Nociception Flashcards
Nociceptors exist as free nerve endings activated only when the stimulus is ___.
strong enough to cause damage.
___ nociceptors have fast responses
thermal/mechanical
___ nociceptors are myelinated
thermal/mechanical
___ nociceptors are unmeylinated
polymodal
thermal/mechanical noiceptors are assocaited with ___ pain
sharp, prickling pain
polymodal nociceptors are assocaited with
with high intensity mechanical, chemical, hot, and cold stimuli.
Nociceptive specific neurons are found in___of the spinal cord
Lamina 1
nocipceptive specific neurons have ___ receptor fields
small
nocieptive specific neurons carry
only info about noceipcetion
. Wide dynamic range neurons (WDR) are found in ___ of the spinal cord
Lamina 5
Wide dynamic range neurons carry information
from both mechanoreceptors and noiceptors
Wide dynamic range neurons have ___ receptor fields
larger
. hyperalgesia is what happens when you have increased sensitivity to the ____.
surrounding unharmed region of a damaged area
with hyperalgesia Subsequent stimuli result in the
enhanced sensation of pain
referred pain is the result of a ____
lack of nociceptive output neurons in the dorsal horn that are dedicated to visceral pain
dissociated sensory loss is when you have reduced sensation of epicritic sensation in the opposite side of the body from where you have ___.
reduced sensation of temperature and pain
Pain modulation can occur as the result of the descending pathway synapsing with
an opiate containing interneuron
The opiate containing interneruon synapses with the ascending pathway in the dorsal horn releasing enkephalin that dampens
both presynaptic and postsynaptic neurons
pain vs. noiception?
pain is a psychological perception
where are the cell bodies of noiceptors?
located in the dorsal root and trigeminal ganglia.
Nociceptors exist as free nerve endings that do not have ___
peripheral structures
____ nociceptors have small-diameter, thinly myelinated A
thermal/mechanical
___ noiceptors have small- diameter, unmyelinated C fibers
polymodal
If the stimulus intensity is raised to a level that activates A
tingling sensation
If the stimulus intensity is raised to a level that activates A
sharp pain
If the stimulus intensity is increased further, so that the small-diameter, slowly conducting C fiber axons then a a ___ is experienced.
duller, longer-lasting sensation of pain
The vanilloid receptor TrpV1 is found in both___ fibers
C and A
TRPv1 is Activated by stimuli such as (3)
capsaicin, heat, acids and anandamide
___ receptors may respond to endogenous chemicals similar to capsaicin that are released with peripheral injury
TrpV1
in the flare region following hyperalgesia, ___ drops dramatically
threshold sensitivity
The release of ___ ___ and ___ , and other agents from the site of injury enhances the responsiveness of nociceptive endings
bradykinin, histamine, prostaglandins
*these make protect yoiu from contuoally hurting yourself
Electrical activity in the nociceptors also stimulates the local release of chemical substances (such as substance P) that cause __, ___, and ___
vasodilation, swelling, and the release of histamine from mast cells.
aspirin and other NSAIDS act by inhibiting cyclooxygenase, an enzyme important in the biosynthesis of ___
prostaglandins
Local pain can be sensed even when nociceptive pathways are damaged bc
pain can arise spontaneously in the
absence of activity in nociceptors.
branches of A and C noceiptive fibers descend for a few segments as part of the ___ when they enter the spinal cord
dorsolateral tract
Nociceptive fibers terminate primarily in the ___
superficial dorsal horn (lamina 1 and 2)
Few if any neurons in the dorsal horn are specific to conveying ___ pain
visceral
Referred pain is the displacement of pain from a visceral structure such as to a somatic area of the body because of the convergence of visceral and cutaneous nociceptors onto the same ____ projection neurons
dorsal horn
ureteral pain (like in passing a kidney stone) referred to ___ and ___
lower abdomen and back
bladder pain referred to the ___
perineum
Prostate pain with a characteristic distribution
above and below the effected side
Axons from the from ganglia associated with nerves ___ carry information from facial nociceptors and thermoreceptors
5, 7, 9, 10
The major target nuclei of the ascending pain and temperature axons are the ___ of the thalamus
vpl and vpm
Somatosensory cortex receives nociceptive information from ____ of the thalamus.
VPN
how are nocipceptive inpurs organized in the cortex?
No orderly arrangement
Neurons in the ___ make inhibitory connections in laminae I, II, and V of the dorsal horn (these laminae are also the site of termination of nociceptive afferent neurons)
rostroventral medulla
Electrical stimulation of___ or ___results in the inhibition of dorsal horn neurons that respond to noxious stimulation.
periaquedcutal gray or rostroventral medulla
Electrical stimulation in either the PAG or rostroventral medulla results in the inhibition of dorsal horn neurons that respond to noxious stimulation.
this effect cna be eliminated with X of the
dorsolateral funiculus (which is carrying this descending information)
Administration of low doses of opiates directly into __ and ___ produce analgesia
PAG and rostroventral medulla
The descending inhibition of spinothalamic tract neurons appears to be mediated by the activation of ____ interneurons in the dorsal horn.
enkephalin
The descending axons of serotonergic and noradrenergic neurons from the nucleus raphe contact (2)
- dendrites of ALS neurons
- inhbiitory neurons in superficial dorsal horn
The ___ contains a high density of enkephalin- and dynorphin-containing interneurons
superficial dorsal horn
opiates and opioid peptides regulate nociceptive transmission by releasing
glutamate, substance P, and other transmitters
Neurons in the periaqueductal gray matter make excitatory connections in
the___
rostroventral medulla
Opiate receptors are located both on the
terminals of nociceptive afferents
and on the dendrites of postsynaptic neurons.
Opiates also act postsynaptically at afferent synapses to suppress the
activity of ___
nociceptive dorsal horn neurons.
