Pain and Nociception Flashcards
What is the difference between Pain and Nociception
Pain = Subjective response Nociception = Physiological response
Some types of pain serve no useful purpose. Give such examples of pain
Chronic pain Rheumatic pain Cancer pain Neuropathic pain Amputation pain
How can you characterise pain based on origin
Somatic pain (Superficial + Deep) Visceral pain
Visceral pain affects where in the body?
Organs of the thorax and abdominal cavity
How can you characterise pain based on duration
Acute (normal pain)
Chronic pain
Chronic pain has what kind of duration?
> 3 months
What receptors detect pain, and along what neurone to they travel to get to the CNS
Nociceptors
Travel along the primary afferent fibre through the Dorsal Route Ganglion into the spinal cord, specifically the dorsal horn
Noiceptors are sensors found on most body tissues, and consist of…?
Unspecialised nerve cell endings or “free nerve endings”
What are the five different types of nociceptors
Thermal Mechanical Chemical Polymodal Sleeping / Silent
Polymodal receptors are a combination of what 3 Nociceptors
Thermal
Mechanical
Chemical
What are the four types of Primary afferent fibres
Aa
Ab
Ad
C
Low threshold mechanoreceptors have what class of Primary Afferent Fibre?
Aa and Ab
Which primary afferent fibres are slow conducting and small diameter?
Ad and C
Polymodal nociceptors have which fibres?
C
First and second pain is characterised by which fibres?
Ad and C
First pain is described as what?
Sharp / prickling
Are C fibres myelinated or unmyelinated?
Unmyelinated
Second pain is described as what?
Dull, aching and burning
How is congenital analgesia caused?
Mutation in genes encoding Na+ channels
What is congenital analgesia?
They have an inability to feel pain
C fibres terminate in which Lamina?
Lamina II
Ad fibres terminate in which Lamina?
Lamina I
Nociceptive Pathway follows which tract?
The spinothalamic tract
The spinothalamic tract / nociceptive pathway decussates and is relayed via _________ to the _______ to the ________?
Via medulla to thalamus to somatosensory cortex
The main neurotransmitters involved in Nociception are what?
Glutamate and Substance P
How is referred pain caused?
Caused by convergence of nociceptor inputs from the viscera and skin
What does the Gate theory explain?
Why pain is reduced by stimulating mechanoreceptors, i.e. rubbing your knee after falling over
What is allodynia?
Touch-evoked pain when it normally shouldn’t
What is hyperalgesia?
Increased pain sensation from something which usually causes only a little pain
What is primary and secondary hyperalgesia?
Primary = occurs in the site of tissue damage
Secondary = occurs around the site of tissue damage
Give four examples of pharmacological interventions used to treat pain
Opiods
NSAIDs
Local anaesthetics
Psychotropic drugs
What is a rhizotomy?
Cutting of dorsal roots, is a surgical intervention
Give examples of three endogenous opiods
Endorphins
Enkephalins
Dynorphins
What are the three types of opiod receptors?
Mu
Delta
Kappa
What is Naloxone?
An opiod selective receptor antagonist. Used to reverse opiod induced respratory depression and opiod overdose
