PAIN PATHWAYS AND GATING Flashcards
What is pain
An unpleasant sensory and emotional experience associated with or resembling that associated with actual or potential tissue
What is nociception
The reception, conduction and CNS processing of nerve signals from nociceptors resulting in the perception of pain
What might affect how pain is perceived
Descending controls from the lambic brain such as sleep, fear and anxiety
What are the 2 types of cutaneous pain
- noxious mechanical stimulus
- noxious heat and chemical stimuli
Describe noxious mechanical stimulus
- A fibre type
- usually form the first response
Describe noxious heat and chemical stimuli
- C fibre type
- responsible for the lasting pain after an injury
Describe type a nerve fibres
Myelinated
Fast conducting
Well localised sharp pain
Describe type c nerve fibres
Unmyelinated
Slow
Dull aching pain, not well localised
What are the 2 significant pain pathways
- Spinocervicothalamic tract
- Spinoreticular tract
Describe the spinocervicothalamic tract
- 3 neurons (4 in carnivores)
- associated with touch and superficial pain
- discriminatory- cant tell the exact location of pain
Describe the spinooreticular tract
- 3 neurons
- associated with deep pain and visceral sensations
- less discriminatory - cant tell exact location of the pain
- less type a fibres present in this system
What pain system is associated with the head
The trigeminal system
What are the different types of modulation in the CNS
- peripheral modulation
- dorsal horn modulation
- suprasegmental modulation
What is allodynia
When an innocuous stimulus can be perceived as painful
What is hyperalgesia
The pain evoked by a noxious stimulus is exaggerated in both amplitude and duration
List the 4 types of pain
- Nociceptive pain= response to tissue injury
- Somatic pain= pain experienced in skin, muscle, bones and joints
- Visceral pain= organ pain (abdominal or thoracic)
- Neuropathic pain= Neuronal damage resulting on pain
Which 2 areas of the brain process pain ? Which aspects do they process?
Cortex= location of pain
Limbic brain= emotional response
What 4 parts of the brain do the ascending pain pathways connect to ? What do each of them do?
Cortex= localisation
Limbic brain= emotional response
Subcortex= cardiovascular, respiratory and behavioral changes
Hypothalamus = fight or flight response
What is somatotropy
Localisation of pain source
How can brain stem impact nociceptive pain
enhances pain signal from spinal cord using pronociceptive components. Can also feedback on impulse and reduce pain with antinociceptive components
What do descending controls act as
the body’s own analgesic
What do ascending pathways connect to, to create an unconscious response
Subcortical regions
What are nociceptors
Sensory receptors stimulated by damaging or potentially damaging stimuli (mechanical, chemical or thermal)
Describe polymodal receptors
sensitive to more than one stimulus modality
What are the possible stimuli to nociceptors
Thermal
Chemical
Mechanical
What is the difference between pain and nociception
Pain= the conscious understanding that something is hurting us Nociception = pathways generating the pain response, physiological process that results in perception but for us to "feel" pain we need to be conscious
What neurotransmitter regulates pain
Seretonin
What are the three main properties of pain receptors (nociceptors)
Some are polymodal (can be activated by multiple stimuli) some are not
Non- encapsulated nerve endings (peripheral end of sensory neuron)
Two types A (beta/alpha or delta ) or Cfibres
