Touch and pain - Vocabulary Noba

Question 1

What are A-fibers?

Answer 1

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).

Question 2

What is allodynia?

Answer 2

Pain caused by a stimulus that does not normally provoke pain, such as a light, stroking touch.

Question 3

What is analgesia?

Answer 3

Pain relief.

Question 4

What are C-fibers?

Answer 4

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.

Question 5

What is chronic pain?

Answer 5

Persistent or recurrent pain, beyond the usual course of acute illness or injury, sometimes present without observable tissue damage or clear cause.

Question 6

What do C-pain or Aδ-fibers convey?

Answer 6

Noxious, thermal, and heat signals.

Question 7

What do C-tactile fibers convey?

Answer 7

Gentle touch and light stroking.

Question 8

What are cutaneous senses?

Answer 8

The senses of the skin: tactile, thermal, pruritic (itchy), painful, and pleasant.

Question 9

What is the descending pain modulatory system?

Answer 9

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.

Question 10

What are endorphins?

Answer 10

Endogenous morphine-like peptides binding to opioid receptors in the brain and body.

Question 11

What is exteroception?

Answer 11

The sense of external stimuli originating from outside the body.

Question 12

What is interoception?

Answer 12

The sense of the physiological state of the body, including hunger, thirst, pain, and other sensations relevant to homeostasis.

Question 13

What is nociception?

Answer 13

The neural process of encoding noxious stimuli, independent of pain experience.

Question 14

What are nociceptors?

Answer 14

High-threshold sensory receptors that encode noxious stimuli, signaling tissue damage. Nociception can occur without pain.

Question 15

What is a noxious stimulus?

Answer 15

A stimulus that damages or threatens damage to normal tissues.

Question 16

What is the social touch hypothesis?

Answer 16

A theory that C-tactile afferents distinguish social touch, sending affective signals parallel to Aβ-fibers, processed in brain areas like the insula.

Question 17

How is pain defined?

Answer 17

An unpleasant sensory and emotional experience associated with actual or potential tissue damage.

Question 18

What is phantom pain?

Answer 18

Pain that appears to originate from an amputated limb.

Question 19

What is the placebo effect?

Answer 19

Effects caused by the meaning ascribed to a treatment, not its physical properties. It often involves opioid mechanisms.

Question 20

What is sensitization?

Answer 20

Increased responsiveness of nociceptive neurons to normal or subthreshold inputs, occurring in the central or peripheral nervous system.

Question 21

What is the somatosensory cortex?

Answer 21

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.

Question 22

What does “somatotopically organized” mean?

Answer 22

Body parts are represented in the brain topographically according to their physical location.

Question 23

What is the spinothalamic tract?

Answer 23

A pathway that transmits pain and temperature signals to the thalamus, involving C-fibers and neurons crossing the spinal cord.

Question 24

What is transduction?

Answer 24

The process of converting stimuli into electrical signals for nervous system processing.