Ch 14- Pain and Temperature Flashcards
what is pain?
dysfunctions of general or specific senses
what are some characteristics of pain?
- unpleasant but protective phenomenon
- cannot be defined, identified, or measured by an observer
- complex: interaction between physical, cognitive, and emotional
how is temperature like main?
variations in temperature can signal disease
- fever is a common manifestation of dysfunction
- often first symptom of infectious or inflammatory conditions
what is the specificity theory?
- injury activates specific pain receptors to brain
- intensity of pain is directly related to associated tissue injury
- problem: does not account for persistent, emotional pain
- pricking ones finger=minimal pain, cutting hand with knife= more pain
what is the gate control theory?
- combines and builds upon theories to explain multidimensional aspects of pain
- pain transmission is altered by a balance of signals sent to spinal cord where cells work as a “gate”
- spinal gate controls pain transmission to higher centres in CNS
what is the neuromatrix theory?
- brain produces patterns of nerve impulses drawn from various inputs including genetic, psychological and cognitive experiences
- pain can be felt without experiencing it, meaning stimuli may trigger the patterns but do not produce them
what are the 3 portions of the nervous system that are responsible for pain perception, sensation, and response?
- afferent pathway
- interpretive centers (CNS)
- efferent pathways
what does nociception mean?
processing of harmful (noxious) stimuli through nervous system
what are nociceptors?
pain receptors
- free nerve endings in afferent PNS
what are the 2 types of nociceptors?
- A-delta fibers: large, myelinated, and access large tracts in spinal cord
- C fibers: smaller, unmyelinated, and access smaller tracts in spinal cord
what is received first? A delta or C fibers?
fast sharp pain is perceived first (A delta fibers) followed by a dull, throbbing pain (C fibers)
what does transduction mean?
activation of nociceptors
what does transmission mean?
conduction to dorsal horn and up spinal cord
what does sensory-discriminative system identify?
presence, location, and intensity
what does the motivational-affective system determine?
avoidance and emotional responses
what does the cognitive-evaluative system do?
learned pain experience (can therefore modulate perception of pain)
what is a transducer?
device that converts variations into an electrical signal
what does pain perception mean?
conscious awareness of pain (reticular and limbic system)
what does pain threshold mean?
lowest intensity of pain that a person can recognize
what does pain tolerance mean?
- highest intensity of pain a person can endure
- varies greatly among people and in same person over time
what is perceptual dominance?
intense pain at 1 location may increase threshold (lower pain perception) in another location
what does pain modulation mean?
different mechanisms act to increase and decrease pain transmission through nervous system
what are excitatory neurotransmitters? (tell the brain there is pain)
- Substance P
- Glutamate
- Histamine
- Prostaglandins
- Reduce nociceptors activation threshold= increased responsiveness of nociceptors
what are inhibitory neurotransmitters?
- opioids
- GABA
- cannabinoids
- serotonin
- norepinephrine
- inhibit/reduce transmission of pain signal
what peripheral triggering mechanism initiate excitatory neurotransmitters?
tissue injury and chronic inflammation
what is the descending pathway and endorphin response?
descending inhibitory impulse transmitted from brain to inhibit pain signal
what are endorphins?
combination of endogenous and morphine
what are opiate receptors?
G protein coupled receptors for endorphins which are opioid neuropeptides
what do prphine-like neuropeptides bind with and what do they do?
they bind with opioid receptors throughout body to inhibit pain impulses in periphery, spinal cord, and brain
- responsible for sensations of well- being
what are cannabinoids?
- cannabis produces a resin containing cannabinoids
- analgesic (relieve pain) in humans
- drawbacks: psychoactive (affects the mind) and addictive properties
- 2020 legalized in Canada
what are endocannabinoids?
synthesized in body from phospholipids/ modulate pain and other functions
how does alcohol pain reduction work?
- functions by depressing central nervous system
- it slows down brain and nervous system/ delivers a certain amount of pain relief
what is the 1200-1500 England method of pain relief?
- potion called “dwale” used as an anesthetic
- alcohol-based, bile, opium, lettuce, hemlock (highly toxic plant), and vinegar
what was the 1840 pain method?
ether created
what are the 1846 pain method?
first pain-free surgery performed in amphitheater of massachusetts general hospital
what is acute pain (nociceptive pain)?
- protective mechanism that alerts to harmful condition and mobilizes person to relieve it
- pain lasting minutes to several weeks, you recover from it
what areas does acute pain arise from?
- Somatic:
- skin, joints, muscles, very localized
- sharp and well localized= A delta fibers
- dull throbbing= C fibers - Visceral:
- internal organs and lining of body cavities
- poorly localized, aching, throbbing quality to pain
- C fibers - Referred:
- felt distant from point of origin
- cutaneous (skin) and visceral receptors converge on same ascending neuron
- brain cannot distinguish between the 2 because skin has more receptors often is referred to a skin area
what is persistent pain (intractable pain)?
- pain that lasts more than 3-6 months (pain lasting well beyond expected healing time)
- serves no purpose/ poorly understood
- ongoing (back pain) or intermittent (migraine headache)
- studies: change in brain= reduced ability to cope with pain
what is neuropathic pain?
- cause: dysfunction of nervous system= long term changes in pain pathway and abnormal processing
- chronic/amplification of pain
- described as burning, shooting, shock-like, or tingling
- characterized by increased sensitivity to painful and non painful stimuli with hyperalgesia ( hyper=increased/algesia=capacity to feel pain)
what does analgesia mean?
absence of pain
what is pyrogen?
substance that produces fever when released into blood
what is a fever?
temporary resetting of hypothalamic thermostat to a higher levels in response to exogenous or endogenous pyrogens
what cause the release of endogenous pyrogenes? (TNF-a, IL-1, IL-6) ?
exogenous pyrogens (pathogens)
what do pyrogens do?
raise thermal set point by inducing hypothalamic synthesis of prostaglandin E2 (PGE2)
what is the prostaglandins effect?
increase temperature through increased heat production and conservation
what happens during the prostaglandins effect takes place?
the individual feels colder, curls up to decrease body surface area, goes to bed to get warm
- cause: heat conservation through cutaneous vasoconstriction
when does increased body temperature come back down?
when fever breaks and original set point is reinstated
- individual feels warm, throws off covers, and stretches out
what are the benefits of a fever?
- kills microorganisms affecting their growth and replication
- decreases serum levels of minerals needed for bacterial replication in infected cells
- causes lysosomal breakdown, preventing viral replication in infected cells
- hat facilitates immune response
- phagocytosis enhaced and antiviral interferon is augmented
- suppression of fever can be effective but should be used with caution
what are heat cramps?
- severe spasmodic cramps in abdomen and extremities
- follows prolonged sweating and associated sodium loss (40-60 mmol of sweat)
- common in individuals not accustomed to heat or performing strenuous work in warm climates
- si/sy: increased core temp, rapid pulse, and increased blood pressure
what is hyperthermia?
- elevation of body temperature without an increase in hypothalamic set point
- can produce nerve damage, coagulation of cell proteins and death
what is heat exhaustion?
- result of prolonged high core or environmental temperatures
- profound vasodilation and profuse sweating= dehydration, hypotension, tachycardia
- manifestations: dizziness, weakness, nausea, confusion
what is a heat stroke?
- potentially lethal
- 41 C (nerve damage, convulsions)
- 43 C (death)
what is hypothermia?
- normal: 37 C
- hypothermia: less than 35 C
- produces ice crystals inside cells= cellular rupture
what is tissue hypothermia?
- slows cellular metabolism rate
- increases blood viscosity
- facilitates blood coagulation and vasocontriction
what is therapeutic hypothermia?
- used to slow metabolism= preserve ischemic tissue during surgery
- risk: may lead to ventricular fibrillation and cardiac arrest
