Physiology of Pain Karius

Question 1

What is fast pain associated with?

Answer 1

immediate injury

sharp pain

Question 2

What is slow pain associated with?

Answer 2

dull or achy pain

occurs after the injury

Question 3

Pain characterized by location

Answer 3

deep, muscle, visceral, somatic/cutaneous

Question 4

Sensory Receptor characteristics

Answer 4

base nerve endings with ion channels that open in response to stimuli

Question 5

Two types of nociceptor fibers

Answer 5

Adelta and C fibers

Question 6

A delta fiber characteristics

Answer 6

small, sparsely myelinated

fast, sharp pain

Question 7

C fiber characteristics

Answer 7

unmyelinated

slow, dull pain

Question 8

Types of Nociceptors

Answer 8

sensitive to thermal and mechanical
sensitive to only thermal
sensitive to only mechanical
silent/sleeping

Question 9

Silent/sleeping nociceptors

Answer 9

detect pain to same spot
ex. if I hit my hip against table and then a day later I hit it again
not active under most conidions

Question 10

Mutations in mechanosensitive Na+ channel

Answer 10

lead to absence of pain sensation or paroxysmal pain syndrome

Question 11

Paroxysmal pain syndrome

Answer 11

experience overwhelming pain but nothing happened to cause it

Question 12

Function of ligand gated channels on nociceptors

Answer 12

alter sensitivity of the nociceptors to input

Question 13

What receptors are associated with ligand gated channels?

Answer 13

Substance P, kinins (bradykinin), ATP, H+

Question 14

What happens when substance P, bradykinin, ATP, and H+ receptors are bound to?

Answer 14

activate silent nociceptors

change the sensitivity of nociceptors

Question 15

Spinothalamic tract to the brain

Answer 15

fast pain

Question 16

Spinoreticulothalamic system to brain

Answer 16

slow pain

Question 17

How does the spinal cord sense noxious stimuli from A delta fibers?

Answer 17

release EAA (NT) from A delta fibers which act on non-NMDA receptors

Question 18

How does the spinal cord sense noxious stimuli from C fibers?

Answer 18

substance P and EAA

Question 19

Pathway of spinoreticulothalamic pathway

Answer 19

slow pain

nociceptors synapse on interneuron in spinal cord before crossing and ascending to the reticular formation

Question 20

What can modify the spinoreticulothalamic pathway?

Answer 20

opiods and sensory information

Question 21

How can modulations of spinoreticulothalamic be made?

Answer 21

local (gate theory)

descending (opiod pathway)

Question 22

How is visceral pain sensed?

Answer 22

visceral afferents travel with autonomic nerves

has some synapses in the hypothalamus and medulla

Question 23

Where is nociceptive input distributed in the brain’s cortex?

Answer 23

thalamus, mediofrontal cortex, post-central gyrus, insular cortex
this makes pain impossible to ignore

Question 24

S1 and S2 input on processing of pain in the brain

Answer 24

receive input from nociceptors and play a role in localizing pain

Question 25

How does the insular cortex process of pain in the brain

Answer 25

Interpretation of nociceptive inputs Process internal state of body "yes everything is okay or no everything is not okay" Autonomic response to pain "sympathetic reaction" Integrates all signals related to pain (asymbolia)

Question 26

Asymbolia

Answer 26

have physiological signs of pain but can't describe it

Question 27

What happens to pain if there is a lesion in one area that pain is perceived?

Answer 27

does NOT abolish ability to experience pain but the pain experience will change

Question 28

Amygdala impact on pain

Answer 28

receives nociceptive input | important in activating/producing emotional components of pain sensation

Question 29

Clinical significance of synapses in the hypothalamus and medulla for visceral afferents

Answer 29

form basis of physiological changes associated with visceral pain like diaphoresis and altered blood pressure

Question 30

What is the Gate Theory of Pain and how does it work?

Answer 30

Other somatic input can alleviate the pain | Stimulating other senses by changing what info is going to the brain

Question 31

Pathway for gate theory of pain

Answer 31

activate second stimuli (A beta) which will synapse on same interneuron as initial stimuli (A delta or C fiber)

Question 32

What does A beta release to interneuron?

Answer 32

EAA that activates an inhibitory interneuron in the spinal cord

Question 33

What does the inhibitory interneuron release in the gate theory of pain?

Answer 33

glycine to inhibit activity of second order neuron that was initially attached to the interneuron from the A delta/C fiber hyperpolarizes it

Question 34

End result of gate theory of pain?

Answer 34

reduce sensation of pain

Question 35

Descending Mechanism to modify painful inputs

Answer 35

use presynaptic inhibition to reduce activation of second-order nociceptive neuron in spinal cord

Question 36

Step 1 in Pathway for descending influence

Answer 36

Neurons in periaqueductal gray are activated but opiates, EAA, and CB1 cannibinoids

Question 37

Step 2 in Pathway for descending influence

Answer 37

axons from periaqueductal neurons travel to raphe nuclei and release enkephalins and activate raphe neurons

Question 38

Step 3 in Pathway for descending influence

Answer 38

axons from raphe neurons travel to spinal cord and release serotonin which activate inhibitory interneurons causing them to release opiates

Question 39

Step 4 in Pathway for descending influence

Answer 39

Opiates activate receptors on presynaptic terminal of C fiber

Question 40

Step 5 in Pathway for descending influence

Answer 40

*main step* | produces pre-synaptic inhibition that reduces release of substance P from nociceptor and reduce pain transmission

Question 41

Skin pain innervation

Answer 41

both A delta and C fibers

Question 42

Deep pain

Answer 42

periosteum and ligaments dull, achy many C fibers associated with muscle spasm

Question 43

Muscle pain

Answer 43

injury or ischemia during contraction both A and C fibers both fast and slow pain in muscle

Question 44

Visceral pain characteristics

Answer 44

poorly localized C fibers stretch receptors often referred

Question 45

How does visceral pain develop

Answer 45

Brian is taught that the shoulder is more likely to experience pain than the heart, the nociceptors may converge on the same interneuron of the spinal cord

Question 46

Pneumonia visceral pain

Answer 46

in the lung and the diaphragm so pain is felt in the upper left quadrant