Perception of Pain Flashcards
What is pain
The unpleasant sensory and emotional experience associated with actual or potential damage
Do you need tissue damage to feel pain
No
In people who can’t feel pain what are blocked
Certain Na+ channels
What are factors that relate to the perception of pain (6)
- Sensory input from body
- Previous experiences
- Cultural factors
- Social/work environment
- Expectations about consequences
- Beliefs, knowledge, and logic
What is nociception
Encoding of noxious stimuli
What are the receptors that have a nociceptive function (4)
- Thermal nociceptors
- Mechanical nociceptors
- Polymodal nociceptors
- Silent nociceptors
What are thermal nociceptors
Activated by the extremes of temperature
What temperatures activate thermal nociceptors
Over 45 C and under 5 C
What are mechanical nociceptors
Activated by intense pressure or tension applied to the skin
What are polymodal nociceptors
Respond to a wide range of stimuli
What do polymodal receptors respond to (3)
- Thermal
- Mechanical
- Chemical
What are silent nociceptors
Truly silent until injury in viscera and in and around joints
When do silent nociceptors become activated
Only in the presence of inflammation
What are silent nociceptors activated by (2)
- Inflammation
2. Other chemical agents
How are transient receptor potential ion channels (TRPV1) expressed
Selectively by nociceptive neurons
What does TRPV1 mediate
Pain producing actions of capsaicin
True or False:
TRPV1 responds a lot to thermal stimuli
True
True or False:
TRPV1 is influenced by changes in pH
True
Where is capsaicin found
Peppers
Does TRPV mediate or modulate behavior and why
Modulate behavior because it is a second messenger
True or False:
Second messengers don’t stay local they affect other areas and go retrograde
True
What does bradykinin activate
A G-protein coupled BK receptor which activates PLC
What does the activation of PLC do
Leads to hydrolysis of PIP2
What does hydrolysis of PIP2 lead to
- Production of IP3 and the subsequent release of Ca++
2. Production of DAG and activation of PKC
What does PKC do
Regulates TRPV1 channel opening
What fiber sends sharp quick pain
A-delta fibers
What fiber sends dull slow pain
C fibers
Where does nociceptive stimuli synapse
On interneurons in the dorsal horn
Which lamina is thought to be all sensory
Lamina 1
What lamina are important for pain sensation (3)
1, 2, and 5
What lamina do A-beta fibers synapse on (1)
4
What lamina do A-delta fibers synapse on (3)
1, 2, and 5
What lamina do C fibers synapse on (2)
1 and 2
Where do interneurons in lamina 1 and 5 send projections to
The brain via the thalamus
What are lamina 3 and 4 important for
Deep touch
What does lamina 1 receive input from (2)
A-delta and C fibers
What does lamina 2 receive input from (2)
A-delta and C fibers
What does lamina 5 receive input from (3)
A-beta, A-delta, and C fibers
What is lamina 1 specific for
Nociception specific and wide range of neurons
What is another name for lamina 2
Substantia gelatinosa
True or False:
Lamina 2 is a dense region of local interneurons
True
True or False:
Lamina 5 receives a wider range of noxious stimuli
True
Where do nociceptive signals cross and where does it go
The same level it enters the and goes up to thalamus
What are the 3 pathways that conduct nociceptive signals
- Spinothalamic tract
- Spinoreticular tract
- Spinomesenphalic tract
What does the spinothalamic tract contain
Nociceptive specific thermosensitive and wide range dynamic neurons
What lamina does the spinothalamic tract receive input from (3)
Lamina 1, 2, and 5
What lamina does the spinoreticular tract receive input from (2)
Lamina 7 and 8
Where does the spinoreticular tract terminate
In the reticular formation and thalamus
What lamina does the spinomesenphalic tract receive input from (2)
Lamina 1 and 5
Where does the spinomesenphalic tract terminate (3)
- Mesencephalic reticular formation
- Periaqueductal gray
- Amygdala via parabrachial nucleus
What is the spinomesenphalic tract thought to be involved in
The sleep cycle/patterns
What tract is responsible for use experiencing fear at night
Spinomesenphalic tract
What are are the lateral nuclear groups that relay information to the cortex (3)
- Ventral posteromedial nucleus
- Ventral posterolateral nucleus
- Posterior nucleus
What are the medial nuclear groups that relay information to the cortex (2)
- Central lateral nucleus
2. Intralaminar complex
How is the amygdala involved in pain experience
Processing and memory of emotional reactions
How is the primary somatosensory cortex involved in pain experience
Somatic sensation and movement planning
How is the hippocampus involved in pain experience
Consolidation of information from short to long term memory
How is the anterior cingulate cortex involved in pain experience
Plays a role in a wide variety of autonomic functions and rational cognitive functions
How is the primary motor cortex involved in pain experience
Plan and execute movements
How is the hypothalamus and thalamus involved in pain experience
Autonomic nervous system (regulating body temp, hunger, and sleep)
How is the prefrontal cortex involved in pain experience
Planning motor behavior, moderating social behavior
How is the cerebellum involved in pain experience
Movement coordination
True or False:
Treating pain is difficult because it is not one sensory event
True
True or False:
Nociception is neither necessary nor sufficient to experience pain
True
You do not need nociception to have pain
True
True or False:
Pain is a conscious experience and requires cortical activity for the painful experience to exist
True
Can nociception occur without the presence of pain
Yes’m
Nociception is not synonymous with pain
Yes’m
True or False:
You need to generate an excitatory signal for pain to occur
True
What does the periaqueductal gray do to decrease the perception of pain
Releases a lot of endorphins
What happens if the postsynaptic cell is hyperpolarized
We do not get an AP
What does activation of nociceptors lead to
The release of glutamate producing an EPSP in the projection neuron
How do opioids effect the EPSP
They decrease the duration of the EPSP
What do opiods lead to (2)
- Decrease in Ca++ influx
2. Hyperpolarization of projection neuron via activation of K+ channels
True or False:
Depending how hyperpolarized the neuron is we may be able to block the signal
True
What is the pathway of nociception stimulation
Signal sent to special neurons synapse on dorsal horn cross over to the other side and go up to the brain then are sent to specific areas.
True or False:
Even though nociceptive signals are sent up to the brain doesn’t mean we will always experience pain
True
