Pain (19.2) Flashcards
What are the functions of pain?
Protects tissue
Detects, localizes, and identifies tissue damaging processes
Gives diagnostic clues (quality, time course, locations)
Define acute pain:
<1 week
Define chronic pain:
At least 6 months (considered an autonomous disease)
What is the chronic regional pain syndrome?
Limb is cold, red, muscle wasting and nail changes
What are opiates?
Derivatives of poppy plants (heroin and morphine)
What are opioids?
Any drug that occupies opioid receptors (fentanyl, methadone)
Which opioid receptor is important for pain?
Mu receptor
Where are Mu receptors found? (generally)
Spread through the CNS and gut and also found on WBCs
How do opioids work in the CNS?
Inhibit GABA and thus disinhibit dopamine
Where in the CNS are Mu receptors found?
Descending pain circuit: amygdala, mesencephalic reticular formation, PAG, rostral ventral medulla
Where in the PNS are Mu receptors found?
Primary afferent neurons, peipheral sensory nerve fibers, DRG
What are the two mechanisms of release for opioids?
Peripherally mediated by stress and ACTH co- release
Centrally mediated involves innervation of the hypothalamus, midbrain and rostral medulla
T/F: Opioids are co released with ACTH during stress reactions from the anterior pituitary
True
What are the releasing mediators for opioids?
5- HETE, LTA4, LTB4 and other lipoxygenase products
Angiotensin II
5- HT
With opioid treatment, what happens to the pressure needed to create pain when opioids are used?
Opioid induced hyperalgesia–> the amount of pressure needed to cause a pain response decreases as the time on opioid increases