Lecture 3: Somatosensory System II: Nociception, Temperature, Crude Touch

Question 1

free nerve endings can function as what receptors

Answer 1

chemoreceptors
thermoreceptors
mechanoreceptors
nociceptors

Question 2

what fibers do free nerve endings communicate with

Answer 2

c-fibers
a-delta

Question 3

why is it possible to get a papercut that is painful, but does not bleed

Answer 3

free nerve endings are located in the epidermis and blood vessels are located in the dermis

papercuts can involve only epidermis

Question 4

list the functions of cutanous free nerve endings

Answer 4

crude/non-discriminative touch
itch
temperature
noxious stimuli/pain
taste/smell

Question 5

where are free nerve endings highly concentrated in the body

Answer 5

lips and fingertips

Question 6

how is duration of a stimuli altered/affected

Answer 6

when stimuli stops, APs stop, duration stops

Question 7

how does frequency of action potentials affect the intensity of the stimuli

Answer 7

higher frequency of APs = increased intensity of stimuli

lower frequency of APs = decreased intensity of stimuli

Question 8

what temperature ranges would cause pain rather than hot/cld sensation

Answer 8

below 17 C and above 45 C

Question 9

what cranial nerve detects taste via hot/cold thermoreceptors

Answer 9

cn v

Question 10

what is defined by over-reaction of apin to the noxious stimuli

Answer 10

hyperalgesia

Question 11

how does the resting membrane potential determine one’s sensitivity to pain

Answer 11

higher resting membrane potential requires less depolarization needed for an action potential which allows for pain signaling to occur with low stimulus

Question 12

where are silent nociceptors most commonly located

how are they involved in hyperalgesia

Answer 12

joint capsule and visceral organs

increased receptor expression and localization to the endings

Question 13

describe the function of the axonal reflex

Answer 13

injury occurs at the axonal terminal branches which is sent back to the CNS as a pain signal (afferent)

axonal reflex sends out signal around the injured axonal terminal as a response for pain (efferent)

Question 14

describe the efferent functions of the axonal terminal

Answer 14

axonal reflex that signals blood vessels to leak which causes pain and swelling

Question 15

describe the afferent functions of the axonal terminal

Answer 15

injured axonal terminal sends pain signal along the central process to the spinal cord

Question 16

what fibers are involved with muscle pain

Answer 16

A-delta and C-fibers

Question 17

what is the function of the A-delta for muscle pain

Answer 17

stretch or contraction after exertion

Question 18

what would cause signalling along C-fibers in reguards to muscle pain

Answer 18

ischemia or after injury

Question 19

what fibers are involved in joint pain

Answer 19

A-delta and C-fibers

Question 20

what stimuli could lead to visceral pain

Answer 20

mechanical stimuli
ischemia
endogenous compounds

Question 21

t/f
viscera pain is diffused and always has a referral pattern

Answer 21

true

Question 22

what is a dermatome

Answer 22

segmental distribution of spinal nerve

Question 23

what is radiculopathy

Answer 23

compromised axons in a spinal nerve causing pain in a dermatome distribution

Question 24

what stimuli could be used to test for spinal nerve injury, specifically A-delta

Answer 24

pinprick
crude touch
temperature

Question 25

what fibers are described as largest axons and highly myelinated

Answer 25

alpha motor and 1a/1b sensory fibers

Question 26

what fibers are described as medium axons that are highly myelinated

Answer 26

gama motor neuron and II/A-beta sensory fibers

Question 27

what fibers are described as small axons and poorly myelinated

Answer 27

B visceral motor and A-delta sensory fibers

Question 28

what fibers are described as the unmyelinated, smallest axons

Answer 28

C-fibers

Question 29

what is the first order neuron for the anterolateral pathway

Answer 29

dorsal root ganglion

Question 30

what tract is utilized by the anterolateral system to ascend/descend information

Answer 30

lissauer's tract

Question 31

t/f C fiber 1st order neurons can project into the ventral root of a spinal nerve

Answer 31

true c fiber can pass through the ventral side of the spinal cord

Question 32

in the anterolateral system, (innocuous/noxious) input is more lateral in the dorsal root column

Answer 32

innocuous

Question 33

what lamina does A-delta project to what neurotransmitter is released

Answer 33

i, iii, iv, v glutamate

Question 34

what lamina do C-fibers project to what neurotransmitter is released

Answer 34

i, ii, iii, iv, v substance P

Question 35

A-delta is responsible for what sensory inputs what pathway does A-delta use to convey the stimuli

Answer 35

localized sharp pain, temperature, crude touch neospinothalamic pathway/lateral spinothalamic tract

Question 36

list the pathway that A-delta travels to relay information from the PNS to the CNS

Answer 36

info brought in via a-delta fiber synapse at the dorsal root ganglion synapse in specific lamina of the dorsal column crosses in the cord via anterior white commissure ascends to ventral posterolateral nucleus of thalamus (3rd order neuron) to postcentral gyrus/S1

Question 37

what sensory information are C-fibers responsible for

Answer 37

diffuse pain

Question 38

c-fibers use what tract in the anterolateral system

Answer 38

spinoreticular tract bilateral projection

Question 39

what pathways are used by c-fibers to relay information

Answer 39

paleospinothalamic and archispinothalamic

Question 40

paleospinothalamic pathway mainly relays (somatic/visceral) sensory information

Answer 40

somatic

Question 41

archispinothalamic pathway relays mainly (somatic/visceral) information

Answer 41

visceral

Question 42

the paleospinothalamic and archispinothalamic pathways relay information to ___ which includes ___

Answer 42

the reticular formation made up of: intralaminar nucleus and centromedian nucleus of thalamus

Question 43

after c-fiber information is passed to the reticular formation, where does the information get transferred to

Answer 43

insula/anterior cingulate gyrus, frontal lobe, limbic system for emotional overlapping

Question 44

at the medulla, lissauer's tract transforms into __

Answer 44

spinal trigeminal tract

Question 45

laminae II-IV transfrom into ___ at the medulla

Answer 45

spinal trigeminal nuclei

Question 46

the posterior spinal cord becomes ____ at the medulla

Answer 46

tegmental region of the medulla

Question 47

what is the 1st order neuron for CN V

Answer 47

trigeminal ganglion

Question 48

what is the 1st order neuron of CN VII

Answer 48

geniculate ganglion

Question 49

what is the 1st order neuron of CN IX

Answer 49

superior ganglion

Question 50

what is the 1st odrer neuron for CN X

Answer 50

superior ganglion

Question 51

what forms the the spinal trigeminal tract

Answer 51

central processes

Question 52

what is the 2nd order neuron of the spinal trigeminal pathway where are they located

Answer 52

spinal trigeminal nuclei caudal pons to C2 spinal level