NOCICEPTION/ PAIN EXAM NOTES: PART ONE: INTRO TO PAIN…
1. What are the four main benefits of pain?
The four main benefits of pain include inducing withdrawal reflexes to minimise
damage, learning patterns (learning to avoid), promotion of healing and
motivation to seek treatment (persistent pain, tending to the wound).
2. Does nociception perform multiple functions and in its absence would be
detrimental to one’s health and survival?
Yes! Without pain perception the individual might unknowingly procure wounds,
or injuries of high impact and not seek help/treatment, tend to the wound or
notice the damage.
3. What are four example of different key dimensions of pain?
Pain is multidimensional. These dimensions include sensory pain, emotional
pain, autonomic pain and some motor components. This experience of pain
is completely individualised, and unique to everyone.
Secondary interpretation of the dimensions: How can it be described>
Intensity, character, time, location, effect, and behaviour.
4. What are three broad classifications of pain?
There are three broad classes, and within those there are damage classes, these
can all be acute or chronic damage depending on the wound. (1) Nociceptive
pain- this pain from physical damage or potential damage to the body. It is
ADAPTIVE and HIGH THRESHOLD. There are three damage classes in nociceptive
pain: Superficial somatic (skin- triggered by sharp stimuli, well-defined easy to
locate), deep somatic pain (muscle, joint, ligaments, blood vessels, triggers a
dull aching pain, difficult to localise) and visceral pain (pain originating from
internal organs, leads to a dull, deep and squeezing pain, difficult to localise,
distant from skin). (2) Inflammatory pain- This is pain associated with tissue
injury and peripheral inflammation, it is ADAPTIVE AND LOW THRESHOLD, can
often present with spontaneous pain and pain hypersensitivity as a result. (3)
Pathological pain- This is MALADAPTIVE WITH LOW THRESHOLDS and is caused
by a diseased state. Sub types of pathological pain include neuropathic—from
damaged nerves, phantom pain—loss of a limb, and psychogenic pain—caused -
from a mental, behavioural or emotional state.
5. Why is pathological pain considered maladaptive?
Because it persists post tissue damage, where there is no apparent injury
and serves no protective function.
6. Does nociceptive pain require tissue damage?
No, it can be triggered by potential damage that if not tended too could evolve
into a more detrimental pathological pain, or a wound of greater damage.
, Pain type: What is it: Threshold + Subcategories:
adaptivity.
Nociceptive The reception of High Superficial Somatic,
harmful or threshold, Deep somatic and
potentially adaptive. visceral.
harmful stimuli.
Inflammatory The pain Low threshold, Spontaneous pain,
associated with a adaptive. pain
tissue injury or hypersensitivity.
peripheral Allodynia and
inflammation. hyperalgesia
associated
Pathological The ongoing pain Low threshold, Neuropathic,
post removal of maladaptive phantom limb and
the harmful (does not psychogenic.
stimulus, change
persistent intensity)
unpleasant pain.
7. What is allodynia and hyperalgesia, and what is the benefit of it being
adaptive over maladaptive?
Allodynia is the perception of a stimuli that is not normally painful as being
painful, whereas hyperalgesia is an increased sensitivity to pain from a stimulus
that doesn’t normally evoke pain. These two together promote repair in their
adaptive mechanism, as it means the problem is still present, and pain remains,
and when problem recedes so does the pain.
a. Also have dysaesthesia: this is defined by as an unpleasant
abnormal sensation which can either be spontaneous of evoked.
8. What is the IASP definition for pain? How is this different to nociception?
The IASP definition says that pain is an unpleasant emotional OR sensory
experience associated with or resembling that associated with actual or potential
tissue damage. Whereas, nociception is the neural process of encoding noxious
stimuli, which is damaging or threatening damage to the normal tissue. Two key
differences between the two: pain can be emotional such as feeling hurt from
a breakup, but nociception is the chemical signal that is responding to stimulus
from receptors. Pain is more complex and involves more layers to experience
than nociception.
9. What is the normal pain pathway?
CONDUCTION &
NOXIOUS STIMULI TRANSDUCTION (2), TRANSMISSION (3),
(1), A stimulus that is Reception by a high done by nociceptors,
damaging or threshold nociceptor peripheral and central
threatening to the that can transduce and neurons encoding the
body encode the noxious stimuli
stimuli.
PERCEPTION (6),
final layer of pain, MODULATION (5), MOTOR PATHWAY
becomes The regulation of the ACTIVATION (4), The
multidimensional, signal via descending relay response of the
conscious sensation. pain pathways. body in response the
stimuli.
, PART TWO: ASCENDING PATHWAYS…
1. Identify 3 nociceptive stimuli…
Three examples of nociceptive stimuli include, mechanical, thermal and
chemical, these have corresponding receptors that perceive one or more than
one of these stimuli. Nociceptive receptors are high threshold and have an all or
nothing principle (on or off) and are electrically silent at baseline. They have
many transmembrane channels and receptors for transducing a plethora of
noxious stimuli.
a. Types of nociceptors
a. Mechanical.
b. Chemical.
c. Mechano-thermal.
d. Mechano-chemo-thermal (polymodal).
e. Silent.
2. Are nociceptors always specific to one kind of noxious
stimulus?
No, there are many cross overs in pathways and perception, many are
polymodal, receiving more than one input from a stimulus at a time.
3. What kind of nerve endings do nociceptive neurons
have?
They have free nerve endings, interspersed into the skin to maximise
transduction and perceptions.
4. What are two unique properties of silent nociceptors?
They have a LOW THRESHOLD, and will not respond UNLESS
actual injury has occurred, this means they have a specialised
response, not responding to any threshold, they will respond to
inflammation of tissue.
5. Name three chemical mediators associated with tissue
injury + what is the “axon reflex” + what is released,
and what neurons are involved?
Three chemical mediators released during tissue injury are:
PROSTAGLANDIN, HISTAMINE, and BRADYKININ (there is also, ATP, K+,
serotonin and H+), these specifically are released from damaged cells.
These create responses from receptors on nociceptors, either
sensitise the nociceptors or activate silent nociceptors.
This leads to the AXON REFLEX, which is the efferent output from the nociceptor
to amplify, broaden and spread to neighbouring tissue to enact relevant
physiological change for further protection. The acting compounds include
substance P and CGRP, which when released from the nociceptor, lead to
1. What are the four main benefits of pain?
The four main benefits of pain include inducing withdrawal reflexes to minimise
damage, learning patterns (learning to avoid), promotion of healing and
motivation to seek treatment (persistent pain, tending to the wound).
2. Does nociception perform multiple functions and in its absence would be
detrimental to one’s health and survival?
Yes! Without pain perception the individual might unknowingly procure wounds,
or injuries of high impact and not seek help/treatment, tend to the wound or
notice the damage.
3. What are four example of different key dimensions of pain?
Pain is multidimensional. These dimensions include sensory pain, emotional
pain, autonomic pain and some motor components. This experience of pain
is completely individualised, and unique to everyone.
Secondary interpretation of the dimensions: How can it be described>
Intensity, character, time, location, effect, and behaviour.
4. What are three broad classifications of pain?
There are three broad classes, and within those there are damage classes, these
can all be acute or chronic damage depending on the wound. (1) Nociceptive
pain- this pain from physical damage or potential damage to the body. It is
ADAPTIVE and HIGH THRESHOLD. There are three damage classes in nociceptive
pain: Superficial somatic (skin- triggered by sharp stimuli, well-defined easy to
locate), deep somatic pain (muscle, joint, ligaments, blood vessels, triggers a
dull aching pain, difficult to localise) and visceral pain (pain originating from
internal organs, leads to a dull, deep and squeezing pain, difficult to localise,
distant from skin). (2) Inflammatory pain- This is pain associated with tissue
injury and peripheral inflammation, it is ADAPTIVE AND LOW THRESHOLD, can
often present with spontaneous pain and pain hypersensitivity as a result. (3)
Pathological pain- This is MALADAPTIVE WITH LOW THRESHOLDS and is caused
by a diseased state. Sub types of pathological pain include neuropathic—from
damaged nerves, phantom pain—loss of a limb, and psychogenic pain—caused -
from a mental, behavioural or emotional state.
5. Why is pathological pain considered maladaptive?
Because it persists post tissue damage, where there is no apparent injury
and serves no protective function.
6. Does nociceptive pain require tissue damage?
No, it can be triggered by potential damage that if not tended too could evolve
into a more detrimental pathological pain, or a wound of greater damage.
, Pain type: What is it: Threshold + Subcategories:
adaptivity.
Nociceptive The reception of High Superficial Somatic,
harmful or threshold, Deep somatic and
potentially adaptive. visceral.
harmful stimuli.
Inflammatory The pain Low threshold, Spontaneous pain,
associated with a adaptive. pain
tissue injury or hypersensitivity.
peripheral Allodynia and
inflammation. hyperalgesia
associated
Pathological The ongoing pain Low threshold, Neuropathic,
post removal of maladaptive phantom limb and
the harmful (does not psychogenic.
stimulus, change
persistent intensity)
unpleasant pain.
7. What is allodynia and hyperalgesia, and what is the benefit of it being
adaptive over maladaptive?
Allodynia is the perception of a stimuli that is not normally painful as being
painful, whereas hyperalgesia is an increased sensitivity to pain from a stimulus
that doesn’t normally evoke pain. These two together promote repair in their
adaptive mechanism, as it means the problem is still present, and pain remains,
and when problem recedes so does the pain.
a. Also have dysaesthesia: this is defined by as an unpleasant
abnormal sensation which can either be spontaneous of evoked.
8. What is the IASP definition for pain? How is this different to nociception?
The IASP definition says that pain is an unpleasant emotional OR sensory
experience associated with or resembling that associated with actual or potential
tissue damage. Whereas, nociception is the neural process of encoding noxious
stimuli, which is damaging or threatening damage to the normal tissue. Two key
differences between the two: pain can be emotional such as feeling hurt from
a breakup, but nociception is the chemical signal that is responding to stimulus
from receptors. Pain is more complex and involves more layers to experience
than nociception.
9. What is the normal pain pathway?
CONDUCTION &
NOXIOUS STIMULI TRANSDUCTION (2), TRANSMISSION (3),
(1), A stimulus that is Reception by a high done by nociceptors,
damaging or threshold nociceptor peripheral and central
threatening to the that can transduce and neurons encoding the
body encode the noxious stimuli
stimuli.
PERCEPTION (6),
final layer of pain, MODULATION (5), MOTOR PATHWAY
becomes The regulation of the ACTIVATION (4), The
multidimensional, signal via descending relay response of the
conscious sensation. pain pathways. body in response the
stimuli.
, PART TWO: ASCENDING PATHWAYS…
1. Identify 3 nociceptive stimuli…
Three examples of nociceptive stimuli include, mechanical, thermal and
chemical, these have corresponding receptors that perceive one or more than
one of these stimuli. Nociceptive receptors are high threshold and have an all or
nothing principle (on or off) and are electrically silent at baseline. They have
many transmembrane channels and receptors for transducing a plethora of
noxious stimuli.
a. Types of nociceptors
a. Mechanical.
b. Chemical.
c. Mechano-thermal.
d. Mechano-chemo-thermal (polymodal).
e. Silent.
2. Are nociceptors always specific to one kind of noxious
stimulus?
No, there are many cross overs in pathways and perception, many are
polymodal, receiving more than one input from a stimulus at a time.
3. What kind of nerve endings do nociceptive neurons
have?
They have free nerve endings, interspersed into the skin to maximise
transduction and perceptions.
4. What are two unique properties of silent nociceptors?
They have a LOW THRESHOLD, and will not respond UNLESS
actual injury has occurred, this means they have a specialised
response, not responding to any threshold, they will respond to
inflammation of tissue.
5. Name three chemical mediators associated with tissue
injury + what is the “axon reflex” + what is released,
and what neurons are involved?
Three chemical mediators released during tissue injury are:
PROSTAGLANDIN, HISTAMINE, and BRADYKININ (there is also, ATP, K+,
serotonin and H+), these specifically are released from damaged cells.
These create responses from receptors on nociceptors, either
sensitise the nociceptors or activate silent nociceptors.
This leads to the AXON REFLEX, which is the efferent output from the nociceptor
to amplify, broaden and spread to neighbouring tissue to enact relevant
physiological change for further protection. The acting compounds include
substance P and CGRP, which when released from the nociceptor, lead to
