Pain

• What is the definition of pain according to the International Association for the Study of Pain?

  Pain is an unpleasant sensory and emotional experience.
• What are the reasons for feeling pain?

  • Gives conscious awareness of tissue damage
  • Provides protection by removing body from danger
  • Promotes healing by preventing further damage
  • Elicits behavioral and emotional responses
• What are nociceptors?

  Special receptors that respond to noxious stimuli.
• What types of stimuli do nociceptors respond to?

  They respond to thermal, mechanical, electrical, and chemical stimuli.
• What is nociceptive pain processing?

  • Transduction to perception
  • Noxious stimuli sensed by specific receptors
  • Signals conveyed by Aδ and C fibers to spinal dorsal horn
  • Processed and transmitted to the brain
• What is inflammatory pain?

  Pain caused by tissue injury and mediators.
• What is neuropathic pain?

  Pain caused by a lesion or disease of the nervous system.
• What are the types of hyperalgesia?

  • Primary hyperalgesia: occurs in damaged tissue
  • Secondary hyperalgesia: occurs in surrounding tissues
• What is peripheral sensitization?

  Nociceptors change in response to tissue injury.
• What is central sensitization?

  Changes in the dorsal horn and brain affecting pain perception.
• What are the ascending tracts involved in pain processing?

  • Dorsal columns: cross in the medulla
  • Spinothalamic tract: crosses in the ventral white commissure
• What is fast pain?

  Sharp pain occurring rapidly after stimuli.
• What is slow pain?

  Pain that begins slowly and increases in intensity.
• What characterizes visceral pain?

  • Accompanied by strong autonomic reflexes
  • Poorly localized and may be referred
  • Mostly caused by distension or ischemia
• What is referred pain?

  Pain from organs perceived as coming from skin.
• How does the gate control theory explain pain relief?

  • Rubbing the area activates touch fibers
  • Touch fibers inhibit pain pathways in the dorsal horn
  • Decreases action potential and pain severity
• What is the descending analgesic system?

  • Involves nuclei rich in serotonin and epinephrine
  • Releases endogenous opioids to inhibit pain
  • Stimulates periaqueductal gray matter
• What are applications of the pain gate theory?

  • TENS (transcutaneous electrical nerve stimulation)
  • Acupuncture
  • Massage
• What do aspirin and ibuprofen block?

  Formation of prostaglandins that stimulate nociceptors.
• What does Novocain block?

  Conduction of nerve impulses along pain fibers.
• How is pain sensation from the face and mouth processed?

  Through trigeminal nerve branches to the thalamus.
• What are the branches of the trigeminal nerve involved in pain sensation?

  • V1: Ophthalmic branch
  • V2: Maxillary branch
  • V3: Mandibular branch
• What happens to nociceptive information after it reaches the thalamus?

  • It is projected to the primary somatosensory cortex for processing.