Physiology of Pain Flashcards
What are the four different steps of pain?
Transduction, Translation, Perception, Modulation
What occurs during transduction?
Neurotransmitters are released, converts stimulus (mechanical, thermal, chemical) to electrical impulse
What occurs during translation?
Electrical impulse relayed to dorsal horn in CNS, processed by neurotransmitter, sent to thalamus, then relayed to the cerebral cortex.
What occurs during perception?
Pain is perceived in the cerebral cortex - “ouch!”
What is modulation?
This is different pathways that inhibit pain
What is a nociceptor and where are they located?
Nociceptor is a nerve receptor that transmits pain and they are located at the ends of small afferent neurons.
What are nociceptors stimulated by?
Direct cell damage (noxious stimulus), and neurotransmitters like substance P, histamine, bradykinin, and prostaglandins
What effect does substance P have?
Inflammatory
What effect does histamine have?
Itching
What effect does bradykinin have?
Vasodilator causing swelling, redness, tender
What effect do prostaglandins have?
↑ sensitivity of pain
Describe nociceptive pain.
- Described as aching or throbbing
* Responds to nonopioid and opioid analgesics
T or F: The bigger and more myelinated the afferent neurons are, the faster the transmission will occur.
TRUE
Characteristics of C fibers (nociceptors).
They are slow (2m/sec), dull, aching, burning pain, slow onset, longer duration
• Ex: wack thumb with hammer - after throbbing feeling
Characteristics of A-delta fibers (nociceptors).
They are quicker (15m/sec), sharp, localized pain, short duration
•Ex: step on knife …. THEN would be C fibers
Characteristics of A-beta fibers (non-nociceptors)
faster than C and A-delta fibers (70 m/sec), stimulate skin by touching
Characteristics of A-alpha fibers (non-nociceptors)
faster than c and A-delta fibers (120m/sec), stimulated by massaging muscles
What is the “Gate Theory of Pain” opened by?
nociceptor input, anxiety, worry, and concentration on pain
What is the “Gate Theory of Pain” closed by?
non-nociceptor input, positive mood, concentration on things other than pain
How does the endogenous analgesic system work?
- pain impulses activate descending nerve fibers, triggering release of neurotransmitters including endogenous opioids.
- these endogenous opioids bind to opiate receptors on nerve cells, inhibit substance P release, and decreases pain transmission to brain
what else triggers the release of endogenous opioids?
Pleasurable experiences, including meditation, alcohol, acupuncture, massage, music therapy, walking bare foot on grass
