bio week 11

• What are the types of afferent fibre groups related to pain?

  I, II, III, IV
• What is the fibre diameter range for group I afferent fibres?

  13 – 20 μm
• What is the conduction velocity for group II afferent fibres?

  35 – 75 ms
• Which afferent fibre group is the smallest?

  Group III
• What is the conduction velocity for non-myelinated group IV fibres?

  0.5 – 2.0 ms
• What are the sources and effects of key substances in pain pharmacology?

  • Potassium: Damaged cells, Activation
  • Serotonin: Platelets, Activation
  • Bradykinin: Plasma, Activation
  • Histamine: Mast cells, Activation
  • Prostaglandins: Damaged cells, Sensitization
  • Leukotrienes: Damaged cells, Sensitization
  • Substance P: Primary afferent fibres, Sensitization
• What is the role of the spinothalamic tract (STT) in pain transmission?

  Transmits pain signals to the thalamus

  
• What are the main targets for fast pain pathways?

  VPL, VPM, PO
• What are the main targets for slow pain pathways?

  • Spinoreticular tract: Reticular formation
  • Spinomesencephalic tract: Periaqueductal Grey Area (PAG)
  • Paleospinothelamic tract: Reticular formation, PAG, Tectum, NSIN, Other midline nuclei
• How do fast pain STT projections differ from slow pain STT projections in the thalamus?

  Fast pain targets lateral nuclei, slow pain targets medial nuclei
• What is the role of the lateral spinothalamic tract?

  Transmits fast pain and temperature
• What are the differences between direct and indirect pain pathways?

  • Direct (fast-pain):
  • Origin: Laminae I & IV, V
  • Somatotopic organization: Yes
  • Body representation: Contralateral
  • Indirect (slow-pain):
  • Origin: Laminae I, IV, V, VII, VIII
  • Somatotopic organization: No
  • Body representation: Bilateral
• What is the cortical location for fast pain pathways?

  Parietal lobe (SI cortex)
• What is the role of the medial pain system?

  Emotion and memory related to pain
• What are the functions of the pain matrix?

  • Pain localization
  • Pain registration
  • Intensity coding
  • Emotion/Memory
  • Attention
  • Response selection
• What is the effect of serotonin in pain modulation?

  Inhibition of Substance P
• What is the significance of the periaqueductal grey area (PAG) in pain control?

  Central pain control via descending projections
• How do the roles of Aδ and C fibres differ in pain perception?

  Aδ fibres localize pain, C fibres register pain
• What is the function of the spinoreticular tract?

  Transmits slow pain signals
• What is the role of the thalamus in pain perception?

  Relay station for pain signals to the cortex
• What is the function of the reticular formation in pain pathways?

  Modulates arousal and attention to pain
• What is the significance of the dorsal root ganglion in pain transmission?

  Contains primary afferent neurons
• How does the pain matrix integrate sensory and emotional aspects of pain?

  Combines sensory-discriminative and affective components
• What is the role of nociceptors in pain perception?

  Detect noxious stimuli
• What is the effect of bradykinin in pain pathways?

  Activates pain receptors
• What is the source of substance P?

  Primary afferent fibres
• What is the function of the anterior cingulate cortex in pain perception?

  Processes emotional aspects of pain
• How do the functions of the medial and lateral pain systems differ?

  Medial system focuses on emotion, lateral on localization