Flashcards in Somatosensory and Pain - Kenyon Deck (145)
What is the general function of primary afferent neurons?
Encode mechanical, chemical, or thermal stimulus into a receptor or generator potential
Are generator and action potentials the same
Describe a generator potential?
small, graded, and NOT CONDUCTED.
Generator potential is equivalent to what type of post-synaptic event?
Where are the cell bodies of PANs?
in the DRG
Are there synapses in the DRG?
Normally speaking, NO
Are there IPSPs or EPSPs in the DRG?
No, all electrical activity passes right through it
"A" fibers have a (large/small) diameter and conduct (fast/slow)
C fibers are (large/small) diameter and conduct (fast/slow)
C and A-delta conduct what signals?
Pain and temperature
which fiber type is the fastest and what type of signal does it carry?
what are the slowest fibers?
C and A-delta
Does the fast/slow differentiation have any impact on actual ability to conduct?
Do specialized receptors of PAN's adapt to stimuli?
Some adapt quickly, some slowly, some not at all. Theyre the goldilocks bears of neuroscience.
In two-pt. discrimination, what happens as you move the points farther apart?
AP frequency from the central receptive field lowers while frequency increases in the lateral receptive fields
Describe the pathway taken for TVP and Pain and Temp from the body and back of head?
PAN's to DRG to dorsal roots to dorsal column to medial lemniscus
Describe the path for TVP, pain, and temp, form the the face and teeth?
PAN's to trigeminal ganglion
When axons enter the spinal cord, what types of events utilize the pathway that synapse in Rexed Layer 3 of the cord?
spinal reflexes: knee jerk, somato-somatic, viscero-somatic
When axons enter the spinal cord and branch without synapsing, what do these form?
The dorsal columns of he spinal cord
Lower limbs form what tract?
medial gracile tract
Upper limbs, trunk and neck form what tract?
lateral cuneate tract
With respect to dorsal column somatotopy, what body structures will be more lateral? More medial?
lateral: occiput and neck
medial: lower limb and trunk
Will we see facial innervation in the the somatotopy of the dorsal column?
No, that stuff goes through the trigeminal!
What is the effect on TVP of lesions in the dorsal column? what does this tell us about TVP fibers?
There is PARTIAL loss of TVP; dorsal columns are NOT the only pathway for TVP
Axons from the dorsal columns synapse with second order neurons in which nuclei?
Is the information at the gracile and cuneate nuclei simply relayed or is it processed?
it is processed
The (blank) tract is the pathway in which axons go ventral and corss over to form the medial lemniscus
Internal Arcuate tract
Axons from the lower body end up (ventral/dorsal)
Fibers from the gracile or cuneate tracts synapse in the (blank or blank) nuclei
Gracile or cuneate nuclei