physiology of pain Flashcards
definition of pain
a conscious experience arising from integrated activity in multiple sensory and emotional centres in the brain
definition of nociception
the physiological process involving transduction, transmission, and modulation of neural signals from periphery to CNS
what type of neurons are sensory nerves
pseudounipolar neurons
what are nociceptors
unmyelinated small diameter nerve endings in skin that sense actual or potential skin damage
where do the primary afferent sensory nociceptors have their cell bodies
dorsal root ganglion and enter the dorsal horn - terminate with C and Aδ fibres
where do ascending pathways travel
along nerve axons to the thalamus in the brain then to the somatosensory cortex
what do descending pathways control
impulse transmission in the dorsal horn and inhibit the pain
what is the route for pain
trigeminal pathway
associated with impulse activity in C and Aδ primary afferent fibres of the peripheral nerves
what do Aδ fibres convey
a sharp sensation of localised pain - fast pain
what do C fibres convey
a dull, diffusive, burning pain - slow pain
what is glutamate released by
nociceptive afferent neurons
what does glutamate do
acts on AMPA receptors and is responsible for fast synaptic transmission at the first synapse in the dorsal horn
what is the role of calcium ions and secondary messengers
induce central sensitisation in the dorsal horn and increase the efficiency of nociceptive transmission after injury
what is the gate control theory
rubbing the site of a painful stimulus helps alleviate the pain
occurs at spinal cord level
concurrent activity in large-diameter AB primary afferents reducing the transmission of pain signals in small diameter C afferents
what is nociception
detection of any noxious stimuli and translating it into neuro messages
