PAIN MODALITY

B. Stimulus-Response Mechanisms (==>)

1. Direct mechanical (or mechanical-thermal) receptors probably associated with sharp pain; chemically mediated pain (polymodal) receptors probably associated with dull pain

2. When stimulated, pain endings can release the neurotransmitter/vasodilator Substance P (SP)  (!)

3. Note positive feedback: nociceptor activation <=> inflammation; results in nociceptor sensitization (peripheral sensitization)

4. Note effect of nociceptor stimulation on local blood flow increase (axon reflex, red flare) (==>)

5. Prostaglandin synthesis inhibitors (cyclooxygenase inhibitors) can act as analgesics (==>)