4.4 COPY 2nd half of deck/pain

Question 1

Visceral pain in the pharynx, larynx, trachea, and upper esophagus is transmitted via ___ ____, ____ & ____which also carry parasympathetic nerve fibers

Answer 1

Visceral pain in the pharynx, larynx, trachea, and upper esophagus is transmitted via ___, which also carry parasympathetic nerve fibers
cranial nerves IX and X

Question 2

Visceral pain in the distal colon, rectum, urinary bladder, and testes or cervix is transmitted via ___ ___, ___-____which also carry parasympathetic nerve fibers

Answer 2

spinal nerve S2-S4 -

Question 3

Visceral pain in most organs of the thorax and abdomen is transmitted via ___ _____(e.g., splanchnic nerves) into the spinal cord

Answer 3

sympathetic nerves

Question 4

Characteristics of visceral pain:

Answer 4

Characteristics of visceral pain:

a. Extreme unpleasantness, aching, or burning
b. Poorly localized
c. Typically referred to the body surface

Question 5

The CNS has modulatory circuits at many levels (cerebrum, diencephalon, midbrain, pons, medulla and spinal cord) whose function is to alter the ____

Answer 5

perception of pain

Question 6

G protein-coupled opioid receptors are involved in modulating ___

Answer 6

pain perception

Question 7

Opioids (i.e., enkephalin and endorphins) are generally released from ___

Answer 7

inhibitory interneurons

Question 8

Presynaptically, opioid receptor activation causes closure of ___, which depresses neurotransmitter release

Answer 8

Presynaptically, opioid receptor activation causes closure of ___, which depresses neurotransmitter release
closure of voltage gated Ca2+ channels

Question 9

Postsynaptically, opioid receptor activation opens ___, resulting in IPSPs and inhibition of action potential firing

Answer 9

Postsynaptically, opioid receptor activation opens ___, resulting in IPSPs and inhibition of action potential firing
ligand gated K+ channels -

Question 10

The initial site of CNS pain modulation is in ____

Answer 10

the dorsal horn of the spinal cord

Question 11

According to this theory, nociceptive afferents are modified by non-nociceptive (typically tactile) afferents
initial site/dorsal horn

Answer 11

gate control theory

Question 12

Enkephalin binds to opioid receptors on both the ___ (i.e., C fiber nociceptive afferent) and the ____ (excitatory interneuron) neuron.

Answer 12

Enkephalin binds to opioid receptors on both the ___ (i.e., C fiber nociceptive afferent) and the ____ (excitatory interneuron) neuron.
presynaptic, postsynaptic

Question 13

Presynaptic effects of Enkephalin:

enkephalin-endogenous opioid

Answer 13

(i) Closure of voltage-gated Ca2+ channels
(ii) ↓ neurotransmitter release
(iii) Less nociceptive information sent up the spinothalamic tract

Question 14

Involves a ____ and a ____ that synapses on enkephalin- secreting, inhibitory interneuron. The nociceptive afferent and the inhibitory interneuron synapse on the same excitatory interneurons. If the faster-conducting, tactile Aβ fibers are activated concurrently with slower-conducting, nociceptive C fibers, the inhibitory interneurons are activated more often. The net is less transmission of pain information to the brain.

Answer 14

Mechanism of the gate control theory:
Involves a __nociceptive afferent__ and a _ tactile afferent___ that synapses on enkephalin- secreting, inhibitory interneuron. The nociceptive afferent and the inhibitory interneuron synapse on the same excitatory interneurons. If the faster-conducting, tactile Aβ fibers are activated concurrently with slower-conducting, nociceptive C fibers, the inhibitory interneurons are activated more often. The net is less transmission of pain information to the brain.

Question 15

Postynaptic effects of Enkephalin:

Answer 15

Postynaptic effects of Enkephalin:

(i) Opening of voltage-gated K+ channels
(ii) Hyperpolarization (i.e., IPSP) of the postsynaptic neuron.
(iii) Decreased probability of activating an action potential in the spinothalamic tract.

Question 16

____ is often referred to as the “fast pain” or “discriminative” or “lateral” pain pathway

Answer 16

The spinothalamic tract - Ascending fast pain pathway

Question 17

The spinothalamic tract brings fast pain primarily to the ____. Most fibers are of the Aδ variety (discriminative nociception) or C fibers for detecting heat

Answer 17

The spinothalamic tract brings fast pain primarily to the ____. Most fibers are of the Aδ variety (discriminative nociception) or C fibers for detecting heat
somatosensory cortex -

Question 18

Acute pain is typically both ____. The slow pain aspect of acute pain is carried by these slow pain pathways while fast pain is carried by the spinothalamic tract (a 3 neuron pathway)

Answer 18

fast and slow

Question 19

These pathways terminate on ____ of the CNS (brain stem, portions of the limbic system or non-somatosensory regions of the cortex).

Answer 19

These pathways terminate on ____ of the CNS (brain stem, portions of the limbic system or non-somatosensory regions of the cortex).
medial aspects - Slow pain pathways typically utilize unmyelinated, polymodal C fibers (slow)

Question 20

The slow pain pathways do not always utilize 3 neurons like the spinothalamic tract but they do tend to run alongside it and are also located in the ____ of the spinal cord

Answer 20

anterolateral columns -

Question 21

Since slow pain pathways do not terminate on the somatosensory cortex, they are not __ __ regarding the source of the pain, they are the “diffuse” pathways

Answer 21

well- mapped -

Question 22

There are three slow pain pathways:
SM
SR
SE

Answer 22

There are three slow pain pathways: ascending Spinomesenphalic
Spinoreticular
Spino-emotional

Question 23

Terminates at the midbrain (periaqueductal gray [PAG])
PAG activates descending pathways to modulate incoming pain signals

Spinomesenphalic
Spinoreticular
Spino-emotional

Answer 23

Spinomesenphalic

Question 24

Terminates at the brainstem’s reticular formation (center for arousal, attention & sleep-wake cycles)
Thus, slow pain draws attention to the pain and may interrupt sleep

Spinomesenphalic
Spinoreticular
Spino-emotional

Answer 24

Spinoreticular

Question 25

These pathways receive input from ascending pathways and then send signals back down to the spinal cord in order to inhibit the ascending pain signals.

Answer 25

Descending pain pathways

Question 26

Three primary descending pain modulation tracts:

Answer 26

Raphespinal tract
Ceruleospinal tract
Unnamed tract originating in the Periaqueductal Gray (PAG

Question 27

choices
Ceruleospinal tract or Raphespinal tract

Originates in the raphe nucleus of the upper medulla
Receives innervation from the spinoreticular tract and from the Periaqueductal Gray (PAG)
Secretes serotonin
Synapses on an inhibitory interneuron (enkephalin-secreting) that eventually inhibits the ascending pathways

Answer 27

Raphespinal tract

Question 28

choices
Ceruleospinal tract or Raphespinal tract

Originates in the locus coeruleus (“blue spot”) at the junction of the midbrain and the pons
Receives innervation from the spinoreticular tract and from the Periaqueductal Gray (PAG)
Secretes norepinephrine (NE)
Synapses on and suppresses the nociceptive C afferent via presynaptic inhibition
Mechanism of presynaptic inhibition involves α2 receptors, which activate Gi
inhibits voltage-gated Ca2+ channels (i.e., ICa) leads to ↓ norepinepherine release

Answer 28

Ceruleospinal tract

Question 29

Electrical stimulation of ___ produces “electrical analgesia” sufficient to perform surgery on anaesthetized animals

Answer 29

the PAG

Question 30

Neurons here send their axons down to the raphe nucleus and the locus coeruleus and make excitatory connections
Receives innervation from the spinomesenphalic tract and indirectly from the spinoemotional tract
Stimulation of this area causes profound analgesia without the loss of the other modalities of somatosensation (e.g., proprioception, discriminative touch, etc.).

Answer 30

Unnamed tract originating in the Periaqueductal Gray (PAG)
Neurons here send their axons down to the raphe nucleus and the locus coeruleus and make excitatory connections
Receives innervation from the spinomesenphalic tract and indirectly from the spinoemotional tract
Stimulation of this area causes profound analgesia without the loss of the other modalities of somatosensation (e.g., proprioception, discriminative touch, etc.).

Question 31

Microinjection of ____ into the PAG inhibits GABAergic inhibitory interneurons that tonically suppress the PAG

Answer 31

morphine

Question 32

Microinjection of ___ into the PAG reverses the effects of systemically administered morphine

Answer 32

naloxone

Question 33

Members of the limbic system ____, ____ and ____ are key centers in this level of antinociception;expectations, excitement, distractions and placebos can all play a role in this pathway

Answer 33

Members of the limbic system ____, ____ and ____ are key centers in this level of antinociception;expectations, excitement, distractions and placebos can all play a role in this pathway
the cingulate cortex, the insula and amygdala

Question 34

Hormones and anticonception

3

Answer 34

endorphins, epinephrine and norepinephrine

Question 35

Anterior pituitary purportedly releases ____

Answer 35

endorphins

Question 36

Adrenal medulla releases ____ that presynaptically inhibit the primary nociceptive afferent (just like the ceruleospinal tract of the descending pain pathways)

2

Answer 36

epinephrine and norepinephrine

Question 37

The non-nociceptive afferent fibers “close”, and nociceptive afferent fibers “open”, an imaginary “gate” to the transmission of nociceptive input to the brain

Answer 37

rub some dirt on it
gate control
tens