LECTURE 5- sensory receptors , pain science Flashcards
How many neurons pathways are there to the somatosensory cortex
3
what is the 1st order neuron
info from the sensory receptors to SC or BS
what is the 2nd order neuron
info betweeen SC or brain stem to thalamus
what is the 3rd order neuron
info from the thalamus to cerebral cortex
what is a receptor
converts stimulate energy into AP
what determines the type of receptors that are activated and pattern of signal transmission
stimulus
what is somatic senses
tactile, thermal pain , proprioception
what is visceral senses
conditions within internal organs
what are specialized senses
smell, taste, vision, hearing , balance and equilibrium
where are exteroceptor and what do they detect
at or near the body surface and detect external stimuli
where are interoceptors and what do they react to
deep and react to stimuli coming form internal body. organs (BH, blood pH)
examples of chemoreceptors
smell and taste
example of mechanoreceptors
touch
pressure
stretch
vitbratoin
what does each type of receptor have that are sensitive to stimuli that either damage or have potential to damage tissue
nociceptors
what are nociceptors
register pain
where are proprioceptors found
muscles , tendons , ligaments
what does tonic receptors detect and how do they adapt and how do they respond
detect object pressure and form
slow adapting
respond continuously as long as stimulus is present
what does phasic receptors adapt to , how do they adapt and what do they detect
adapte to continuous stimulus and then stop responding even if stimulus is present
fast adapting
detect motion, vibration , rate of change
what is the order of the peripheral sensory axons / afferents of decreasing diameter
la, lb, ll, lll, lV
where is there greater density of receptors
in distal body regions
what is considered to be superficial cutaneous receptors
meisners corpuscles (light touch , vibration)
merkel’s disk (pressure
what is in the subcutaneous cutaneous receptors
pacinian courpuscle
ruffinis ending
what are the 3 components of the sensory system
stimulus , receptors, conduction
what are the 4 attributes to condution
modality , location , intensity, duration
where are the 3 levels in the somatosensory system where signal processing for integration occur
receptor level
circuit level
perceptual leve
what is the speed of information processing determined by
axon diameter
amount of axon myelination
# of synapses in pathway
what is released when the AP goes above threshold
neurotransmitters
what circuit level processing is when synapses can spread action potentials to several areas of CNS
divergence
what is the convergence circuit level processing
synapses focus action potentials from several sensory neurons onto 1 narrowed area of CNS
what is perceptual level processing
sensory nerve tracts carry impulses to respective region of brain
What is a dermatome
skin area that is related to 1 spinal level
what is distal latency
time form stim to distal recording site
what is the pathology of peripheral nerve
neuropathy
what does nerve compression impact first and last
first - large myelinated axions and smaller nociceptive thermal and autonomic axons last
what can cause sensory ataxia
peripheral sensory nerves , dorsal roots, dorsal columns of SC or medial lemnisci
patients with _____ axatia will have similar motor performance eyes open/closed
cerebellar
what will be intact with cerebellar ataxia and impaired with sensory ataxia
proprioception/kinesthesia
what is a painful skin rash with blisters following a dermatome pattern
shingles/ herpes zoster
what is treatment for varicella zoster
antiviral drugs within 72 hours post onset
what are free nerve endings that respond to noxious stimuli
nociceptors
where are nociceptors located
skin, muscle joints
what is the malfunction of neural pain regulating processes causes pain without the presence of tissue injury
non- nociceptive pain
what central processing areas are active during perception of pain
cingulate and insular
enkephalins , dynorphin , and b- endorphins are examples of what
endorphins
what brain regions have opiate receptors that bind with both endorphins and opiates
rostral ventromedial medulla
periaquedcutal gray in midbrain
locus coeruleus in pons
what are the inhibitory neurons in the SC of endogenous opioids
enkephalin and dynorphin
what type of fibers are nocicpetive and non- nocicpetive
C and AB
what theory is the activation of non- nociceptive sensory neurons close a “gate” for central trasnmission of nociceptive signals
gate control theory
what does periphery pain inhibition do
decrease synthesis of prostaglandins
what does the dorsal horn release for pain inhibition
enkeohalin or dynorphin
what type of pain can MSK injury’s trigger
fast and slow pain
what is pain that is perceived as coming from site distinctly different from actual OG site
referred pain
referred pain is usually referred from _____ tissues to ___
visceral to skin
what is primary pain
neural dysfunction that creates pain without evidence of tissue damnage
• Fibromyalgia
• Complex regional pain syndrome
• Chronic nonspecific low back pain
migraine HA’s
are examples of
primary pain
what is secondary pain
initially a symptom of another medical condition
what is secondary pain caused by
- continuous stimulation for ncicopetors from tissue injury
- continued signaling after tissue has healed
- damage to somatosensory system
where does the central sensitization impact neurons?
through CNS
dorsal horn, BS , thalamus , cerebral cortex
what causes cellular changes including gene alterations and structural change in central sensitization
glutamate and neuropeptides
what is abnormal sensation that is painless with no nociceptors stimulation
parasthesia
what type of sensation do u get with parasthesia
tingling
what is pain that arises as a direct result of a lesion or disease that affects the somatosensory system
neuropathic pain
in neuropathic pain , central sensitization is characterized by
dysesthesias
what is dysesthesias
unpleasant sensation that can occur on its own or with stimulation
what does dysesthesias feel like
burning shooting or electrical sensation like hitting funny bone
what i so ain’t hat is caused by something that normally wouldn’t cause pain
allodynia
what are the 4 types of dysesthesias
allodynia
hyperalgesia
spontaneous pain
temporal summation
what is primary. hyperalgesia
stimuli that are normally mildly painful in injured tissue are causing excessive sensitivity
what is secondary hyperalgesia
pain spreads to uninjured areas close to injury site
what is pain unrealted to external stimulus
spontaneous pain
what is increased pain due to repeated stimulus or continued prescience of single stimulus
temporal summation
what disorder is it when people have tenderness and stiffness of muscle and neighboring tissues and achy pain
fibromyalgia
people with FM have sig less gray matter density where
medial frontal cortex, mid cingulate cortex, and insular cortex
is complex regional pina syndrome related to peripheral nerve or spinal never root distribution
none of
complex regional pain syndrome is regional typically worse in
unilateral distal limb
what is complex regional pain syndrome trigggerd by
abnormal response to trauma
what is early stage of complex regional pain syndrome
res or pale skin
a lot of sweating
edema
skin atrophy
Raised levels of neurochemicals that produce peripheral neurogenic inflammation is the pathology for what
complex regional pain syndrome
complex regional pain syndrome is central sensitization with structural and function changes of
• Thalamus
• Somatosensory cortex - reduction of hand or foot cortical maps
• Cingulate cortex
• Hippocampus
• Amygdala
what are locations that are outside of the nociceptor or soma that trigger action potentials
ectopic foci
what is also called cross talk
ephaptic transmission
what is lack of insulation due to demyelination allows an action potential in 1 neuron to cause an action potential in another neuron
ephaptic transmissions
small fiber neuropathy is seen in ppl with
post herpetic neuralgia
diabetic neuropathy
guillain barre syndrome
what pain is Caused by lesion to CNS, localized to area of body deafferented by the lesion
central pain
what is the great wall of fire
burning shooting aching freezing tingling pain
what pain is due to absence of sensory inputs causing neurons in central nociceptive pathways to be overly active
phantom limb pain
what are the “3 D’s” of chronic pain
distress
disuse
disability
what is the difference from phantom limb sensations and residual limb pain
phantom limb sensation is pain to limb that is not there anymore where as residual limb pain is pain where the amputation occurs
where does central pain come form post SC
coming from thalamus
where does central pain come form post stroke
thalamus affecting the contralateral body
where is the central pain for multiple sclerosis
the body part that is affected by the lesion location
