Pain pathways (FS Week 3) Flashcards
What receptor is pain detected by?
Nociceptors
What is a bipolar neuron? In relation pain pathways, where is the cell body and where do the projections travel to?
A bipolar neuron is a neuron with 2 projections off the cell body.
the cell body is in the dorsal horn
one axon projection to dorsal horn and one axon projection to the periphery
What do peripheral sensory nerves respond to
heat/cold
mechanical stimulation
chemical stimulation
Name 2 ion channels located in the nociceptors
TRP (Transient receptor channels) - activated by chemicals
P2X channels - excited by ATP
What is meant by hyperalgesia
Increased sensitivity to pain which is caused by noxious stimuli (stimuli that is supposed to cause pain e.g. surgery)
What is meant by allodynia
a type of pain- increased sensitivity to touch caused by non-noxious stimuli (stimuli that is not supposed to cause pain)
What are 4 types of afferent neurons
- nociceptors
- Ad-fibres
- C-fibres
- Ab- fibres
Give 3 features of Ad-fibres
- myelinated
- stimulated by temperature (cold) and mechanical stimuli
- associated with acute/sharp pain - fast
Give 3 features of Ab-fibres
- myelinated
- stimulated by touch and pressure
- low intensity transmission (normal touch signal)
Give 3 features of C-fibres
- unmyelinated
- slow/deep pain transmission
- stimulated by temperature (hot), chemical (inflammatory mediators) and mechanical stimuli
What is the gate-control theory
the gate is the spinal cord
the theory suggests that non-painful input closes the nerve gates to painful input which prevents painful sensation travelling to the thalamus
How is pain modulated
- gate control
- descending pathway
The main pain pathways travel from the periphery to the brain via which of the structures below?
spinothalamic tract
The main pain pathways travel from the periphery to the brain via which of the structures below?
spinothalamic tract
