Pain and Anagesia Flashcards
Define Pain.
Integration and processing of nociceptive input by the brain allowing it to be recognised as pain (cortical recoginition)
Define nociception.
Information regarding a noxious insult relayed from periphery to the CNS
Outline the three aspects of pain (S, M, C)
- Sensory - Recognition 2. Motivational - Affective 3. Cognitive - Evaluative (recognise consequences)
Name the different types of pain.
Phys/Path Somatic/ Visceral Acute/ Chronic
Describe the difference between somatic and visceral nociceptors.
S - numerous and widespread, small receptive fields, assoc with skin, muscle, bone & joints, respond to chemical, thermal and mechanical stimuli. V - sparsely distributed, large receptive fields, respond to ischemia, distenstion and inflammation, stimuli threshold depends on area affected rather than intensity.
Describe the difference between somatic and visceral pain.
S - localised to site of injury, sharp/ stabbing pain. V - Poorly localised and diffuse pain, autonomic associated, may be referred.
Functional/ anatomical adaptation of NS in response to environment/ physiological processes. What can be the consequences of this process?
Neuroplasticity - hyperalgesia, allodynia, chronic pain
Allodynia
Normally innocuous stimuli being percieved as painful
Hyperalgesia
Exaggerated response to normally painful stimuli
Define multimodal analgesia.
Formulation of an analgesic plan which affects multiple steps in the nociceptive pathway: transduction, transmission, modulation and perception
Describe the different stages of the nociceptive pathway.. (x4)
- Transduction - Applied stimuli converted into an electrical signal (AP) by activation of nerve end receptors
- Transmission - Conduction of impulses to and from the CNS (& of ascending and descending impulses within the CNS)
- Modulation - Alteration at the spinal cord level due to alteration of neuronal sensitivity and NT release
- Perception - CNS centres - RAS, thal/hypothal, cingulation gyrus, amygdala, hippocampus, cortex
Name and describe nociceptor receptors..
- Free nerve endings
- Higher activation thresholds than specialised receptors
- A delta and C fibres
- Prolonged stimution results in sensitisation
Which nociceptive have the highest activation thresholds?
A delta fibres < C fibres
Name substances which can cause activation of nociceptors.
- Cell damage products - prostaglandin E2, H+, K+, ATP, Leucotrienes
- Sensory nerve endins - substance P, CGRP
- Plasma, platelets and mast cells - hisamine, bradykinin and serotonin
What is peripheral sensitisation?
When inflammatory mediators and products of cell damage lower nociceptor threshold and recruit silent nociceptors.
Results in primary hyperalgesia, primary allodynia