Pain

Question 1

Physiology of Pain

Answer 1

Nociceptors

Question 2

Nociceptors

Answer 2

i. Specialized “free” neurons
ii. Respond to potentially damaging stimuli
iii. Most not myelinated
iv. When does it cross contralaterally?

Question 3

Nociceptors

Answer 3

1. They cross over immediately, at the spinal cord, which
   means they evolved at different time from myelinated
   neurons because they cross at the medulla

Question 4

Several brain structures involved

Answer 4

Anterior cingulate cortex (emotional)
1. Tylenols studies
a. Looks at students who have been dumped recently,
one group took max dose of tylenol once a day for
a month while the other group was the control and
took a placebo.
b. Those who took tylenol were significantly less
depressed in comparison to those who took
placebo. This was replicated as well and same
results were found.

Question 5

Somatosensory Cortex (sensory)

Answer 5

1. Helps find where pain is located

Question 6

PAG

Answer 6

1. Has receptors for substance P, big dopamine producing
   center

Question 7

Gate Theory

Answer 7

Why does rubbing a wound relieve pain?

Question 8

Why does rubbing a wound relieve pain?

Answer 8

i. Small C fibers (nociceptors) activated during pain;
ii. Regular large fibers do not carry pain
iii. Rubbing activates large fibers which covers up the pain coming
from the small C fibers

Question 9

Gate Theory

Answer 9

1. Closes pain “gate” in spinal cord
2. Gate theory probably BS
3. Better explanation: increases endorphins

Question 10

Stimulation produced analgesia

Answer 10

1. Based on same idea on rubbing something constantly
2. Transcutaneous electrical nerve stimulation (TENS)

Question 11

“Congenital insensitivity to pain with anhidrosis” (CIPA)

Answer 11

a. They don’t have any nociceptors or c nerve fibers
b. Cannot sweat
c. Doesn’t sneeze or cough, never scratches an itch
d. Type of HSAN, another name for this

Question 12

Endorphins

Answer 12

a. Bind to PAG in midbrain
b. Block release of “substance P” by nociceptors
c. Opiates bind to same receptors
i. Morphine, oxycodone, codeine, fentanyl

Question 13

Other ways to increase endorphins?

Answer 13

i. Exercise
ii. Laughter
iii. Orgasm
iv. Acupuncture?