Chapter 13 - Touch 4

Question 1

What is pain

Answer 1

• perceptual consequence of nociception
• important survial value
• highly subjective state - sensory, emotional, cognitive influences togehter

Question 2

Steps to process nociceptive signals in dorsal horn

Answer 2

1. nociceptive signals arrive at the dorsal horn of the spinal cord in the second layer, the substatia gelatinosa
2. interneurons in the dorsal horn recieve info from the brain
3. interneurons form synapses on neurons that convey nociceptive info to the brain

Question 3

Gate control theory

Answer 3

How various influences integrate to form pain perception
- bottom-up pain signals can be blocked via a feedback circuit in the dorsal horn

Inhibitory interneuron acts as gates to determine how effective nociceptive signals are in activating projection neurons

Second order neuron of antelaroral pathway

influences from brain and fibers converge upon spinal cord andmodulate transmission of incoming pain signasl thru C fibers

Question 4

Which Neurons respond to Pain processing

Answer 4

• complex cluster of areas that respond to aspects of pain
• discriminative aspects
  emotional aspects
• ACC - attention alloacation
• prefontal cortex - cognition, control
• amygdala - emotional, memory, fear

Question 5

Disorders of internal organs

Answer 5

referred pain - pain that happens in deeper structures of the body is actually felt elsewhere (due to convergence of afferent fibers onto the spinal cord from different body parts)

Question 6

How pain is measured

Answer 6

1. Univariative approach - group all dimensions of pain together, measure using standard psychophysical techniques (JND)
2. Multivaraitve approach - separately asses different dimensions of pain (questionnaire)

Question 7

Pain sensitization

Answer 7

Peripheal - results from interaction of afferent nociceptors with inflammatory substances released after tissue damage

Central - increased excitability of neurons at the dorsla horn
-phatom limb is an example - no signalling but overreactive neurons

Hyperalgesia - increaed pain to a normally painful stim

Neurpathic pain - chronic intensely painful experience is too difficult to res

Question 8

methods for pain

Answer 8

Analgesics – removes pain
Blocks voltage gated sodium channels so blocking AP to happen so they can’t send pain info
(not) Anesthetic – removes all feelings

Anti-inflammatory drugs – reduce inflammation

Opiates – blocks pain signals in spinal cord
Mimic the effects of biological endorphins
Higher endorphins = higher pain tolerance
Highly addictive

Question 9

Methods for existng moderate pain

Answer 9

Surgical and neurostimilary approach - remove part of spinal cord (cordotomy) or part of frontal lobe (lobotomy)
- TENS - activates A beta fibres

Psychological approach
- counter stim
- placebo
relaxation

Question 10

Itch

Answer 10

• receptors are pruiceptors
• C fiberes convey through spinothalmic system
• activated by pruigenic chemicals liek hisamine

interactions with itch and pain
- some itch respond to pain

• scratching may redcue itchiness because of inhibit it activates A beta fibres, releases dopamine

Question 11

Features of thermosensation

Answer 11

Absolute threshold depens on:
- rate of change, size of skin area, actual body temp. body locaton

Adaptation is a prominent feature of thermal sensation