Exam 2 - Pain pathways Flashcards
(53 cards)
What are the two components that are involved in the complex phenomenon of pain?
- Sensory - discriminative
- Motivational-affective
What is the sensory-discriminitive portion of pain?
- The perception of pain by the brain; ascending pathway
- spinothalamic/trigemino-thalamic tracts → somatosensory cortex
What is the motivational-affective portion of pain?
- The responses to painful stimuli
- Attention/arousal
- Somatic/autonomic reflexes
- Endocrine response
- Emotional response
Where does perception of motivational-affective pain occur?
Limbic cortex (emotional center) and thalamus
Term for increased pain sensations to normally painful stimuli
Hyperalgesia
Term for perception of pain sensations in response to normally non-painful stimuli
Allodynia
List the steps in the pain perception pathway
- Transduction - of pain via peripheral nociceptors
- Transmission - of pain via nerves
- Modulation - (inhibition/exitation) of pain at the dorsal root ganglion and dorsal horn
- Perception - of pain via ascending spinothalamic tract at the somatosensory cortex
This brain strutctire acts at the central relay station for incoming pain signals
Thalamus
Local anesthetics and NSAIDS alter what part of the pain pathway?
LA: transduction, transmission, and modulation
NSAIDs: transduction
Opioids, ⍺2-agoinsts, general anesthetics, and ketamine alter what parts of the pain pathway?
Opioids and ⍺2-agoinsts: Modulation and perception
Ketamine: modulation
General anesthetics: Perception
Unmyelinated C-fibers transmit what signals?
burning and pressure
Myelinated A-fibers type I and II transmit what signals?
Type I (Aβ and A𝜹): heat, mechanical, chemical
Type II (A𝜹): heat
What 4 peptides act as chemical mediators?
Substance P, calcitonin, bradykinin, CGRP
What is the first chemical mediator released?
Bradykinin
What are the lipid chemical mediators released in response to pain?
Prostaglandins, thromboxanes, leukotrienes, endocannabinoids
PELT
What are the other chemical mediators released during pain that are not lipids or peptides?
- Eicosanoids
- Neutorphins
- Cytokines
- Chemokines
- Proteases and protons
List the types of receptors and channels involved in the dorsal root ganglion and peripheral terminals?
- Purinergic
- Metabotropic
- Glutamatergic
- Tachykinin
- TRPV I
- Neurotrophic
- Ion channels
The increased responsiveness of peripheral neurons responsible for pain transmission to heat, cold, mechanical or chemical stimulation is called ____?
Sensitization
Describe primary hyperalgesia?
- Occurs at the original site of injury from heat/mechanical injury
- Causes decreased pain threshold, increased response, spontaneous pain, and expansion of the receptive field
What population has a decreasd pain threshold and exaggerated pain responses?
Neonates
Pain perception at 23 weeks
Describe secondary hyperalgesia?
Characterized by enhanced pain by mechanical stimuli in the uninjured skin
These laminae synapse with afferent C fibers?
Which one does opioids work on?
Lamina I (lamina marginalis)
Lamina II (substantia gelatinosa) - opioids work here
These laminae synapse with A-fibers from muscles and viscera?
Laminae I, IV, VIII and the ventral horn
What laminae contain the NKI receptor with substance P?
What do we do that affects these laminae?
- Laminae III and IV
- Spinal anesthesia