Pathophysiology of pain and Pharmacology of Opiates

Question 1

What are the functions of pain?

Answer 1

• Aid in repair (hypersensitivity)
• Warning system (avoid injury)
• Can be maladaptive (e.g. irreversible neuropathy)

Question 2

What are the temporal features of pain?

Answer 2

• Onset
• Duration
• Course
• Pattern

Question 3

What types of pain quality are associated with inflammatory pain?

Answer 3

Throbbing, pulsating

Question 4

What types of pain quality are associated with neuropathic pain?

Answer 4

Stabbing, shooting, burning, tingling

Question 5

What types of pain quality are associated with visceral pain?

Answer 5

Squeezing

Question 6

What is referred pain?

Answer 6

Pain that is perceived at a location different from the site of the painful stimulus

Question 7

What are the three different types of pain fibers?

Answer 7

• Aβ-fibers
• Aδ-fibers
• C-fibers

Question 8

What is the function of Aβ-fibers?

Answer 8

Transmit non-noxious (touch and pressure),Innervate the skin
Faster, (35-75 m/s)

Question 9

What is the function of Aδ-fibers?

Answer 9

Pain, cold
Myelinated, Fast (2-35 m/s)
“First pain”, refl ex arc
Sharp, prickly

Question 10

What characterizes C-fibers?

Answer 10

Pain, Temp, Touch, pressure, Itch (polymodal)
 Unmyelinated
 Slow (0.5-2 m/s)
 “Second pain”
 dull, aching

Question 11

What is peripheral sensitization?

Answer 11

Reduced firing threshold due to repeated stimuli. increase expression of pain receptors

Question 12

What role does substance P play in pain?

Answer 12

heightens pain response
1.Vasodilation
2.Degranulation of mast cells
3.Release of histamine
4.Inflammation and prostaglandins

Question 13

What might contribute to neuropathic pain sensitization through spontaneous afferent activity?

Answer 13

• Enhanced expression of sodium channel subtypes
• Ectopic action potentials

Question 14

Where is there high expression of opioid receptors?

Answer 14

In the brain stem along the descending pathway

Question 15

True or False: Pain is solely a physical sensation.

Answer 15

False

Pain is also an emotion that impacts mood.

Question 16

Locations of pain

Answer 16

Focal, multifocal, generalized, referred, superficial, deep
Opioid induced hyperalgesia (generalized)

Question 17

pain transmission

Answer 17

central effect, spinal cord, and periphery

Question 18

Temperature sensitive peripheral receptors involved in pain signaling

Answer 18

Transient receptor potential cation channel (TRP)
TRPV (Vanniloid) = Heat
TRPM (Melastatin) = cold

Question 19

Acid sensitive receptors

Answer 19

 Acid sensing ion channel (ASIC)
 Activated by H+
 Conduct Na+

Question 20

Chemical irritant sensitive

Answer 20

 Histamine
 Bradykinin

Question 21

T or F: chronic pain is >1 month

Answer 21

False >3months

Question 22

what are the types of chronic pain

Answer 22

nociceptive (inflammatory) , neuropathic, visceral(inflammatory), and mixed

Question 23

What are the two types of neuropathic pain

Answer 23

central (post stroke, SPI, migraine)
Peripheral (post-herpetic, diabetic neuropathy)

Question 24

what types of pain are associated with nociceptive

Answer 24

osteoarthritis, osteosarcoma skin/deep tissue

Question 25

T or F: pain is an emotion that impacts mood

Answer 25

T

Question 26

How does pain transmission work in periphery

Answer 26

pain in joint--> activation of peripheral NS--> transmission--> activation of CNS at spinal cord-->input-->transmission of the pain signal to brain

Question 27

How does reflex upon painful stimuli work

Answer 27

skin-> afferent nerve--> spinal cord--> efferent nerve--> muscle

Question 28

how does spinal sensitization contribute to neuropathic pain sensitization

Answer 28

Neuropeptides,CGRP, and substance P bind receptors increasing PLC and PKC which increase AMPA and NMDA expression and sensitivity

Question 29

T or F: there is a low expression of opioid receptors in the brain stem along the descending pathway

Answer 29

False high expression, endogenous opioid stimulate descending inhibition

Question 30

Mu opioid receptors in the brain action

Answer 30

alter mood produce sedation reduce emotional reaction

Question 31

Mu opioid receptors in the brainstem action

Answer 31

increase activity of descending fibers

Question 32

Mu opioid receptors in the spinal cord action

Answer 32

inhibit vesicle release hyperpolarize post-synaptic membrane

Question 32

Mu opioid receptors in the periphery action

Answer 32

reduce activation of primary afferent modulate immune activity

Question 33

Prefrontal cortex and pain

Answer 33

active when trying to reduce pain

Question 33

Medial Prefrontal gyrus and pain

Answer 33

heightened activity in anxious people

Question 34

Nucleus accumbens and pain

Answer 34

release DA and serotonin

Question 35

Amygdala and pain

Answer 35

anticipates pain

Question 36

thalamus and pain

Answer 36

recieves pain signals

Question 37

anterior cingulate cortex and pain

Answer 37

registers unpleasant feelings when things go wrong either physically or emotionally

Question 38

Somatosensory cortex and pain

Answer 38

registers which body part is in pain and the intensity of that pain