Pain

Question 1

Peripheral pain receptors

Answer 1

nociceptors (Adelta or C), silent, thermoreceptors, mechanoreceptors

Question 2

inflammatory mediators

Answer 2

e.g. PGs, LTs, bradykinin which are released after tissue injury
decrease TH of regular nociceptors
recruits silent nociceptors
activation of axon reflex

Question 3

axon reflex

Answer 3

If a stimulus is of great enough, it can trigger the trigger zone, which will shoot an AP retrograde, causing the release of NTs from the dendrites, further causing dilation and edema and reducing the TH of the neuron and activating silent receptors

Question 4

modulating pain threshold at the dorsal horn (wind up)

Answer 4

glutamate, Sub P, BDNF acting on NMDA changes the membrane sensitivity of second order neurons, making them more sensitive to glut release (causes allyodonia or hyperalgesia)

Question 5

gate control theory

Answer 5

explains why rubbing after a painful stimulus decreases pain

tactile stimuli neurons have axo-axonal connections that inhibit wide dynamic range neurons (which also carry painful stimuli)

Question 6

central modulation by descending pathways

Answer 6

The PAG sends signals down the RM in the caudal pons, which run down to the dorsal horn where they release opioids