Lecture 14: 9/30 - Pain Flashcards
Test 2
What pathway does fast pain go up?
Lateral spinothalamic tract
What pathway does slow pain go up?
Anterior spinothalamic tract
Where are the fast pain synapse?
Laminae I
What type of fibers do fast pain travel on?
Heavily mylinated A-Delta fibers
What is a pain neuron called?
Nociceptor
Free nerve ending
What are the neurotransmitters on for fast pain?
Glutamate
Where is fast pain sent to?
Parietal Lobe (post central gyrus)
What pathway slightly mimics the fast pain pathway?
DCML
Describe Glutamate in fast pain
Fast to release and bind to receptor
Fast to generate AP
If there is fast pain on your LE, what part of the parietal lobe is that sent to?
Midline/Top
If there is fast pain on your face, what part of the parietal lobe is that sent to?
Lateral
Why can you localize fast pain better than slow pain?
Fast pain mimic the DCML and terminates in the parietal lobe vs slow pain that does always reach that far. The parietal lobe controls your senses
What are the neurotrasmitters in slow pain?
What is the main one?
Glutamate
Substance P
Calcitonin Gene-related peptide (CGRP)
Substance P
Where are the synapse for slow pain?
Laminae II, III, and V
Describe Glutamate in slow pain vs fast
Glutamate acts slower in slow pain
What is a Neospinothalamic tract?
New pain pathway that has branched off of slow pain pathway. More sophitocated
What is a paleospinothalamic tract?
older tract that hasnt been developed much
T/F: Slow pain transmitters are slow to release and bind to receptor and generate an AP
T
Where does crossover happen in pain?
Anterior White Commisure (AWC)
T/F: Pain goes up the spinal cord on the same side the pain went into the spinal cord
F
Pain crosses over at the AWC before going up
Describe the pathway of fast pain
Dorsal root/rootlets -> Dorsal horn -> Laminae 1 (Laminae marginalis) -> Crossover at AWC -> Lateral spinothalamic tract -> ascends through the spinomesencephalic tract -> thalamus -> ventrobasal and intralaminar nuclei of the thalamus -> internal capsule -> Parietal lobe / cortex
Where are the somatosensory areas?
Parietal lobe
What areas do the DCML and fast pain have in common?
Ventrobasal complex in the thalamus and the internal capsule
Where do slow pain signals normally terminate?
Where is this?
Reticular formation
Tissue at the top of the brainstem
If slow pain does go pass the reticular formation, where does the signaling usually go?
Limbic system
Describe extrapyramidal tract: Olivospinal
Descending motor pathway
only needs to know it exists
Describe extrapyramidal tract: Vestibulospinal
Descending motor pathway
Balance; focuses eyes when body is moving
Describe extrapyramidal tract: Reticulospinal
Maintains muscle tone
Describe extrapyramidal tract: Rubrospinal
Monitors involuntary movements from the brain
DIC =
Descending Inhibitory Complex
T/F: DIC can completely suppress pain
T
DOES NOT USUALLY DO THIS but it can
What activates the DIC pain suppression system?
Pain
What receptors do opiods act on?
Enkephalin receptors
In the DIC: where are the initial neurons located?
The periaqueductal gray (superior to the 4th ventricle)
or
The periventricular nuclei (anterior to 3rd ventricle)
In the DIC: what does the 1st order neuron release?
Where is this released?
Enkephalin
On the 2nd order cell body (Serotenergic neuron) locate at the Nucleus raphe
In the DIC: where is the synapse for the 1st and 2nd order neuron?
Nucleus raphe in the center of the pons
In the DIC: what is the 2nd order neuron?
Serotonin neuron
What is Serotonin called?
5-HT
In the DIC: what is the 3rd order neuron?
Is it excitatory or inhibitory?
What does it do?
Enkephalin neuron
Inhibitory
Releases enkephalin on the synapse/laminae in the grey matter where pain is before crossover
Deep brain stimulation of the periventicular nuclei and periaqueductal gray does what?
activate DIC pathway
decrease pain…
What are things that can be perceived as pain?
Damage to the receptor
Increase in H+
Increase in lactic acid (ex. exercise)
Increase in K+ (think about dialysis pts)
Histamine (ex. mosquito bites)
5-HT in periphery
Ach in periphery
PGs in periphery
Bradykinin
T/F: taking antidepressants will increase pain
F
They help pain by increase the bioavailability of serotonin in the cord
What are antidepressants that can help with chronic pain?
SSRIs
Tricyclic antidepressants
What neuron runs parallel to pain neuron?
pressure neurons
What is lateral inhibition?
Pressure sesnor inhibiting pain senses
What is a negative SE associated with tricyclic antidepressants?
Drowsy
But will give them if depressed, with chronic pain, and cant sleep…
negative side effects are not helping
How does accupuncture works?
Lateral inhibition
What type of receptor is an opiate receptor?
What type of ion channel is it linked to?
GPCR
K+ ion channel
Volatile anesthetics increase ____ conductance
K+
T/F: Cox 2 decreases pain
F
COX2 increases PG which increase pain sensitivity
What is an AMPA receptor linked to?
Na+ ion channel
What is an NDMA receptor linked to?
Primarily Ca++ ion channel
Na+ gets through here as well
What are the differences between the AMPA and the NDMA receptors?
NDMA receptor is much slower to open/react after AP
NDMA receptor also needs to be depolarized FIRST
What ion blocks the NDMA receptor?
How do we unblock it?
Magnesium
Depolarizing the cell and Glutamate binding to the receptor
What happens to our NDMA receptors after we are born?
We develop more
What happens when we block the NDMA receptors? What can block them?
Decrease pain
Ethanol
Lead
Ketamine
Magnesium
Nitrous
Tramodol
What happens to the AMPA and NDMA receptors when we have chronic pain?
More AMPA and NDMA receptors appear at the synapse
What are the 3 glutamate receptors?
What type of receptors are these?
AMPA
NDMA
Kanate
Ionotropic
Where are metabotropic glutamate receptors found?
In the brain
What is a SE of taking alot of magnesium for pain?
GI disturbances - pooping
Which is better for pain; Ca++ or Mg++?
Mg++
What type of fiber for slow pain travel on?
Non-myelinated C-fibers
T/F: None of the slow pain signals make it to the parietal lobe
F
Some do; but most dont. Most terminate in the reticular formation. some make it to the limbiic system. some make it to the parietal lobe
How does COX2 contribute to pain?
Increased pain activates the release of COX2
COX2 increases PG which increase pain sensitivity
What is iNOS? What does it do?
Induceable form of NOS (nitric oxide synthase)
Increases pain signaling/sensitivity
What does Alpha 2 agonist do in the CNS?
Suppress pain and increase relaxation
help increase K+ permeability
What are some examples of Alpha-2 agonists?
Xylazen (horse tranquilizer)
Precedex (most specific)
Clonidine
