Pain Signals
● Can be perceived pain, even without real tissue damage
Pain Process
● Transduction
○ How nociceptors send pain signals
○ When pain happens
○ Releases chemical mediators to activate sensory neurons and nociceptors
■ Chemical mediators are local and thus released immediately upon tissue
damage
● Transmission
○ Release of APs
■ Aβ: large and myelinated (fast)
■ Aδ: small and myelinated (fastest)
■ C: small and unmyelinated (slow)
○ Converge in dorsal root ganglion
● Perception
○ The feeling of “pain”
○ Thalamus as relay station
■ Source of damage → thalamus → CNS
● Modulation
○ If pain gets better or worse
○ Cortex and synapses in mid- and hindbrain
○ Influences nociceptors in spinal cord
■ Activation = more pain
○ Pain diminishes over time by inactivation of nociceptors
■ Or via pharmacological remedies
Neuropathy
● Unlike nociception, not chemical/mechanical stress
● Prolonged CNS damage
○ Infection, diabetes, herpes, previous trauma
● Affects how pain-relieving drugs work
● “Harmful pain”
○ Whereas nociception alerts body of a threat
● Chronic
● Often not localized
Pediatric Medication
● Fentanyl: 0.5-1µg/kg (max 50µg)
○ Typically best option
● Morphine: 0.05-0.1mg/kg (max 5mg)
● Ketamine 0.1-0.3mg/kg (max 30mg)
● Can be perceived pain, even without real tissue damage
Pain Process
● Transduction
○ How nociceptors send pain signals
○ When pain happens
○ Releases chemical mediators to activate sensory neurons and nociceptors
■ Chemical mediators are local and thus released immediately upon tissue
damage
● Transmission
○ Release of APs
■ Aβ: large and myelinated (fast)
■ Aδ: small and myelinated (fastest)
■ C: small and unmyelinated (slow)
○ Converge in dorsal root ganglion
● Perception
○ The feeling of “pain”
○ Thalamus as relay station
■ Source of damage → thalamus → CNS
● Modulation
○ If pain gets better or worse
○ Cortex and synapses in mid- and hindbrain
○ Influences nociceptors in spinal cord
■ Activation = more pain
○ Pain diminishes over time by inactivation of nociceptors
■ Or via pharmacological remedies
Neuropathy
● Unlike nociception, not chemical/mechanical stress
● Prolonged CNS damage
○ Infection, diabetes, herpes, previous trauma
● Affects how pain-relieving drugs work
● “Harmful pain”
○ Whereas nociception alerts body of a threat
● Chronic
● Often not localized
Pediatric Medication
● Fentanyl: 0.5-1µg/kg (max 50µg)
○ Typically best option
● Morphine: 0.05-0.1mg/kg (max 5mg)
● Ketamine 0.1-0.3mg/kg (max 30mg)
