Pain

Somatosensory processing II

sharp cutting pain

neospinothalamic

dull burning pain

paleospinothalamic

deep aching pain

archispinothalamic

warm/hot

paleospinothalamic

cool/cold

neospinothalamic

itch/tickle and crude touch

paleospinothalamic

What is nociception?

the neural encoding and processing of noxious stimuli

Noxious stimuli are stimuli that can

elicit tissue damage and activate nociceptors

Nociceptors are

sensory receptors that detect signals from damaged tissue (or the threat of damage)

Nociceptors also respond to

chemicals released from the damaged tissue

Nociceptors are

free bare nerve endings found in the skin, muscle, joints, bone

What is responsible for normal stimulation?

Peripheral axons

Peripheral axons do not

increase their frequency in response to painful stimuli

Nociceptive afferents only fire when

stimuli reach high intensities

direct stimulation of large fibers does not

produce pain

peripheral nociceptive axons terminate in

free endings

nociceptors are found on

small fibers A delta and C fibers

A delta fibers respond to intense

mechanical and thermal stimuli (type I and II nociceptors)

C fibers are ____

polymodal

C fibers respond to

thermal, mechanical, and chemical stimuli

Type I A delta fibers respond to

dangerous mechanical and chemical stimulation

Type I A delta fibers do not respond well to

heat

Type II A delta fibers respond to

thermal stimulation (heat)

Type II A delta fibers do not respond well to

mechanical and chemical stimulation

C fibers are

polymodal

C fibers respond how to noxious stimuli

equally to all types of noxious stimuli

The first sharp pain results from

A delta fibers

Second dull pain results from

C fibers

Epicritic pain

sharp first pain

Proptopathic

dull second pain

A delta vs C fibers m/s

A delta: 5-30

C fibers: <1