Nociceptors and Pain
Objectives
Definition and calassificaiiton of nocirepcepts
physiological efects and basic mechanisms in nociception
explain how nociceptor function may be regulated and the
roles of ion channels
voltage and ligand dated and metabotropic receptors in
these processes
types and classes of pain (receptors) - fast vs slow pain
chemicals involved in pain transmission
afferent pathways of pain
Nociception
painful conscious sensations
pain is the perception of an aversive or unpleasant sensation
that originations from a specific region of the body
Manifestations of pain
hyperalgesia - severe pain from a stimulus that would
normally cause only slight discomfort
paresthesia - unpleasant or painful feelings eg. pins and
needles
allodynia
hyperpathia
Why do we feel pain?
gives conscious awareness of tissue damage
protection
Nociceptors and Pain 1
, remove the body from danger
promote healing by preventing further damage
avoid noxious stimuli that would cause damage ot the
body
elicits different emotional and behavioural responses
Pain can be modified by:
past experiences - different kind of reaction from a pain
that you had in the past compared to when you get a new
pain
suggestion - eg. if persons tell you that boys will hurt
you, you tend to stay away from all boys
emotion - particularly by anxiety or based on the person's
current emotional status
simultaneous activation of other sensory modulaties. this
is the basis of the gate theory
different state of attention
Pain stimulates:
sympathetic nervous system
hypertension, vasoconstriction, tachycardia, mydriasis,
sweating
parasympathetic nervous system
nausea, bradycardia, hypotension, disturbances of
consciousness, vomiting
respiration and cardiovascular reflexes
endocrine response
motor response
Nociceptors and Pain 2
, escape, changes in muscle tone
Types of pain
different ways of classification of pain
by perception: fast/sharp pain and slow
somatic and visceral pain
superficial and deep pain
physiological sharp pain and pathological pain
(inflammatory, neuropathic pain)
Nociceptors
these receptors are able convert the stimuli to electrical
potential
majority of these receptors are free nerve endings
they are widespread in the superficial layers of the skin as
well as in certain internal tissues such as the periosterum,
arterial walls, joint surfaces and falx and tentorium in
cranial vault
A delta fibres: mainly project to laminae I and V
C fibres: project to laminae I, II (interneurones that contact
both spinothalamic and spinoparabrachial systems) and V
A fibers carry fast pain
C fibers carry slow pain
Types of nocireceptors
Mechanial nociceptors
Nociceptors and Pain 3
Objectives
Definition and calassificaiiton of nocirepcepts
physiological efects and basic mechanisms in nociception
explain how nociceptor function may be regulated and the
roles of ion channels
voltage and ligand dated and metabotropic receptors in
these processes
types and classes of pain (receptors) - fast vs slow pain
chemicals involved in pain transmission
afferent pathways of pain
Nociception
painful conscious sensations
pain is the perception of an aversive or unpleasant sensation
that originations from a specific region of the body
Manifestations of pain
hyperalgesia - severe pain from a stimulus that would
normally cause only slight discomfort
paresthesia - unpleasant or painful feelings eg. pins and
needles
allodynia
hyperpathia
Why do we feel pain?
gives conscious awareness of tissue damage
protection
Nociceptors and Pain 1
, remove the body from danger
promote healing by preventing further damage
avoid noxious stimuli that would cause damage ot the
body
elicits different emotional and behavioural responses
Pain can be modified by:
past experiences - different kind of reaction from a pain
that you had in the past compared to when you get a new
pain
suggestion - eg. if persons tell you that boys will hurt
you, you tend to stay away from all boys
emotion - particularly by anxiety or based on the person's
current emotional status
simultaneous activation of other sensory modulaties. this
is the basis of the gate theory
different state of attention
Pain stimulates:
sympathetic nervous system
hypertension, vasoconstriction, tachycardia, mydriasis,
sweating
parasympathetic nervous system
nausea, bradycardia, hypotension, disturbances of
consciousness, vomiting
respiration and cardiovascular reflexes
endocrine response
motor response
Nociceptors and Pain 2
, escape, changes in muscle tone
Types of pain
different ways of classification of pain
by perception: fast/sharp pain and slow
somatic and visceral pain
superficial and deep pain
physiological sharp pain and pathological pain
(inflammatory, neuropathic pain)
Nociceptors
these receptors are able convert the stimuli to electrical
potential
majority of these receptors are free nerve endings
they are widespread in the superficial layers of the skin as
well as in certain internal tissues such as the periosterum,
arterial walls, joint surfaces and falx and tentorium in
cranial vault
A delta fibres: mainly project to laminae I and V
C fibres: project to laminae I, II (interneurones that contact
both spinothalamic and spinoparabrachial systems) and V
A fibers carry fast pain
C fibers carry slow pain
Types of nocireceptors
Mechanial nociceptors
Nociceptors and Pain 3
