Lecture 5 PT 1 Flashcards
Where are 1st order neurons found?
Between sensory receptor and spinalcord/brainstem
Where are 2nd order neurons found
Between Spinalcord and brainstem/thalamus
Where are 3rd order neurons found?
Between thalamus to cerebral cortex
Conduction vs translation
Conduction - impulse over pathway to CNS
Translation- CNS receives impulse and integrates info (may prepare response)
Somatic/visceral/pain/tactile/proprioceptive senses are handled by what kind of receptors?
General receptors
What kind of receptors handle Smell, Taste, vision, hearing/balance
specialized
Hair cells are found on ________ receptors
specialized
__________ determines the types of receptors that are activated
The stimulation (what kind it is)
Exteroceptor vs Interoceptor
Exteroceptor- Detect external stimuli
Interoceptor- Stimuli coming from inside body
Each type of receptor has a subset of _______ that are sensitive to simuli that either damage or have potential to damage
Nocioceptors
Where are proprioceptors found?
Found in muscles, tendons, ligaments
What receptor is described as:
Responds continiously as long as stimulus present
slow adapting
Detects pressure and form of objects
Tonic receptor
What receptor is described as:
Adapts to continuous stimulus and stops responding to stimulus
-Fast adapting
-detects motion, vibration, rate of change
Phasic receptor
sensory receptors with a smaller field are _______ sensitive than one with a larger field
more sensitive (can tell the difference between 1 and 2 points of contact that are close together)
Larger receptive field are generally found _____
More proximally
Smaller receptive fields are usually found…
distally
Greater density of receptors is found ______ in the body
Distally
What kind of cutaneous receptors are small field receptors?
Meisners corpuscles (light touch)
Merkel’s disks (pressure
How I will remember: M&Ms are small field receptors. Because both small field receptors start with an M
What are the two kinds of subcutaneous receptors
Pacinian corpuscle - touch vibration
And Ruffini’s endings- stretch of the skin
Superficial receptors typically have a _____ receptive field whereas subcutaneous fibers have a _____ receptive field
Superficial: small
Subcutaneous: Large receptive field
Mechanoreceptors/Aβ fibers handle what sensations?
Light touch- vibration, stretch, skin pressure
Free nerve endings AKA Aδ Fibers handle what sensations?
Course touch (pleasant touch/pressure/tickle/itch)
Pain
And Temperature (thermoreceptors)
The symbol is a delta symbol, how i will remember this: riding on delta airlines is very painful, hot, and the seats are course (maybe she meant coarse? Idk the slide said course) to the touch
True or false: naturally stimuli will only activate one type of receptor
False
What are the 4 attributes of conduction?
Modality
Location
Intensity
Duration
A stimulus with a larger duration or larger amplitude will lead to…
More neurotransmitter release
Signal processing for integration occurs at what 3 levels of the somatosensory system?
Receptor Level
Circuit Level
Perceptual level
The speed of information processing is determined by what 3 factors
Axon diameter
Myelination
Number of synapses in pathway
Divergence vs Convergence
Divergence- Synapse spreads action potential to several areas of CNS
Convergence - Synapses focus action potentials from several sensory neurons into narrow area of CNS
How are peripheral and Spinal dermatomes different in the extremities vs the trunk
The lumbosacral plexus and brachial plexus allow for mixing of spinal roots to where periphrial nerves receive multiple spinal levels, this mixing is not present in the trunk
What are 3 challenges to testing for sensory deficits
Patient alertness/cognition
Cheating
Equipment availability
Nerve conduction velocity testing
Compare electrical stimulation to peripheral nerve and compare with norms
Distance latency - Time from stim to distal recording site
Amplitude- # axons conducting
Conduction velocity- testing for Myelination
True or false: a nerve conduction velocity test is typically done at the same time as EMG
True
What is a SSEP (somatosensory evoked potentials) test
Tests peripheral and central pathways, the conduction is measured proximally and at the cerebral cortex
What is the order of sensory loss (note: sensory returns in reverse order)
- Conscious proprioception/ light touch
- Cold
- Fast/sharp stinging pain
- Heat
- Slow aching pain
Nerve compression impacts large myelinated axons first and _______ last
Smaller nocioceptive thermal and autonomic axons last
What is sensory Ataxia?
Loss of somatosensory , can be caused by Injury to peripheral nerves, dorsal roots, dorsal columns of SC, or medial lemnisci
What is the difference between peripheral ataxia and cerebellar ataxia?
Difference in eye open/eye closed testing.
Patients w/ cerebellar ataxia will preform the same with eyes open and closed
Proprioception is intact with cerebellar ataxia and absent with sensory ataxia
What is Shingles/Herpes zoster and how is it treated
Varicella Zoster virus infects dorsal root ganglion and appears as painful rash along dermatome
Treatment: antiviral within 72 hours
Prevention: vaccine for people over 50
Nocioceptive pain vs non-nocioceptive pain
Nocioceptive: Acute/chronic tissue injury
Non-nocioceptive: malfunction of neural pain regulating process WITHOUT presence of tissue injury
What kind of pain describes neuropathic, central sensitivity syndromes, or pain syndromes
Non-nocioceptive pain
Nocioceptors are free nerve endings that carry fast and slow pain by __________ (small fibers) to spinal cord
Aδ or C fibers (small fibers)
Pain experience is strongly linked to _______, ______, and cognitive phenomena
Emotional, behavioral
What areas of the brain are activated during central processing of pain?
Cingulate and insular areas
What are the two kinds of inhibitory neurons in the spinal cord for pain?
Enkephalin and Dynorphin
Where are the 3 areas where the brain has opiate receptors to bind with endorphins
Rostral ventromedial medulla (raphespinal tract)
Periaqueductal gray in midbrain
Locus Coeruleus in pons (Ceruleospinal tract)
What are the 3 kinds of endorphins for inhibits pain signals?
Enkephalins , dynorphins, and B- endorphins
What is gate control theory?
Activation of non-nocioceptive sensory neurons can close “gate” for central transmitting of nocioceptive signal (pain)
Note: demonstrates that pain perception is regulated by balance of activity in nocioceptive and non-nocioceptive afferent fibers
How does the periphery of the nervous system inhibit pain?
Decrease synthesis of prostaglandins
How does the dorsal horn help with inhibiting pain?
Release enkephalin and dynorphin.
(endogenous opioids)
Nocioceptors that are excessively reactive to stimuli demonstrate ________ __________
Peripheral sensitization
Sensitized neurons can fire in response to normal stimuli and make it feel painful
______ pain usually occurs after a tissue has been damaged
Deep pain
True or false: Musculoskeletal injuries can trigger both fast and slow pain
True
What is the explanation for referred pain?
pain that is perceived as coming from site distincly different from actual origin site
Fibromyalgia, complex regional pain syndrome, chronic nonspecific LBP, and Migraines are example of….
Chronic pain as a disease/ primary pain
No evidence of actual tissue damage
What is larger, a 1a axon or a IV axon?
1a axon is larger than a IV axon
