Pain Relief and Anesthesia



Pain Relief and Anesthesia

Pain: -results from stimulation of free nerve endings

(neurons) in skin and visceral (internal) tissues

- generally receptors have a high threshold of

stimulus

- certain chemical substances may be release by injured tissues which intensify pain

e.g.: histamines, prostaglandins

- pain signals are interpreted by the cerebral cortex,

limbic system (primitive brain), and thalamus

How can pain be relieved?

( Several ways:

- interfere with neurotransmitter molecules

e.g.: morphine

- afferent pain inhibition (“gate theory”)

e.g.: pressure, acupuncture

- other pain relievers like Aspirin®

- anesthesia

How does Aspirin® work?

( Aspirin acts on an enzyme involved in making certain

chemicals called prostaglandins that play a role in pain and

inflammation

( Enzyme is called cyclooxygenase 2 (Cox-2)

( If FEWER prostaglandins are being released, then this

decreases pain signals sent to the brain

BUT…

( In some tissues prostaglandins are needed for normal

function

e.g.: blood clotting

- blood takes longer to clot when taking Aspirin®

maintenance of stomach lining

- risk of stomach irritation or ulcer

How does Anesthesia work?

Anesthesia = partial or complete loss of sensation, with OR

without loss of consciousness

Local anesthetics:

- may be injected or applied to skin at site where effect is desired

- generally block nerve impulse transmission by decreasing the permeability of the neurons to sodium ions

General anesthetics:

- not as well understood at the cellular level

- generally affect spinal cord (immobility), brain stem (unconsciousness), and cortex (pain signal interpretation)

- may act by altering sodium permeability

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