Pain Flashcards
Which nociceptors are responsible for fast and sharp pain?
A-delta fast pain receptors
Which receptors are responsible for slow and dull pain?
C slow pain receptors
Which pain receptors are acute and which chronic?
Fast= acute
Slow= chronic
What are other types of pain?
Deep, visceral, referred and phantom
What is the key structural difference between C and A-delta fibres?
C fibres are unmyelinated whereas A-delta fibres are myelinated
Which stimuli can activate pain fibres?
Temperature, pH and chemicals
Where do nociceptive fibres synapse?
Dorsal horn
What is the course of the projection neurones in the CNS?
They cross the midline and travel up the anterolateral spinothalamic tract
Where do projection neurons synapse?
Thalamus and cortex for fast pain
Reticular formation for slow pain
What is the key difference between where sensory receptors and nociceptor projection neurons cross the midline?
Nociceptors cross almost as immediately after the nociceptive fibre
Sensory cross at the base of the skull
How does the gate control theory reduce pain?
A-alpha/beta touch receptors, when activated, inhibit ascending nociceptive fibres via a collateral neuron.
Which analgesic device works on the gate control principle?
TENS
Transcutaneous Electric Nerve Stimulation
What is the descending control theory of analgesia?
When the periaqueductal grey matter is activated by nociceptive pathways, it signals the nucleus raphe magnus to send descending inhibitory signals to nociceptive fibres.
What is allodynia?
Neuropathic (peripheral nerve) pain
What is hyperalgesia?
Hyper sensitivity to pain
Which mechanism is thought to maybe induce allodynia and hyperalgesia?
long term potentiation and plasticity
The NSAID drugs are part of which class of drugs?
Antipyretic, Anti-inflammatory and analgesic
How do NSAIDs exert a response
They inhibit cyclooxygenase which inhibits prostaglandin production. This prevents the sensitisation of bradykinin receptors
Which properties does paracetamol have?
Antipyretic and analgesic
What is the mechanism of action of paracetamol?
It is unknown
How does gabapentin induce analegisa?
Blocks presynaptic voltage-gated Ca2+ channels re-uptaking GABA
What is the problem with conotoxin-derived peptide analgesics?
Peptides cannot be taken orally, they must be delivered intrathecally
