Tuesday, 4-19-Physiology of Pain (Karius)

Question 1

___ pain is associated with the immediate injury (sharp)

___ pain is characterized as dull or achy, often occurs after the injury

Answer 1

fast

slow

Question 2

what are the 2 types of nociceptor nerve fibers?

Answer 2

• Adelta fibers

- C fibers

Question 3

These nociceptor fibers are small, sparsely myelinated, and associated with fast/sharp pain

Answer 3

Adelta fibers

Question 4

These nociceptor fibers are unmyelinated fibers associated with dull pain (slow pain)

Answer 4

C fibers

Question 5

Mutations in this channel lead to an absence of pain sensation: __

Answer 5

SCN9A or Na 1.7 (Mechanosensitive Na channel)

Question 6

Nociceptors express a number of ligand-gated receptors which alter the sensitivity of the nociceptors to input. These include receptors for: __

Answer 6

• Substance P
• Kinins (bradykinin)
• ATP
• H+

-When these chemicals bind to their receptors, they change the sensitivity of the nociceptors (usually increasing) and activate the silent nociceptors

Question 7

This tract/pathway to the brain is concerned with “fast” pain: ___

This tract/pathway to the brain is concerned with “slow” pain: ___

Answer 7

spinothalamic tract

spinoreticulothalamic system

Question 8

___ fibers release EAA’s as NT acting primarily on non-NMDA receptors

Answer 8

Adelta

Question 9

__ fibers release Substance P and EAA as its NTs

Answer 9

C type

Question 10

Nociceptors that travel with the __ pathway synapse on an interneuron in the SC before crossing and ascending to the RF. This synapse is the site of much modulation of SC function –> Local (gate theory) and descending (opioid pathways)

Answer 10

spinoreticulothalamic

Question 11

Visceral afferents travel with __, rather than with either of the 2 spinal pathways

Answer 11

autonomic nerves

Question 12

___ receive input from the nociceptors and play a role in localizing the pain

Answer 12

S1 and S2

Question 13

The ___ is particularly important in the interpretation of nociceptive inputs. It processes information about the internal state of the body and contributes to the autonomic responses to the pain. It INTEGRATES ALL SIGNALS RELATE TO THE PAIN (ASYMBOLIA)

Answer 13

insular cortex

i.e., sweating, rapid breathing, increase HR and BP; BP increasing due to pain

Question 14

Many nociceptive inputs go to the ___. This is particularly important for activating/producing the emotional components inherent in the sensation of pain

Answer 14

amygdala

Question 15

___ nociceptors, traveling with the autonomic nerves, have additional synapses within the hypothalamus and the medulla

Answer 15

visceral

-these additional synapses form the basis of the physiological changes associated with visceral pain, including diaphoresis and altered BP

Question 16

How does rubbing the area of skin activated by the Abeta fiber reduce sensation of pain?

Answer 16

activation of an Abeta fiber by normal stimuli (pain) –> Abeta fiber releases EAA and activates an inhibitory interneuron in the SC –> Inhibitory interneuron releases Glycine to inhibit activity of 2nd order neuron in the pain pathway

Question 17

Descending influences can physiologically modify pain:

1) Neurons in the ___ are activated by numerous inputs, including opiate, EAA, and the cannibinoids –> 2) Axons from step 1 travel to the midline Raphe Nuclei and release ___, which activate the raphe neurons –> 3) Axons from the raphe neurons travel to the SC and release ___, which activate inhibitory interneurons, causing them to release opiates –> 4) the opiates released by the interneuron activate __ receptors on the presynaptic terminal of the C fiber –> 5) This produces pre-synaptic inhibition that reduces the release of ___ from the nociceptor and reduces pain transmission

Answer 17

1) Periaqueductal gray
2) enkephalins
3) serotonin
4) mu
5) substance P

Question 18

Deep pain is associated with periosteum, ligaments, is usually dull/achy. It has few __ fibers and many __ fibers. They are associated with muscle spasm

Answer 18

few Adelta fibers

Many C fibers

Question 19

Muscle pain is caused by injury or ischemia during contraction, has both Group ___ fibers present, and gets both fast and slow pain associated with muscle.

Answer 19

III and IV

Question 20

Visceral pain is poorly localized, has few receptors and mostly group __ receptors, activated by stretch receptors (distention) and is often referred

Answer 20

IV