Neuro and pain Flashcards
Purpose of PNS
Transmits any stimulus from the periphery towards the CNS
- afferent fibers
- composed of sensory and motor fibers
- 4 types of fibers: A-alpha, A-beta, A-delta, C fibers
Purpose of CNS
Integration and command center
- interprets incoming sensory information from the PNS and facilitates a response
- efferent fibers
Neuron
Nerve cell that conducts messages via nerve impulses betweeen the peripheral and central nervous systems
- compels of dendrites, cell body, and an axon
- communicate via action potential
Action potential
Basic unit of nerve communication
- Resting state: Na+ outside, K+ inside
- Depolarization: triggering response all or nothing response, not in relation to intensity of stimulus, it either happens or it doesn’t. Na+ moves into cell, propagates action potential
- Repolarization: returning to resting state. K+ moves in and Na+ back out
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Generation of action potential
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Determinants of nerve conduction
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Saltatory conduction
- literally means “jumping” of an action potential along the axon
- faster than transmitting down a continual sheath
Pathway of nerve transmission
PNS -> spinal cord -> brain
Pain
An unpleasant sensory and emotional experience associated with actual or potential tissue damage. Essential for survival - response to actual or perceived danger
- every person’s threshold (all or nothing) for pain is the same, however perception and tolerance vary based on personal experiences.
- surgery is controlled injury
- huge emotional component
Acute pain
Caused by actual or impending injury/damage
- usually associated with a known trauma/injury
- lasts as long as noxious stimuli is present and resolves once cause is removed
- responds well to treatment focused on early tissue healing and restoration to normal movement.
- no time frame, varies by normal time range for injury
Chronic pain
Pain that does not resolve in expected healing time or persists beyond duration of noxious stimulation
- cause is often not immediately identifiable
- pain may be persistent or recurring
- it has not usually responded to invasive medical interventions
- multi-factorial in nature, with associated loss in function
Referred pain
Pain arising from deep body structures felt at a location different from its source
- error in the localization of pain (need to read book for more information)
Nociceptive pain
Pain as a direct result of stimulation of pain receptors associated with ongoing tissue damage
Neuropathic pain
Pain as a result of a lesion or disease process affecting nerves
Dysfunctional pain
Pain that is persistent and does not provide a protective purpose, often associated with chronic pain
Psychogenic pain
Large psychological role with pain
Pain reception and transission
Nociceptors: Primary efferent pathway
- peripheral nerve endings located in most tissue types that respond to painful stimuli, mechanical, thermal, and chemical (C and A-delta fibers)
- quality of pain is dependent on type of nerve transmitting
- intensity of pain is dependent on firing rate of the nerves
C fibers
Small, unmyelinated
- sensitive to all noxious stimulus
- dull, throbbing, aching, burning, tingling, tapping sensations
- diffuse pain
- slow onset, long duration (1-4 m/sec)
- emotionally difficult for pt
How does pain get from PNS to CNS
- Carry pain sensation from the periphery to spinal cord
- Where pain modulation occurs. Transmission of pain either towards the cerebral cortex or elecitation of flexor withdrawal
- Where pain is interpreted, and sent to higher brain centers
- Conscious awareness of pain
Pain-spasm-pain cycle
Reflexive muscle spasm that occurs in response to a painful stimulus to “protect” the injured area.
- results in mechanical compression of nociceptors and an increase in chemical irritants resulting in pain followed by spasm
Not sure?
- Decreased circulation
- Decreased O2 supply
- Decrease lymphatic clearing
- Decreased nutrient supply
- Increased metabolism
- Increased concentration of metabolites
- Increased muscle fatigue
- Inflammmation and edema
Flexor withdrawal
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