Acute Pain Flashcards
What happens when a stimuli causes tissue damage
Nociceptors become activated
What’s the first thing Ab fibers do
They’re the first to recognise and localise the pain
Are ab fibers myelinated
Yes
What is does myelinated mean
The nerve is coated with myelin sheath
What kind of stimuli activate AB fibers
Mechanical and thermal
What speed are C fibres and are they myelinated
Slow and not myelinated
What stimuli activates C fibers
Chemical
Are AB fibers involved with modulation of pain
Yes
What nervous system do the pain signal get sent to
The spinal cord
Where do pain signals have to go through to get to the correct nervous system
Through the spinal ganglion
What is the simplified version of the pain pathway
- Periphery gets disrupted by stimulus
- Gets sent through spinal cord to posterior horn or anterolateral system
- Then gets sent to the cortex
What fibers contribute to the modulation of pain
Ab
Where do sensory afferents synapse
In specific laminae of grey matter in the posterior horn of the spinal cord
What are the different laminae where sensory afferents synapse
I,II,V
What do Wide Dynamic Range neurons do
They receive dynamic input from all types of sensory fibers
What kind of information do wide dynamic range neurons encode
They can encode a wide range of painful and non-painful stimuli
Where is inflammatory soup activated
In the periphery
What fiber does inflammatory soup activate
Fibre C, because it’s caused by a chemical reaction
What is inside of a inflammatory soup
Mast cells, Substance P CGRP, neuropeptides, serotonin prostaglandins, potassium, histamine, Bradykinin
What happens when a inflammatory is soup produced
Vasodilation, swelling, increase in white blood cells
Where do nociceptors and wide dynamic range neurons cross over when ascending to the anterolateral system
In the anterior white commissure of the spinal cord
Where does the Spinothalamic tract carry fibres to
thalamus then sent to the cortical pain matrix
What does the spinothalamic tract allow
It allows for the conscious experience of pain
Where does the Spinohypothalamic tract take fibers
They are projected into the hypothalamus
When the spinohypothalamic tract projects the fibers to the correct place, what happens
It creates the response to pain, e.g. increase in Heart rate, nausea
Where does the Spinomesencephalic send fibers
To the periaqueductal gray in the midbrain
What happens when the spinomesencephalic tract realised the fibers into the correct area
Downstream influences other brain systems that modulate pain
Where does the Spinoreticular tact send fibers
To the brainstem nuclei of the reticular formation including: Serotonergic Rahpe nuclei & Noradrenergic locus ceruleus
What is the job of the spinoreticular tract
Modulating pain
What are the 4 tracts that branch off of the anterolateral system
Spinothalamic tract, spinohypthalamic tract, spinomescencephalic tract, spinorecticular tract
Why do some fibers branch off through your the brainstem in the anterolateral system
To modulate pain
What are the 2 pain systems in the cortical regions
Lateral pain system, medial pain system
What areas of the brain does the lateral pain system use
Thalamus, somatosensory cortex, posterior parietal, somatosensory area (secondary somatosensory area)
What parts of the brain does the medial pain system use
Hypothalamus, amygdala, prefrontal cortex, hippocampus, anterior cingulate cortex
What does the medial pain system produce
The suffering of pain, “ouch”
Where in the pain pathway does all modulating signals relay back to
The posterior horn of the spinal cord
What are the 3 major mechanisms for pain modulation
Gate control theory, descending pathways, endogenous opioid system
What happens in the gate theory
When a painful area is rubbed, AB fibres are released to the dorsal horn, preventing the correct pain fibre to get there, reducing the pain
What are the 4 descending pathways
Cortical pain matrix, periaqueductal gray, locus ceruleus, raphe nuclei
What happens in the cortical pain matrix
Where the feeling of pain occurs, creates the response to pain
What is the periaqueductal gray
controls descending fiber projections to the raphe nuclei
What is the locus ceruleus and what does it contain
It contains norepinephrine neurons and modulates incoming pain, can fluctuate in usage
What does the raphe nuclei contain and what is it for
It contains serotonin and it’s job is to realise it into the brain and modulates pain
What are enkephalins
It is realised by the raphe nuclei and it inhibits the pain sensation
What is the endogenous opioid system
It is a pain relieving system
Where are opioid receptors found
The pain matrix, descending pathways, posterior horn of the spinal cord and peripheral nerves
What are opioid receptors and what do they do
They’re pain killers and they Stops pain
What effect do opioid receptors have on a presynaptic neuron
They close Calcium channels and open potassium channels
Within the neuron, reducing pain transmission neurons and realise good neurotransmitters
