L7- Sensory Systems Flashcards
Need for sensory systems
Maintain homeostasis, detect/ react to changes in environment, protect body from noxious stimuli
What is sensory homunculus
A map representation of the sensory system
Touch
Touch receptors: mechanoreceptors (pressure), thermoreceptors (temp), nociceptors (noxious stimuli (pain))
Nociceptors and location
Termoreceptor- A delta
Merchanoreceptor- A delta
Polymodal - C
How are polymodal nociceptors activated
High intensity mechanical, chemical and thermal stimuli
neuronal pathway always involved in pain transmission
Primary afferent neurons.
- a special class of neurons which have their cell bodies in the dorsal root ganglia
Speed of C/A delta fibres in primary afferent neurons
Relatively slow
Type of pain A delta fibres mediate
Sharp fast pain
What fibres are myelinated
A delta
Second pain mediated by what
Relatively slow C fibres which mediate a longer lasting second pain
Type of fibres which are unmyelinated
C fibres
Nociceptive pain activates
A delta and C fibres
What acts as a gate in gate theory of pain
Substantia gelitanosa
What does paracetamol inhibit
Cox3
How do local anaesthetics work
Intracellular block of sodium channels
unionised LA enters cell which becomes ionised intracellularly. This blocks sodium channels so pain signalling is inhibited
Opioids can block ____
Perception, modulation and transmission pathways
