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VMED 5267 - Pain
Pathways
1. Features of acute pain?: • It is associated with tissue damage or the threat to some tissue injury
• Occurs when a stimulus activates high-threshold sensory nerve fibers
• Serves a protective role
• Alters animal's behavior to avoid or minimize damage to the tissue
• Associated with surgery, trauma, some medical conditions
• Disappears with healing (days, weeks)
• Tends to be self-limiting
• Physiologic
2. Features of chronic pain?: • Persists beyond the expected course of healing
• Usually associated with chronic inflammation, degenerative disease, or following nerve
injury or damage
• No biological purpose
• May be considered as a disease state
• Induces biochemical and phenotypical changes in the nervous system
• Peripheral and central sensitization
• Difficult to treat
• Pathologic or maladaptive
3. What transmits visceral pain (diffuse and poorly localized)?: fibers (A-5aÿnd C) that travel along
sympathetic and parasympathetic pathways
4. What occurs during transduction?: Activation/depolarization of nociceptors transforms the
mechanical/thermal/chemical information into an electrical impulse
• Nociceptors encode the intensity, duration, location, and quality of the stimuli
5. What are nociceptors?: • Represent the free-endings of primary sensory neu- rons (A-5aÿnd C-fibers)
• No spontaneous depolarization
• High-threshold ’ respond only to noxious stimuli
6. What are types of nociceptors?: Thermoreceptors
• Heat: transient receptor potential vanilloid-1 (TRPV-1)
• Cold: transient receptor potential menthol-8 (TRPM-8)
Mechanoreceptors
• Transient receptor potential A1 (TRPA-1), TRPV-1
Chemoreceptors
• Acid-sensing ion channels (ASICS), TRPA-1
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4
VMED 5267 - Pain
Pathways
1. Features of acute pain?: • It is associated with tissue damage or the threat to some tissue injury
• Occurs when a stimulus activates high-threshold sensory nerve fibers
• Serves a protective role
• Alters animal's behavior to avoid or minimize damage to the tissue
• Associated with surgery, trauma, some medical conditions
• Disappears with healing (days, weeks)
• Tends to be self-limiting
• Physiologic
2. Features of chronic pain?: • Persists beyond the expected course of healing
• Usually associated with chronic inflammation, degenerative disease, or following nerve
injury or damage
• No biological purpose
• May be considered as a disease state
• Induces biochemical and phenotypical changes in the nervous system
• Peripheral and central sensitization
• Difficult to treat
• Pathologic or maladaptive
3. What transmits visceral pain (diffuse and poorly localized)?: fibers (A-5aÿnd C) that travel along
sympathetic and parasympathetic pathways
4. What occurs during transduction?: Activation/depolarization of nociceptors transforms the
mechanical/thermal/chemical information into an electrical impulse
• Nociceptors encode the intensity, duration, location, and quality of the stimuli
5. What are nociceptors?: • Represent the free-endings of primary sensory neu- rons (A-5aÿnd C-fibers)
• No spontaneous depolarization
• High-threshold ’ respond only to noxious stimuli
6. What are types of nociceptors?: Thermoreceptors
• Heat: transient receptor potential vanilloid-1 (TRPV-1)
• Cold: transient receptor potential menthol-8 (TRPM-8)
Mechanoreceptors
• Transient receptor potential A1 (TRPA-1), TRPV-1
Chemoreceptors
• Acid-sensing ion channels (ASICS), TRPA-1
1/
4
