Lecture 4- peripheral pain Travers

Question 1

Which types of fiber makes up the majority of cutaneous nociceptors?

Answer 1

C fibers (87%)

A delta are the 13%

Question 2

Are C fibers myelinated?

Answer 2

no

Question 3

Are A delta fibers myelinated?

Answer 3

yes lightly

Question 4

Which fibers are responsible for “first pain” which is sharp and well-localized

Answer 4

a delta

Question 5

Which fibers are responsible for dull, burning, and lasting pain?

Answer 5

c fibers

Question 6

What kind of channels do a delta fibers have

Answer 6

Na channels: TTX sensitive

Question 7

What kind of channels do C fibers have

Answer 7

Na channels: TTX sensitive and TTX resistant

Question 8

branches of trigeminal with prominent chemethesis

Answer 8

1. ethmoid from V1
2. posterior palatine from V2
3. Nasopalatine from V2
4. Lingual from V3

Question 9

capsaicin can exhibit

Answer 9

desensitization

Question 10

dentinal tubules are innervated by… and they contain… and are important in… and… sensitivity

Answer 10

A delta fibers

• calcitonin gene related peptide
• mechanical and thermal

Question 11

pulp chamber is innervated by … fibers, conatin…. and exhibit ….. sensitivity and chemosensitivty to ….

Answer 11

C
substance P
thermal

Question 12

pulpal C fibers respond to inflammatory mediator….

Answer 12

bradykinin

Question 13

NH4CL and NaCl produce more of a …. pain andhistamine and bradykinin produce more of a …. pain

Answer 13

sharp

dull burning

Question 14

3 characteristics of hyperalgesia

Answer 14

prolonged spontaneous and response to non painful stimuli

Question 15

hyperalgesia- thermal or mechanical injury: C fiber responds and releases…. and then SP stimulates…. which release… and stimulate…

CGRP causes…. which is a …. to C fiber

Answer 15

• neuropeptides substance P or CGRP
• mast cells
• histamine
• C fiber
• vasodilation and swelling
• mechanical stimulus

Question 16

Hyperalgesia: damage that causes bleeding, same as thermal and mechanical AND ….. –>…. formation which stimulates …. and … products from…. which stimulates….

Answer 16

bradykinin
clot 
C fiber
platelet
5HT (serotonin)
C fiber

Question 17

Hyperalgesia: damage leading to infection and immune response can cause sensitization, ….. sensitize C fiber rather than causing direct excitation. …. also sensitize C fibers and protons released in inflamed tissue stimulate …. receptors and produce sensitization

Answer 17

• prostaglandins
• cytokines
• vanilloid/TRPV1

Question 18

A fibers Na channels are…. sensitive (… threshold) and K channels are….. (… conductance)

Answer 18

TTX, low threshold

BK, big conductance

Question 19

C fibers Na channels are…. resistant (…threshold) and K channels are….. (… conductance)

Answer 19

TTX, high threshold

BK and SK, small conductance

Question 20

prostaglandins block…. channel

Answer 20

SK

Question 21

Sensitization of vanilloid receptor (TRPV1): inflammation leads to lower threshold by:

1. presence of ….
2. …. of VR1 receptor
3. … in receptor #

Receptor is now activated at 22C instead of 42C

Answer 21

• inflammatory mediators (bradykinin/protons)
• Calcium activated phosphorylation
• increase