Nociception and Pain Flashcards
(39 cards)
what are the classic 5 senses?
vision, hearing, touch, taste and smell
what other senses are there?
proprioception, itch, temperature, balance, visceral sensations, magnetosensation, electrosensation, pain
what is pain?
an unpleasant sensory and emotional experiences associated with actual or potential tissue damage
how is pain an evolutionary function?
- promotes survival
- want to avoid the stimuli
- requires aversion or treatment
what can happen if individuals have pain insensitivity?
- severe injuries
- leads to permanent tissue damage
what is nociception?
emotional component to pain
- pain is subjective
how is nociception different to other senses?
has both affective and emotional component
- nociception is not the same as pain
what are the 3 general nociception stimuli?
- chemical
- mechanical
- thermal
what is nociception detected by?
- nociceptors
give an overview of nociceotirs.
- dendritic free nerve endings of primary sensory neurons
- nociceptors fire action potentials in response to nociceptive stimuli
- located in tissues (different senses)
where do nociceptors send projections?
- send projection to the dorsal horn in the spinal cord
- make connections in the grey matter
where are the cell bodies located?
- mainly in the dorsal root ganglia (DRG)
- can be connections with motor neurons
what are the nociceptive fibres?
- thermal (activated by extreme temperatures)
- mechanical (activated by intense pressure to the skin)
- polymodal (activated by high intensity mechanical, chemical or thermal)
what are A fibres affected by?
mechanical and thermal
what is the structure of A delta fibres?
- small diameter
- 5-30m/s
- thinly myelinated
- slow
what are C fibres affected by?
polymodal
what is the structure of C fibres?
- small diameter
- unmyelinated
- <1m/s (very slow)
what do C and A delta fibres give rise to?
- first and second pain
- 3 classes of receptors are widely distributed and co-activated
- sharp pain = first pain (A delta)
- burning/ache = second pain (C fibres)
where are A delta and C fibres found?
the whole of the skin
apart from the webs between your fingers and the testicles
what are TRP channels?
transient receptor potential channels
what is the structure of TRP channels?
- 6 transmembrane protein with a gate
- variation in N and C termini defines physiological properties, attach to different proteins etc
- structural similarities but different TRPs mediate different functions
what is the function of TRP channels?
- in response to a stimulus it gates and allows Ca2+/Na+ through at different rations (causes a depolarisation)
what are the different stimuli of TRPs?
- conformational change (temp, mechanical, pH)
- ligand binding (endogenous and exogenous ligands)
- intracellular (Ca2+)
- an individual channel can be activated by >1 stimulus type
what is the structure of TRPV1?
- 6 transmembrane domains
- 3 anchor binding motifs (to cytoskeleton)
- phosphorylated by both protein kinase A and B
