What is pain?
Unpleasant sensory / emotional experience
Associated with tissue damage or described in terms of it
Does pain mean that tissue damage is occurring?
Which type of pain is a short-term response to prevent tissue damage?
What is the purpose of inflammatory pain?
Stops you from touching a damaged area until healing has occurred
How long does inflammatory pain persist for?
Days - Weeks
What are some adjuvant drugs which can be used to control pain?
Describe pain originating from the skin.
stabbing, pricking, burning
Pain originating from the muscle and viscera tend to be ___ localised.
Visceral pain tends to be ___.
Muscle pain tends to be ___.
Pain can be ___ to distant areas.
Which receptors detect intense stimuli to cause the sensation of pain?
What sort of stimulus triggers a nociceptor?
High intensity stimuli
of a THERMAL, MECHANICAL or CHEMICAL nature
Nociceptors are which order neurons?
FIrst order neurons
What are the factors influencing the conduction velocity of a neuron?
2. Diameter of axon
Which type of sensory fibre transmits fast pain?
look back at the table of conduction velocities
Which type of sensory fibre transmits slow pain?
look back at table of conduction velocities
a) fast pain
b) slow pain
a) Stabbing, pricking, burning
b) Aching, throbbing
Which ions enter a neuron to cause a depolarisation?
Why does injured tissue feel hot?
One of the TRP channels responsible for noxious heat is activated
What does polymodal mean in terms of nociceptors?
Respond to more than one noxious stimulus
At which specific temperature does warmth become unpleasant heat?
43 degrees Celsius
Which two types of nerve fibre make up most nociceptors?
A-delta ('fast' pain fibre)
C ('slow' pain fibre)
Which neurotransmitters are involved in the transmission of pain signals?
The more a synapse is activated, the more ___ it becomes.
What is released at the peripheral terminal of a nociceptor when it is activated?
What causes sterile neurogenic inflammation?
Release of inflammatory mediators from the PERIPHERAL terminal of activated nociceptors
Which neurotransmitter is released into the synaptic cleft when a pre-synaptic sensory fibre is activated?
Which change in membrane potential does it cause?
Depolarisation (excitatory post-synaptic potential)
Two ligands, AMPA and NMDA, bind to receptors to change the type of excitatory post-synaptic potential that is produced.
What does each cause?
AMPA - fast
NMDA - slow
The excitatory post-synaptic potential causes a depolarisation which overcomes threshold potential.
What happens next?
What does repeated stimulation of a synapse cause in the long term?
giving rise to hyperalgesia and allodynia