Pain Pathways (Exam II) Flashcards
Differentiate the sensory-discriminative & motivational-affective aspects of pain.
- Sensory-discriminative - Ascending pathways and the perception of pain (location, intensity, sensation, etc.)
- Motivational affective - responses to painful stimuli (Ex. arousal, reflexes, endocrine responses, and emotional changes)
What is nociception?
- The experience of pain through a series of complex neurophysiologic processes.
What are the four stages of pain perception?
- Transduction (tissue level)
- Transmission (via nerves)
- Modulation (via spinal cord)
- Perception (CNS)
The process by which a noxious stimulus (e.g., heat, cold, mechanical distortion) is converted to an electrical impulse in sensory nerve endings, is known as?
Where does it occur?
Transduction
Peripheral nociceptors
(slide 8)
____________ is the conduction of (pain-related) nerve/electrical impulses to the ___ with the major connections for these nerves being in the ______ horn of the spinal cord and ________ with projections to the cingulate, insular, and somatosensory cortices.
Transmission;
CNS;
Dorsal;
Thalamus
Define Modulation:
Where does it occur in the CNS?
Modulation of pain is the process of altering (inhibitory/excitatory) pain transmission mechanisms.
Occurs in the Dorsal Horn of the spinal cord
At what level on the pain perception pathway do our injectable local anesthetics (LA) become active at?
Will Modulation still occur once LA have been injected properly?
between the Transduction and Transmission levels
No: “Hence, there will be NO modulation because there would be no pain transmission to the dorsal horn…”
Where does the modulation of pain impulses occur?
- Dorsal horn of the spinal cord
What drugs are used to affect the transduction of pain?
What specifically is being affected by these drugs?
- Local anesthetics & NSAIDs
- Peripheral nociceptors
What drugs are used to affect the transmission of pain?
What specifically is being affected by these drugs?
- Local anesthetics
- Αδ and C fibers
What drugs are used to affect the modulation of pain?
What specifically is being affected by these drugs?
- LA’s, opioids, ketamine, α2 agonists
- Afferent fibers of the dorsal horn
What drugs are used to affect the perception of pain?
What specifically is being affected by these drugs?
- General anesthetics, opioids, α2 agonists
- Brain
Where are nociceptors located? (VVM SJ)
- Skin
- Muscles
- Joints
- Viscera
- Vasculature
What characterizes afferent C-fibers?
- Unmyelinated
- Pain from heat (burning) & sustained pressure
- Slow (less than 2 m/s)
What characterizes Aδ fibers?
-Myelinated
- Type I: Aβ & Aδ (heat,mechanical, chemical)
- Type II: Aδ (heat)
- Fast (>2 m/s)
What chemical mediators of pain are targeted with spinal anesthetics?
Peptides
- Substance P
- Calcitonin
- Bradykinin
Lipids
- Prostaglandins
- Thromboxanes
- Endocannabinoids
Which chemical mediator is released first in response to injury?
- Bradykinin
What chemical mediators of pain are inhibited by NSAIDs?
Lipids
- Prostaglandins
- Thromboxanes
What chemical mediators of pain are inhibited by cannabis?
Lipids
- Endocannabinoids
What is sensitization?
- The increased responsiveness of peripheral neurons responsible for pain transmission to heat, cold, mechanical or chemical stimulation
- AKA Decreased pain threshold (likely due to upregulation of receptors)
Differentiate hyperalgesia and allodynia.
- Hyperalgesia - ↑ pain sensations to normally painful stimuli.
- Allodynia - perception of pain to things that aren’t normally painful.
