martin chapter 5

Question 1

pain, temperature and itch are mediated by which system?

Answer 1

anterolateral system

Question 2

where is the anterolateral system first relay?

Answer 2

in the dorsal horn of the spinal cord

Question 3

what are nociceptors?

Answer 3

sensory receptor neurons that are sensitive to noxious or tissue damaging stimuli and mediate pain. they respond to chemicals released from traumatized tissue

Question 4

3 classes of nociceptors

Answer 4

1. thermal
2. mechanical
3. polymodal

Question 5

pruriceptors

Answer 5

-respond to histamine
-subclass of nociceptors because sensitive to noxious stimulation as well

Question 6

name of receptor neurons sensitive to cold or warm

Answer 6

thermoreceptors
they detect changes in temperature within a normal physiological range

Question 7

among the different membrane receptors that nociceptors have, for the transduction of noxious stimuli into depolarizing sensory potential we have a specific family of receptors that is very important:

Answer 7

TRP->Transient receptor potential receptors

Question 8

type of axons of nociceptors, thermoreceptors and pruriceptors

Answer 8

small diameter axons
they can be both thinly myelinated (A-delta fibers) or non myelinated (C fibers)

Question 9

nociceptors with A delta fibers mediate?

Answer 9

fast pain (initial sharp, prickling pain)

Question 10

nociceptors with C fibers mediate?

Answer 10

slow pain (dull, burning, persistent)

Question 11

fiber types of pruriceptors?

Answer 11

pruriceptors are C fibers only

Question 12

hyperalgesia

Answer 12

exaggerated response to a noxious stimulus

Question 13

allodynia

Answer 13

feeling pain to a stimulus that normally doesn’t produce pain

Question 14

where do small diameter fibers (that subserve pain, temperature and itch) enter in the spinal cord?

Answer 14

in the lissauer tract. the white matter region that caps the dorsal horn
NB: this tract is lightly stained despite being white matter because the fibers are either thinly myelinated or non myelinated

Question 15

what do neuron clusters in the spinal cord form?

Answer 15

rexed laminae
we have 10 rexed laminae

Question 16

which laminae comprise the dorsal horn?

Answer 16

from lamina I to VI

Question 17

which laminae comprise the ventral horn?

Answer 17

laminae VIII and IX

Question 18

which laminae comprise the intermediate zone?

Answer 18

laminae VII and X

Question 19

which lamina comprise the grey matter surrounding the central canal?

Answer 19

lamina X

Question 20

decussation in the anterolateral system happens in?

Answer 20

the ventral (anterior) commissure, ventral to the central canal

Question 21

Where are axons transmitting info from caudal segments located in the anterolateral system ( in respect to axons transmitting info from more rostral segments) ?

Answer 21

axons transmitting info from caudal segments are located lateral to axons transmitting info from more rostral segments

Question 22

what is a spinal hemisection?

Answer 22

damage to one half of the spinal cord

Question 23

why is the sensory loss contralateral to the side of the lesion in the anterolateral system?

Answer 23

because the axons of the anterolateral system decussate in the spinal cord

Question 24

what is the reticular formation?

Answer 24

a heterogeneous collection of nuclei serving many somatic sensory, visceral, motor and regulatory function

Question 25

where do the mechanosensory, the pain, the temperature and the itch projections terminate?

Answer 25

in the ventral posterior lateral nucleus. their terminal fields hardly overlap.the mechanosensory projections tend to be located rostral to the projections of pain, temperature and itch

Question 26

where do the ventral medial posterior nucleus project?

Answer 26

in the insular cortex, which is important for perception of the quality and intensity of pain, temperature and itch and in mediating behavioral and autonomic responses

Question 27

where do the medial dorsal nucleus project?

Answer 27

into the anterior cingulate gyrus, involved in the emotional aspects of somatic sensory stimulation

Question 28

for acute pain there is the activation of multiple areas of the cerebral cortex termed "the pain matrix". name these areas

Answer 28

-primary and secondary somatic sensory areas -anterior cingulate cortex -prefrontal cortex -insular cortex -some areas of the thalamus and the amygdala

Question 29

among the cortical areas, which one is most consistently activated during painful stimuli?

Answer 29

the insular cortex