Opioids Flashcards
What is an opioid?
Dugs that promote analgesia (reduction of pain) without anaesthesia but promote a sense of relaxation and sleep and at over doses lead to coma and death.
What are the 3 classes of opioid?
Opiates - extract of opium plant directly derived from opium.
Related semisynthetic and synthetic compounds.
Endogenous peptides acting on the same receptors - opioid receptor.
Describe the mechanisms of opioid action.
Activation of opioid receptors tends to inhibit neural activity or neurotransmitter release of the neurons carrying the opioid receptor
What is meant by nociception?
The neural process of encoding noxious stimuli - stimuli causing tissue damage.
What is meant by chronic pain?
Pain that last or recurs for longer than 3 months
Describe the ascending pain pathway.
Noxious stimuli is fed to the brain via ascending pathways which originate in the primary sensory neurons which detect noxious from the periphery of the body which sit on the dorsal root ganglion and pass info on through the spinal cord and up to the cortex to experience pain.
Describe the 2 ascending pain pathways.
- First/fast pain - originates in the PSN with adelta fibres and ends in the somatosensory cortex.
- Second/slow/late pain - originates in PSN with c fibres and ends in other cortical and subcortical areas.
Describe the descending pain pathway.
Originates in mid brain regions - periaqueductal gray - they inhibit pain processing.
this pathway is modulated by cortical and subcortical regions.
Describe the reinforcing properties of opioids.
Opioids increase DA release in the accumbens by inhibiting the inhibitory neurons. This leads to the disinhibition of DA neurons, increasing DA release.
