Pain

Question 1

A-delta fibers

Answer 1

Transmit info from peripheral cutaneous structures. Transmit pain signals that are sharp and localized.

Question 2

C fibers

Answer 2

Transmit info from deeper tissues (joints, viscera) and do so more slowly than A-delta fibers.
They transmit pain signals that are dull, aching, and diffuse.

Question 3

Gate control theory

Answer 3

 A-delta and C fibers synapse with a secondary neuron and inhibitory interneuron.
 A-alpha and A-beta fibers provide input to inhibitory interneurons; nerve transmission through these fibers can stimulate interneurons to inhibit pain signals to brain.
 Massage and electrical stimulation work on this theory by stimulating A-alpha and A-beta fibers.

Question 4

Endogenous Opioids

Answer 4

 Opioids have a direct effect on nerve signals by controlling the amount of calcium and potassium that move into and out of the cell during depolarization.
 They have an indirect effect on nerve signals by inhibiting the release of GABA, a substance that inhibits the activity of structures to control pain, including A-beta fibers.