Opioids Flashcards
(56 cards)
What is the pathway of orofacial pain
Nociceptors on trigeminal nerve endings –> A-d fibers and C fiber –> Trigeminal ganglion –> Trigeminal nuclei on the brainstem –> Thalamus –> Limbic Systema and Cerebral cortex
T/F - Orofacial pain follows a path different than other pain pathways throughout the body
False - it’s the same
Where are nociceptors located?
Throughout the skin, oral mucosa, and tooth pulp
A-delta fibers
Faster, myelinated axons response first to noxious mechanical stimuli
Produce the initial sensation of sharp pain
C fibers
Slower, unmyelinated axons that respond to thermal, mechanical, and chemical assaults
Dull, aching, or burning pain
Are there more C or A-delta fibers in the body?
There are 5x more C fibers than A-delta
Nociceptor signaling
Nociceptors are molecular sensors
Different nociceptors respond to various noxious stimuli such as heat, cold, mechanical perburbations, or protons
Their activation leads to local depolarization which in turn initiates action potentials
How does inflammation cause pain?
Mediators such as prostaglandins, substance P, TNF-a, Il-16, and Il-6 interact with nociceptors and facilitate the transmission of pain signals
T/F - Tissue injury can lead to sensitization of the pain response
True
Where can pharmacologic intervention occur to diminish pain?
At the periphery
Periphery signaling to the CNS
CNS activity
Where do NSAIDs and SAIDs act to diminish pain?
Inhibition at the periphery
Where do local anesthetics act to diminish pain?
Inhibition of signaling to the CNS
Where do opioids act to diminish pain?
Inhibition at the periphery and
Inhibition of CNS activity
What are the four families of endogenous opioids?
Pro-opiomelanocortin peptides
Pro-enkephalin peptides
Prodynorphin peptides
Endomorphins
What are the three important opioids receptors?
Mu (u)
Kappa (k)
Delta (d)
Opioids receptors
GCPRs
Widely distributed in the CNS
They activate Gai
B-endorphin
31 amino acid peptide
Natural agonist of the u-opioid receptor
Where is B-endorphin made, and what is it made from?
Formed from processing of pro-opiomelanocortin (POMC)
Made in the pituitary and hypothalamus
Met-enkephalin
5 amino acid peptide (pentapeptide)
Derived from pro-enkephalin precursor
Found in the adrenal medulla and throughout the CNS
Natural agonist of the d receptor
Leu-enkephalin
5 amino acid peptide (pentapeptide)
Derived from pro-enkephalin and pro-dynorphin
Found throughout the CNS
Natural agonist of the d receptor
Dynorphin A
13 aa peptide
Derived from Pro-dynorphin precursor
Found throughout the CNS
Natural agonist of the k receptor
Dynorphin B
13 aa peptide
Derived from Pro-dynorphin precursor
Found throughout the CNS
Natural agonist of the k receptor
a/B neo-endorphin
10 aa peptide (a) 9 aa peptide (B) Derived from Pro-dynorphin precursor Found throughout the CNS Natural agonist of the k receptor
What do opioid receptors activate?
Gai and GBGy
