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Flashcards in 6.5 Pain physiology and pharmacology Deck (14)

What are the two types of peripheral nerves?

A delta fibres: lightly myleinated, relatively fast, high threshold mechanoreceptors

C fibres: non myelinated, slow, specific nociceptors


Where do A delta and C fibres enter the spinal cord and what kind of pain do they transmit?

A: lamina V - acute pain and temperature
C: Lamina II substantia gelatinosa - slow burning pain


What are the ascending pain and temperature fibres?

Lateral: paleospinothalamic
Anterior: neospinothalamic


Where do the paleospinothalamic and neospinothalamic project?

Paleo:post central gyrus
Neo:post central gyrus, reticular formation, medulla, limbic system


What are the targets for the descending pathways of pain?

inflammation, conduction, synapse and central perception and descending pathways


Where are opiod receptors located?

Brain, brainstem, spinal cord, peripheral neurons and intestine


How do opioids work?

They work on opioid receptors which are G coupled receptors - Inhibit this which leads to inhibition of voltage gated Ca channels and reduced NT release presypatically

Increase in potassium conductance an membrane hyperpolarisation post synaptically


What effect do opioids have on brain receptors?

Decrease firing of GABAergic neurons leading to disinhibition of descending pathways which inhibits spinal pain transmission


What are the CNS and GIT side effects of opioids?

CNS: sedation, euphoria, respiratory depression

GIT: nausea, vomiting, constipation


What is the role of the COX enzyme?

Convert arachidonic acid to prostaglandins


How can pain be assessed?

Pain score
Functional pain assessment
Physiological assessmnet


What are the two principles of biological pain treatment?

Treat reversible physiology
Provide pharmacological analgesia both systemic and regional


What is the holy trinity of pain management?

Paracetamol, NSAIDs and opioids


What are the 3 tiers of analgesia?

1: paracetamol, NSAIDs, opioids
2: ketamine, tramadol, clonidine, gabapentinoids
3: local anaesthetics