Lecture 4- peripheral pain Travers Flashcards
Which types of fiber makes up the majority of cutaneous nociceptors?
C fibers (87%)
A delta are the 13%
Are C fibers myelinated?
no
Are A delta fibers myelinated?
yes lightly
Which fibers are responsible for “first pain” which is sharp and well-localized
a delta
Which fibers are responsible for dull, burning, and lasting pain?
c fibers
What kind of channels do a delta fibers have
Na channels: TTX sensitive
What kind of channels do C fibers have
Na channels: TTX sensitive and TTX resistant
branches of trigeminal with prominent chemethesis
- ethmoid from V1
- posterior palatine from V2
- Nasopalatine from V2
- Lingual from V3
capsaicin can exhibit
desensitization
dentinal tubules are innervated by… and they contain… and are important in… and… sensitivity
A delta fibers
- calcitonin gene related peptide
- mechanical and thermal
pulp chamber is innervated by … fibers, conatin…. and exhibit ….. sensitivity and chemosensitivty to ….
C
substance P
thermal
pulpal C fibers respond to inflammatory mediator….
bradykinin
NH4CL and NaCl produce more of a …. pain andhistamine and bradykinin produce more of a …. pain
sharp
dull burning
3 characteristics of hyperalgesia
prolonged spontaneous and response to non painful stimuli
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
- neuropeptides substance P or CGRP
- mast cells
- histamine
- C fiber
- vasodilation and swelling
- mechanical stimulus
Hyperalgesia: damage that causes bleeding, same as thermal and mechanical AND ….. –>…. formation which stimulates …. and … products from…. which stimulates….
bradykinin clot C fiber platelet 5HT (serotonin) C fiber
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
- prostaglandins
- cytokines
- vanilloid/TRPV1
A fibers Na channels are…. sensitive (… threshold) and K channels are….. (… conductance)
TTX, low threshold
BK, big conductance
C fibers Na channels are…. resistant (…threshold) and K channels are….. (… conductance)
TTX, high threshold
BK and SK, small conductance
prostaglandins block…. channel
SK
Sensitization of vanilloid receptor (TRPV1): inflammation leads to lower threshold by:
- presence of ….
- …. of VR1 receptor
- … in receptor #
Receptor is now activated at 22C instead of 42C
- inflammatory mediators (bradykinin/protons)
- Calcium activated phosphorylation
- increase
