Pain And Temperature - 20

Question 0

Define nociception

Answer 0

It is the activation of specialized sensory receptors that provide information about damaged tissue

Question 1

Define pain

Answer 1

It is the perception of an aversive or unpleasant sensation from a specific region of the body can be categorized as fast or slow

Question 2

List the four types of nociceptors

Answer 2

Thermal, mechanical, chemical, polymodal

Question 3

Which nociceptors are thinly myelinated Adelta with rapid conduction speed?

Answer 3

Thermal and mechanical

Question 4

Describe what thermal nociceptors respond to.

Answer 4

Extreme temperatures of > 45°C or < 5°C

Question 5

Describe what mechanical nociceptors respond to.

Answer 5

Extreme or intense pressure

Question 6

Which types of fibers make up polymodal nociceptors?

Answer 6

small diameter unmyelinated C fibers that conduct the signal very slowly (<1m/s)

Question 7

What do chemical nociceptors respond to?

Answer 7

Chemicals released by damaged cells

Question 8

What do polymodal nociceptors respond to?

Answer 8

High intensity stimuli of one or more of a variety of thermal, mechanical, or chemical

Question 9

What descriptors are used for fast pain, from where in the body? And how quickly is it perceived?

Answer 9

Described as being sharp acute or electric associated with sensations in the skin. Perception of this pain occurs quickly within .1 seconds of stimulus onset.

Question 10

Which receptors are associated with fast pain?

Answer 10

Thermal and mechanical receptors, Adelta

Question 11

What descriptors are used for slow pain, from where in the body? And how quickly is it perceived?

Answer 11

Slow pain is described as being throbbing or burning and is associated with sensations that occur in deep tissues like organs but also sometimes with skin. Perception of this pain occurs slowly, within one second of stimulus onset.

Question 12

Which receptors are associated with slow pain?

Answer 12

Polymodal nociceptors, Unmyelinated C fibers

Question 13

How do nociceptors differ from other receptors? Hint adaptation

Answer 13

Nociceptors, unlike other receptors, are non-adapting. They will continue to fire at the same rate in the presence of a steady continuous stimulus. Some nociceptors actually increase their firing rate to a constant stimulus, this is called hyperalgesia.

Question 14

Which fibers carry which temperature nociceptors?

Answer 14

Type C fibers carry warm and type Adelta fibers carry cold

Question 15

Where do the DRG axons for temperature nociception synapse? Then where do these in turn synapse? And where do they ascend?

Answer 15

DRG afferent axons synapse on interneurons in laminae 1, 2 and 3, which in turn synapse on second order neurons in 5. Then the second order neurons ascend in the ALS

Question 16

Which pain pathways for fast pain? And which fiber

Answer 16

Lateral spinothalamic with A Delta fibers

Question 17

Explain the fast pain pathway for the body/extremities

Answer 17

DRG axons enter the dorsal horn and ascend 2-3 levels in Lissauer’s tract then synapse on second order neurons in one and five which are nociceptive specific and wide dynamic range neurons. The second order axons then cross the midline in the anterior white commissure and ascend in the ALS to the VPL in thalamus then project to the pain areas of the cortex.

Question 18

Explain the fast pain pathway for the face

Answer 18

The CN V (Trigeminal) DRG enters the dorsal column in the pons and descends to the trigeminal nucleus in the medulla. The axon then decussates and becomes the trigeminothalamic tract and ascends to the thalamus VPM The axons from the neuron there projects to the face part of the homunculus in the somatosensory cortex.

Question 19

What happens after a complete transection of the ALS?

Answer 19

Severe loss of pain and temperature sensation contralaterally

Question 20

What happens with a partial lesion to the ALS?

Answer 20

Can result in severe pain sensation. Central pain syndrome or thalamic syndrome which causes spontaneous burning pain. Dysesthesia