chapter seven part one

what is congenital analgesia

a disease where people do no experience pain

what is pain defined as

an unpleasant sensory and emotional experience associated with actual or potential tissue damage

what would happen if we couldn’t feel pain

we wouldn’t know that something was wrong

what is the order of the ascending pain pathway

nociceptors detect, travels to dorsal horn of spinal cord, crosses to opposite side of stimulus, up to thalamus where they synapse, then sent to the somatosensory cortex

what does the somatosensory system do

convey all sensory information from periphery to central system

what are nociceptors

skin and organs capable of responding to various types of stimulation that may cause tissue damage

what is an a-delta fiber

myelinated axons that have ability to travel 150 meters per second; sharp and localized pain

what are c-fibers

fibers that make up 60% of the sensory system, traveling at 10 meters per second; slow and burning pain

true or false: pain is processed on the opposite side that it occurs

true

what is the thalamus

the sensory relay station; where all sensory synapses besides sense of smell

what are the two parts of the somatosensory cortex

primary and secondary

where are the somatosensory cortexes located

in the parietal lobe, begins next to the central sulcus

how is the somatosensory cortex organized

hierarchically; moving from primary to secondary we get more information

what does the primary cortex do

precisely identify where stimulation is occuring

what does the secondary cortex do

recognize the stimulation as pain

who is homunculus (dwarfish man)

a fictional representation of how much your cortex devotes neurons to certain parts of your body; enlarged face and fingers

what is the process of early pain signals

when a-delta fibers make it rapidly to brain, then primary for discrimination of location, then secondary for pain recognition

what is the process of late pain phase

due to c-fibers, cells go to area of a-fibers and the anterior cingulate cortex; part of limbic system where suffering occurs

where is the anterior cingulate cortex located

above corpus callosum

what is the process of the descending pain pathway

signals are sent to the PAG, which projects signals to the locus coeruleus and raphe nuclei to release neurons, those neurons travel to the spinal cord where endogenous opiates are released

what is locus coeruleus

part of the brain that releases norepinephrine

what is the raphe nuclei

part of the brain that produces and releases serotonin

what do the axons from the l.c. and r.n. do

inhibit substance p and enhance release of endogenous opiate

what does substance p do

stimulate nociceptors; inhibiting it blocks pain signals

where is the gate control theory of pain located

in the substantia gelatinosa

examples of endogenous opiates

beta endorphins, enkephalins, dynorphins, and nystatin (1975)

what is the importance of nystatin

it’s probably the thing controlling the gate in the spinal cord

function of PET scan

to detect activity in your brain as it’s being processed

the more active your brain is you =

accumulate more glucose = more radioactivity