. Stimulation produced analgesia This answer is INCORRECT.
C. Referred pain
D. Burning pain
E. Sharp pain
C fibers transmit which type of pain?
A. Pricking pain
B. Stimulation produced analgesia
C. Referred pain This answer is INCORRECT.
D. Burning pain
E. Sharp pain
C fibers transmit which type of pain?
A. Pricking pain
B. Stimulation produced analgesia
C. Referred pain
D. Burning pain This answer is CORRECT!
C fibers carry the burning pain sensation.
E. Sharp pain
C fibers transmit which type of pain?
A. Pricking pain
B. Stimulation produced analgesia
C. Referred pain
D. Burning pain
E. Sharp pain This answer is INCORRECT.
- Question 3
- A
- B
- C
- D
- E
C fibers are
A. small myelinated fibers which carry sharp pain
B. large unmyelinated fibers which carry burning pain
C. small unmyelinated fibers which carry burning pain
D. large myelinated fibers which carry sharp pain
E. large myelinated fibers which carry temperature sensation
C fibers are
A. small myelinated fibers which carry sharp pain This answer is INCORRECT.
B. large unmyelinated fibers which carry burning pain
C. small unmyelinated fibers which carry burning pain
D. large myelinated fibers which carry sharp pain
E. large myelinated fibers which carry temperature sensation
C fibers are
A. small myelinated fibers which carry sharp pain
B. large unmyelinated fibers which carry burning pain This answer is INCORRECT.
C. small unmyelinated fibers which carry burning pain
D. large myelinated fibers which carry sharp pain
E. large myelinated fibers which carry temperature sensation
C fibers are
A. small myelinated fibers which carry sharp pain
B. large unmyelinated fibers which carry burning pain
C. small unmyelinated fibers which carry burning pain This answer is CORRECT!
The C fibers are unmyelinated fibers that carry burning pain.
D. large myelinated fibers which carry sharp pain
E. large myelinated fibers which carry temperature sensation
C fibers are
A. small myelinated fibers which carry sharp pain
B. large unmyelinated fibers which carry burning pain
C. small unmyelinated fibers which carry burning pain
D. large myelinated fibers which carry sharp pain This answer is INCORRECT.
E. large myelinated fibers which carry temperature sensation
C fibers are
A. small myelinated fibers which carry sharp pain
B. large unmyelinated fibers which carry burning pain
C. small unmyelinated fibers which carry burning pain
D. large myelinated fibers which carry sharp pain
E. large myelinated fibers which carry temperature sensation This answer is INCORRECT.
- Question 4
- A
- B
- C
- D
- E
Aspirin acts to block the formation of
A. Bradykinins
B. Prostaglandins
C. Histamine
D. Dopamine
E. Serotonin
Aspirin acts to block the formation of
A. Bradykinins This answer is INCORRECT.
B. Prostaglandins
C. Histamine
D. Dopamine
E. Serotonin
Aspirin acts to block the formation of
A. Bradykinins
B. Prostaglandins This answer is CORRECT!
Prostaglandins is the answer because aspirin blocks the prostaglandins release from the damaged tissue. Prostaglandins activate the nociceptors. Aspirin has no effect on other chemicals released at the damage site.
C. Histamine
D. Dopamine
E. Serotonin
Aspirin acts to block the formation of
A. Bradykinins
B. Prostaglandins
C. Histamine This answer is INCORRECT.
D. Dopamine
E. Serotonin
Aspirin acts to block the formation of
A. Bradykinins
B. Prostaglandins
C. Histamine
D. Dopamine This answer is INCORRECT.
E. Serotonin
Aspirin acts to block the formation of
A. Bradykinins
B. Prostaglandins
C. Histamine
D. Dopamine
E. Serotonin This answer is INCORRECT.
- Question 5
- A
- B
- C
- D
- E
A delta fibers transmit primarily
A. burning diffuse pain information
B. pricking localized pain information
C. aching diffuse pain information
D. visceral pain information
E. phantom pain information
A delta fibers transmit primarily
A. burning diffuse pain information This answer is INCORRECT.
B. pricking localized pain information
C. aching diffuse pain information
D. visceral pain information
E. phantom pain information
A delta fibers transmit primarily
A. burning diffuse pain information
B. pricking localized pain information This answer is CORRECT!
A delta fibers carry sharp/pricking pain, all the others are carried by C fibers.
C. aching diffuse pain information
D. visceral pain information
E. phantom pain information
A delta fibers transmit primarily
A. burning diffuse pain information
B. pricking localized pain information
C. aching diffuse pain information This answer is INCORRECT.
D. visceral pain information
E. phantom pain information
A delta fibers transmit primarily
A. burning diffuse pain information
B. pricking localized pain information
C. aching diffuse pain information
D. visceral pain information This answer is INCORRECT.
E. phantom pain information
A delta fibers transmit primarily
A. burning diffuse pain information
B. pricking localized pain information
C. aching diffuse pain information
D. visceral pain information
E. phantom pain information This answer is INCORRECT.
- Question 6
- A
- B
- C
- D
- E
Pain receptors/nociceptors are
A. bipolar cells
B. free nerve endings
C. epithelial receptors
D. Pacinian corpuscles
E. Meissner corpuscles
Pain receptors/nociceptors are
A. bipolar cells This answer is INCORRECT.
B. free nerve endings
C. epithelial receptors
D. Pacinian corpuscles
E. Meissner corpuscles
Pain receptors/nociceptors are
A. bipolar cells
B. free nerve endings This answer is CORRECT!
Only the free nerve endings are the receptors (nociceptors) that sense pain.
C. epithelial receptors
D. Pacinian corpuscles
E. Meissner corpuscles
Pain receptors/nociceptors are
A. bipolar cells
B. free nerve endings
C. epithelial receptors This answer is INCORRECT.
D. Pacinian corpuscles
E. Meissner corpuscles
Pain receptors/nociceptors are
A. bipolar cells
B. free nerve endings
C. epithelial receptors
D. Pacinian corpuscles This answer is INCORRECT.
E. Meissner corpuscles
Pain receptors/nociceptors are
A. bipolar cells
B. free nerve endings
C. epithelial receptors
D. Pacinian corpuscles
E. Meissner corpuscles This answer is INCORRECT.
- Question 7
- A
- B
- C
- D
- E
Double pain sensation results from
A. two different pain receptors
B. two different pathways, differing in the number of the synapses
C. two different fibers which conduct the impulses at different velocities
D. two different neurotransmitters
E. two different neuropeptides
Double pain sensation results from
A. two different pain receptors This answer is INCORRECT.
B. two different pathways, differing in the number of the synapses
C. two different fibers which conduct the impulses at different velocities
D. two different neurotransmitters
E. two different neuropeptides
Double pain sensation results from
A. two different pain receptors
B. two different pathways, differing in the number of the synapses This answer is INCORRECT.
C. two different fibers which conduct the impulses at different velocities
D. two different neurotransmitters
E. two different neuropeptides
Double pain sensation results from
A. two different pain receptors
B. two different pathways, differing in the number of the synapses
C. two different fibers which conduct the impulses at different velocities This answer is CORRECT!
The reason for double pain sensation is that two different fibers (A delta and C fibers) carries pain sensation at different speed.
D. two different neurotransmitters
E. two different neuropeptides
Double pain sensation results from
A. two different pain receptors
B. two different pathways, differing in the number of the synapses
C. two different fibers which conduct the impulses at different velocities
D. two different neurotransmitters This answer is INCORRECT.
E. two different neuropeptides
Double pain sensation results from
A. two different pain receptors
B. two different pathways, differing in the number of the synapses
C. two different fibers which conduct the impulses at different velocities
D. two different neurotransmitters
E. two different neuropeptides This answer is INCORRECT.
- Question 8
- A
- B
- C
- D
- E
A delta fibers transmit which type of pain to VPL?
A. Pricking pain
B. Deep pain
C. Visceral pain
D. Burning pain
E. Aching pain
A delta fibers transmit which type of pain to VPL?
A. Pricking pain This answer is CORRECT!
A delta fibers carry pricking/sharp pain. Al the other pains (deep, visceral, burning, aching) are carried via C fibers.
B. Deep pain
C. Visceral pain
D. Burning pain
E. Aching pain
A delta fibers transmit which type of pain to VPL?
A. Pricking pain
B. Deep pain This answer is INCORRECT.
C. Visceral pain
D. Burning pain
E. Aching pain
A delta fibers transmit which type of pain to VPL?
A. Pricking pain
B. Deep pain
C. Visceral pain This answer is INCORRECT.
D. Burning pain
E. Aching pain
A delta fibers transmit which type of pain to VPL?
A. Pricking pain
B. Deep pain
C. Visceral pain
D. Burning pain This answer is INCORRECT.
E. Aching pain
A delta fibers transmit which type of pain to VPL?
A. Pricking pain
B. Deep pain
C. Visceral pain
D. Burning pain
E. Aching pain This answer is INCORRECT.
- Question 9
- A
- B
- C
- D
- E
Sharp pain, induced by a skin cut for example, is classified by
A. Burning pain
B. Aching pain
C. Somatic pain
D. Pricking pain
E. Visceral pain
Sharp pain, induced by a skin cut for example, is classified by
A. Burning pain This answer is INCORRECT.
B. Aching pain
C. Somatic pain
D. Pricking pain
E. Visceral pain
Sharp pain, induced by a skin cut for example, is classified by
A. Burning pain
B. Aching pain This answer is INCORRECT.
C. Somatic pain
D. Pricking pain
E. Visceral pain
Sharp pain, induced by a skin cut for example, is classified by
A. Burning pain
B. Aching pain
C. Somatic pain This answer is INCORRECT.
D. Pricking pain
E. Visceral pain
Sharp pain, induced by a skin cut for example, is classified by
A. Burning pain
B. Aching pain
C. Somatic pain
D. Pricking pain This answer is CORRECT!
A delta fibers carry information induced by a skin cut, which is classified as a pricking pain.
E. Visceral pain
Sharp pain, induced by a skin cut for example, is classified by
A. Burning pain
B. Aching pain
C. Somatic pain
D. Pricking pain
E. Visceral pain This answer is INCORRECT.
