Touch and pain - Vocabulary Noba Flashcards
What are A-fibers?
Fast-conducting sensory nerves with myelinated axons, large diameter, and thicker myelin sheaths. Aβ-fibers conduct touch signals (80 m/s, 10 μm diameter), Aδ-fibers conduct cold, noxious, and thermal signals (12 m/s, 2.5 μm diameter), and Aα-fibers conduct proprioceptive information (120 m/s, 20 μm diameter).
What is allodynia?
Pain caused by a stimulus that does not normally provoke pain, such as a light, stroking touch.
What is analgesia?
Pain relief.
What are C-fibers?
Slow-conducting unmyelinated sensory afferents (1 μm diameter, 1 m/s conduction velocity). C-pain fibers convey noxious, thermal, and heat signals; C-tactile fibers convey gentle touch and light stroking.
What is chronic pain?
Persistent or recurrent pain, beyond the usual course of acute illness or injury, sometimes present without observable tissue damage or clear cause.
What do C-pain or Aδ-fibers convey?
Noxious, thermal, and heat signals.
What do C-tactile fibers convey?
Gentle touch and light stroking.
What are cutaneous senses?
The senses of the skin: tactile, thermal, pruritic (itchy), painful, and pleasant.
What is the descending pain modulatory system?
A top-down system that inhibits or facilitates pain via endogenous opioids. Involves brain structures like the anterior cingulate cortex, amygdala, hypothalamus, and the periaqueductal grey (PAG), projecting to the spinal dorsal horn.
What are endorphins?
Endogenous morphine-like peptides binding to opioid receptors in the brain and body.
What is exteroception?
The sense of external stimuli originating from outside the body.
What is interoception?
The sense of the physiological state of the body, including hunger, thirst, pain, and other sensations relevant to homeostasis.
What is nociception?
The neural process of encoding noxious stimuli, independent of pain experience.
What are nociceptors?
High-threshold sensory receptors that encode noxious stimuli, signaling tissue damage. Nociception can occur without pain.
What is a noxious stimulus?
A stimulus that damages or threatens damage to normal tissues.
What is the social touch hypothesis?
A theory that C-tactile afferents distinguish social touch, sending affective signals parallel to Aβ-fibers, processed in brain areas like the insula.
How is pain defined?
An unpleasant sensory and emotional experience associated with actual or potential tissue damage.
What is phantom pain?
Pain that appears to originate from an amputated limb.
What is the placebo effect?
Effects caused by the meaning ascribed to a treatment, not its physical properties. It often involves opioid mechanisms.
What is sensitization?
Increased responsiveness of nociceptive neurons to normal or subthreshold inputs, occurring in the central or peripheral nervous system.
What is the somatosensory cortex?
Composed of the primary sensory cortex (S1) in the postcentral gyrus and secondary sensory cortex (S2) in the parietal operculum and parts of the insula.
What does “somatotopically organized” mean?
Body parts are represented in the brain topographically according to their physical location.
What is the spinothalamic tract?
A pathway that transmits pain and temperature signals to the thalamus, involving C-fibers and neurons crossing the spinal cord.
What is transduction?
The process of converting stimuli into electrical signals for nervous system processing.
