Chapter 14- Pain and Temperature Flashcards
What is pain?
Dysfunctions of general or specific senses that cannot be defined, identified or measured by an observer
What kind of phenomenon is pain?
Unpleasant but a protective phenomenon
Pain: Complex?
Interactions between physical, cognitive , emotional etc
How did McCaffrey define pain?
“Whatever the experiencing person says it is, existing whenever they say it does”.
What can pain and variations in temperature signal?
Disease
What is a common manifestation of temperature dysfunction?
Fever
What is often the first symptom of infectious or inflammatory conditions?
Temperature changes
What are the 3 Theories of Pain?
- Specificity theory
- Gate Control theory
- Neuromatrix theory
What is the specificity theory?
Injury activates specific pain receptors in the brain. Intensity of pain is directly related to associated tissue injury.
-Pricking one’s finger = minimal pain
-Cutting hand with a knife = more pain
What is the problem with the specificity theory?
Does not account for persistent, emotional 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 draw from various inputs (genetic, psychological, cognitive). However pain can be felt without them, like phantom limb. Therefore stimuli may trigger the patterns but do not produce them.
What are the 3 portions of the nervous system responsible for (in relation to pain)?
Pain perception, sensation and response
What are the 3 portions of the nervous system involved in perceiving pain?
- Afferent pathway
- Interpretive centres CNS
- Efferent pathways
What is Nociception?
processing of harmful (noxious) stimuli through nervous system
What are Nociceptors?
Pain receptors
What kind of nerve endings do Nociceptors have?
Free nerve endings in afferent PNS
What are the 2 types of nociceptors?
A delta fibers
C fibers
What are A delta fibres?
Large, myelinated that access large tracts in spinal cord
What are C fibers?
Smaller, unmyelinated that access smaller tracts in spinal cord
What pain is perceived by A delta fibres?
Fast sharp pain
What pain is perceived by C fibres?
Dull, throbbing pain
What kind of pain is perceived first? And what pain follows it?
Fast sharp pain is perceived first, followed by dull, throbbing pain
What is a transducer?
Device that converts variations into an electrical signal
What is Transduction?
Activation of nociceptors
What is Transmission?
Conduction to dorsal horn and up in spinal cord
What are the 3 systems of pain perception?
- Sensory-discriminative system
- Motivational-affective system
- Cognitive-evaluative system
What is the sensory-discriminative system?
Identifies presence, location and intensity (somatosensory cortex)
What is the Motivational-affective system?
Determines avoidance and emotional responses (reticular formation, limbic system)
What is the Cognitive-evaluative system?
Learned pain experience (can therefore modulate perception of pain)
What is pain perception?
Conscious awareness of pain
-Reticular and limbic system
What is Pain threshold?
Lowest intensity of pain that a person can recognise
What is Pain tolerance?
Highest intensity of pain a person can endure.
-Varies among people and in same person over time
How does pain tolerance decrease?
Decreases with repeated exposure
What is perceptual dominance?
Intense pain at one location may increase threshold (lower pain perception) in another location
What is pain modulation?
Different mechanisms act to increase or decrease pain transmission through nervous system
What peripheral triggering mechanism initiates excitatory neurotransmitters?
Tissue injury
Chronic inflammation
What are examples excitatory neurotransmitters?
Substance P
Glutamate
Histamine
Prostaglandins
What do excitatory neurotransmitters do to nociceptors?
Reduce nociceptors activation threshold, increasing the nociceptors’ responsiveness
What are examples of inhibitory neurotransmitters?
Opioids
GABA
Cannabinoids
Serotonin
Norepinephrine
What do inhibitory neurotransmitters do to pain?
Inhibit/reduce transmission of pain signal
What are endorphins?
Combination of “endogenous” and “morphine”
-Opiod neuropeptides
What is transmitted from the brain to inhibit pain signal?
Descending inhibitory impulse
What kind of receptors are Opiate receptors?
G protein coupled receptors
What do morphine-like neuropeptides bind with throughout the body?
Opiod receptors
What happens when opioid receptors bind with morphine-like neuropeptides?
Pain impulses in periphery, spinal cord and brain are inhibited
What are morphine-like neuropeptides responsible for?
Well-being
What does cannabis produce?
Resin containing cannabinoids
Cannabinoids are ________ in humans
Analgesic (relieve pain)