Pain Flashcards
What is pain?
An unpleasant sensory and emotional experience associated with potential tissue damage.
What is acute pain?
Pain lasting less than 12 weeks
What is chronic pain?
Pain lasting more than 12 weeks
What is nociceptive pain?
Pain that arises from actual damage to non-neuronal tissue.
What is neuropathic pain?
Pain that arises from a primary lesion of the nervous system
What is the name given to sensory neurones that can sense both external and internal pain?
Nociceptor
What is released when tissue is damaged to make nociceptors more sensitive to stimuli?
Bradykinin & Prostaglandin E2
Name the two types of afferent nociceptor fibres.
Alpha delta fibre
C-fibre
Give the characteristics of alpha delta fibres.
Thinly myelinated
Medium conduction speed
Carry touch, pressure, temperature, FAST pain information
Give the characteristics of C-fibres.
Unmyelinated
Slow conduction speed
Carry temperature, touch, pressure, SLOW information
Which neurotransmitter do alpha delta fibres release?
Glutamate
Which neurotransmitter do C-fibres release?
Glutamate & Substance P
Which part of the brain does all sensation (bar Olfactory) pass through?
Thalamus
Which part of the brain is responsible for judging the degree of pain?
Insula. Lies within sylvian fissure.
Which part of the brain is involved with the emotional response to pain?
Cingulate gyrus. Located on medial aspect of cerebral hemispheres.
Where is the periaqueductal grey located?
Midbrain.
Briefly describe how the periaqueductal grey descending pain pathway is activated during extreme stress.
Opoid receptors are activated > Reduction in pre-synaptic neuronal sensitivity, reduction in Substance P release > Reduced pain sensation > Analgesia
Define analgesia
The selective suppression of pain without effects on consciousness
Define anaesthesia
The uniform suppression of pain. Consciousness can be lost.
Which drugs bind to opioid receptors?
Morphine, methadone, codeine
What is the Melzack-Wall pain gate?
A theory that states that non-painful input closes the ‘gate’ to painful input, preventing pain sensation from travelling to the somatosensory cortex to be perceived.
How do local anaesthetics work?
Block sodium channels, preventing neurones from depolarising so no action potential is developed. Results in pain relief as pain is not transmitted.
