Pain

Nerve cells in the spinal cord

-allows A delta fiber and C fibers merge together affecting each other. This is how acupuncture works and deals with dull pain, needles placed to stimulate A delta fibers that will inhibit input from C fiber.

Phantom Pain

-people with limbs removed, pain in area of missing limb -thalidomide, sedative during pregnancy resulted in babies without limbs, pain in limbs they never had -there is pain in limbs once had, and limbs never hand (thalidomide babies). -proprioceptive when missing a limb -physical limb and concept of the limb. usually congruent and not seen as distinct. Concept of arm still there once the limb is removed. stroke: have the limb but no concept of the limb phantom pain: no limb but have concept of the limb

Response and perception of pain

-range of responses to pain, the curve suggest little variation in terms of perception of pain!

Absence of treating pain

1) Brief Injury → CNS → PAIN (analgesic at level of receptor) 2) Infection/ inflammation → CNS (spinal cord) hyperalgesic effect with chronic pain → persisting (morphine is effective) failure to treat pain leads to pain generated by the CNS not by the peripheral receptors: 3) feather → pain perceptive pathways damaged- nerve or CNS damage (chronic pain) → abnormal (intractable pain, resistant to morphine, lipid soluble)

Pain in visceral area

Different than pain in the skin. Referred pain: pain due to ulcers, heart attack- distributed to different parts of the body -skin to spinal cord → nerves from various organs send to the same dermatome, sensation of heart attack perceived as pain in certain parts of skin due to overlap. Information from the skin and the viscera come at the same level.

Withstand more pain that others...

False! Pain happens when tissue damage is occuring

Spinalthalamic tracts

Lateral and Anterior. Spine to the thalamus (pain receptive center in the brain). -physical pathway does not need to be activated to experience pain.

Interactions

Two fiber types can interact. A can inhibit C, potential source of impeding the dull component pain. Idea of accuouncture- blocking C fiber.

Experiment with the hypnotist

Valid

Hot Plate experiment

Withdraw hand around 44 to 46 degrees C. Cells start to release substances, particularly kinins→ bradykinin is a stimulator free nerve endings, which is where pain is sensed.

Aspirin and pain vs. Morphine

affects the activity of the pain sensor/receptor, reducing sensitivity -morphine acts centrally! crossing the BBB changes the way the way the brain perceives pain, impulses still come in but not processed the same way

Pain conduction

conducted by pain receptors, free nerve endings 1) A delta fibers (myelinated, fast conducting- acute pain) 2) C fiber (unmyelinated, slower- second surge) peripheral nervous system fibers

Pain is a dual system: a delta fibers and c fibers

reflexive and dull pain a delta fibers: myelinated, faster, acute pain alpha to delta: get smaller and smaller a delta fibers: -myelinated, fast conducting, phasic- rate of firing decreases as constant stimulus is applied(one that adapts- decreases intensity over time) -responsible for sharp well localization of pain c fibers: -unmyelinated, slower to conduct impulses to the brain, tonic- conducting impulses all the time and does not fad, dull pain, poorly localized, more difficult to address- need to add heavy duty drugs that cross the BBB

Pain Scale

standard practice to report pain. indicator of well being.

A and C delta fibers

two phase sensation of pain A- acute, sharp, well localized C- dull component of pain, associated with chronic pain

a alpha fibers

LARGER nerve: faster conducting a alpha fibers: largest fibers in the body, fast conducting, attached to fast muscles of locamotion

Anesthesia

Patient controlled anesthesia. self administered -great for chronic pain