Day 2 lecture: Pain Flashcards
The spinothalamic tract also sends collaterals to ____ (3)
- Reticular formation 2. Hypothalamus 3. Other Limbic structures (emotions) (associated more with c fibers)
True or False: Area of referred pain is supplied by the SAME spinal segment as actual site of pain.
True
Where can you find the cell body of the first order neuron?
Dorsal Root ganglia
FYI: A primary order neuron is a nerve and is part of the PNS. 2nd and 3rd order neurons are NEVER part of the nerve. (CNS)
So, in the test, he will name some crazy nerve name and will ask what kind of neuron it is. Answer is: Primary order neuron.
What lamina is involved in both WDR and NS
Lamina 1,2,5
Name 7 chemicals released by tissues that stimulate nocireceptors. (Pain mediators)
Bradykinin Serotonin K ions Prostaglandin (PGE-2, PGI-2) Substance P Histamine ACh
Pain Pathway Propagation of impulses along spinothalamic pathway then relayed by thalamus to the primary sensory cortex.
Transmission
Layers within the dorsal horn.
Lamina
Which lamina do C-fibers synapse with the second order neurons?
Lamina 1,2
True or False: Opioid analgesic and stimulation produced analgesia are produced via the same descending inhibitory system.
TRUE
These (3) substances are thought to be involved in endogenous analgesic pathway.
Norepinephrine, serotonin, opioids
Type of Pain: Pain is experienced at a point distant to its point of origin.
Referred pain
PAG receives impulses from many brain regions including ____ (3).
- hypothalamus 2. Thalamus 3. Cortex
The gate control theory is based on ______ of pain information produced by mechanical stimulation, and provides the basic rationale for the TENS.
presynaptic inhibition
Conduction speed of C Fibers
0.5 - 2 meters /sec (Slow and second pain)
Transduction is accomplished by what neuron?
First order neuron
Axons from the rap he nuclei, locus coeruleus and VTA project to the spinal cord dorsal horn by way of the ____ to terminate in Lamina 1,2,4,7.
dorsal longitudinal fasciculus. (DLF)
Pain Pathway: Affective/ motivational aspect.
Perception
Nociceptors are terminal endings of ______.
primary afferent fibers.
Neurotransmitters released by A-delta and C fibers are ____ (3)
Calcitonin gene-related peptide Glutamate Substance P
Opioid peptides acts on the presynaptic terminals of nociceptor fibers to prevent the release of ____ (2)
Substance P and glutamate
Starting point of descending inhibitory pathway
PAG in the caudal midbrain (PAG –> NRM –> spinal cord level)
True or False: The axon terminus of Secondary Neuron contains opioid receptors.
true
Area stimulated to produce SPA (stimulation produced analgesia)
- PAG: Periaqueductal gray 2. NRM: Nucleus Raphe Magnus 3. CN: Caudate Nucleus 4. SN: Septal Nucleus
Type of nocireceptor: Responds to more than one type of stimulus.
Polymodal
What substance (Opiate antagonist) blocks the effects of endorphin/ enkephalins?
Naloxone
Pain receptors
Nociceptors (Noci = harmful)
2 theories on Modulation of Pain
- Gate Control theory 2. Endogenous analgesic pathway
Type of Pain: Pain result from direct injury to nerves in the PERIPHERAL NERVOUS SYSTEM.
Neuropathic pain.
Difference between A-Delta Fibers and C- fibers
refer to slide 8
It forms the spinothalamic tract.
axons from the large cells
3 Primary afferent fibers (1st order neurons)
A-Delta and C fibers: for pain A-Beta: for general sensation
What type of cells are found in Lamina II
Both inhibitory and excitatory cells
The electrical stimulation of PAG and NRM inhibits _______ in laminae ____ (3).
spinal thalamic cells (2nd order neurons)…. laminae 1,2,5
The route from the PAG to the spinal cord is not direct. It appears to involve a link with ____ (3).
- 5HT-rich rap he nuclei 2. Norepinephrine from locus coeruleus (LC) 3. Dopamine from the ventral tegmental area (VTA)
Nociceptors can be classes into (2) ___. They are the two pain primary afferent neurons
- Myelinated A-Delta 2. Unmyelinated C fibers
It will release inhibitory neurotransmitters that will hyperpolarize the axon terminals. Therefore makes it less able to release neurotransmitters into the synapse. It will make it harder for action potential to occur in the secondary neuron.
Inhibitory interneuron at Lamina 1.
These are collection of cell bodies in the PNS
Ganglia
What lamina is involved with Low threshold stimuli?
Lamina 3,4
Type of Pain: Sudden onset, temporary (disappears once stimulus is removed), may be associated with ANXIETY.
Acute pain
Type of Pain: Stimulation pof receptors in internal organs, abd and skeleton. It is often poorly localized; it can be referred pain.
Visceral pain.
This theory states that non-painful afferent impulses entering the cord inhibit painful input (ascending pathway). Touch receptors vs pain receptors.
Gate control theory
These interneurons can exert an inhibitory effect on synapses between primary and secondary neurons.
Interneurons in the substantia gelatinosa