sensory systems Flashcards
where does the DRG lie and what are its targets?
it lies on the spinal nerve
its targets are skin and skeletal muscle.
what part of the SC is the brachial plexus and what does it do?
it’s between C3-T2.
it supplies the arm.
what part of the SC is the lumbosacral plexus and what does it do?
L3-S4
it supplies the leg.
what are the 3 subclasses of DRG neurons?
- proprioceptive neurons.
- low threshold mechanoreceptors.
- nociceptive neurons
what are proprioceptive neurons like?
- large diameter soma.
- myelinated neurons.
- terminate centrally in intermediate zone of ventral horn.
what info do proprioceptive neurons provide us with?
info on spatial awareness of limbs.
what are low threshold mechanoreceptors like?
- medium to large diameter soma
- moderately myelinated axons.
- terminate centrally in deep dorsal horn and project rostrally in dorsal columns.
what do proprioceptive neurons innervate?
muscle spindles and golgi tendons.
who do low threshold mechanoreceptors innervate?
sensory structures in skin.
what do Low threshold mechanoreceptors detect?
light touch, vibration, surface texture.
what are nociceptive neurons like?
- have a small soma.
- non-myelinated.
- terminate centrally in the superficial dorsal horn.
what do nociceptive neurons detect?
painful stimuli, temp, itch
Ascending fibre tracts carrying nociceptive info are found in what region of the SC?
the anterolateral region.
the spinothalamic tract is a … neuron relay?
3
spinothalamic tract has what neurons?
DRG - sensory
Spinoreticular tract detects what?
Dull, persistent, poorly localised pain and arousal response to nociceptive input.
Spinomesencephalic tract provides what?
an autonomic and emotional response to painful stimuli.
pain sensation is a … mechanism to minimise …
Pain sensation is a protective mechanism to minimise tissue damage.
what is hyperalgesia?
increased sensitivity of nociceptive neurons to pain stimuli
what does hyperalgesia cause?
guarding of damaged area and improved likelihood of healing.
what happens in a reflex response to painful stimuli?
- nociceptors detect painful stimuli.
- nociceptor sends action p to dorsal horn.
- nociceptor terminal in DH synapses with dendrites of an excitatory interneuron whose some in in DH.
- axon of interneuron projects to motor neurons in VH.
- motor neurons innervate muscles.
what are endogenous opioids?
small peptides that are produced by the body in response to physical exertion, pain, excitement and sexual pleasure.
