Analgesia Flashcards
What is pain
Unpleasant sensory and emotional experience associated with actual or potential tissue damage
How is pain sensed
Detected by primary sensory neurons - relays info to DRG - this benign info is relayed to the CNS
Whats the difference between pain and nociception
Nociception stops when stimulus is delivered to the CNS whereas pain causes an emotional response
How do nociceptors convey info from the periphery to the spinal cord
Transduction - physical change of stimuli from its original modality to an action potential (Na influx)
Conduction - initiated by Nav channels
Transmission - Neurotransmitter release from the neurons to second order ones (increased Cai)
What are the role of NSAIDs in analgesia
Aspirin, ibuprofen - inhibit COX enzymes that would normally produce prostaglandin E
What are the risks of NSAIDs
CV risk - increase risk of CV thrombotic events/stroke - no vasodilation
Gastrointestinal risk - Prostaglandins required in immune response in GI tract - Increase risk of bleeding, ulceration - especially seen in the elderly
What effects do opiates have on the body
Depression of respiration
Inhibition of peristalsis in the GI tract
Sedation - cognitive impairment
What is an example of a natural opioid
Morphine
What is an example of a semi-synthetic opioid
Heroin
What is an example of a fully synthetic opioid
Fentanyl
What is an example of an endogenous opioid peptide
Endorphins
What physiological response does morphine cause
Binds to opioid receptors (GPCRs) that lead to the inhibition of Ca channels and their influx - therefore neurotransmission is inhibited
What are the three types of opioid receptor
u - concentrated in the dorsal horn area and receive input from DRG neurons
k and delta
Where are endogenous opioids found
CNS, areas associated with brain processing
Released during stress and prolonged physical exercise
How are endogenous opioids metabolised
Quickly degraded by extracellular proteases hence why you only get short pain relief
