Chapter 13

Pain- A Fundamental Stress

Pain: Urgent Signals

• Hunger, Thirst, Breathing

• Muscles, Joints, Heart, Stomach

• Wounds, Damage, Swelling

• Headaches,

• Worry, Fret, Anxiety

Pain

• A signal

• Important information for the brain

• A signal that can’t be ignored

• Localizable

Pain Signals

• Pain receptors

• Spinal cord

• Nerves

Pain Stimuli

• Stretch

• Damage

• Reduced blood flow

Reflex to Pain

Fast Track Sympathetic Reflex

Slow track Attention

Localization

Referred Pain

Physiology of Pain Control

Proopiomelanocortin mRNA

ACTH Endorphin

Enkephlin

Message Splicing

Pain Control

Why?

A Medical Problem

Pain Control

• Generation of pain signal

• Transmission of pain signal

• Sympathetic response to pain

• Long term stress response

• Perception of pain

• Limbic response to pain

Non-drug Methods

• Bit the bullet: competition for attention in the reticular core of the brain

• acupuncture

Local Anesthetics

• Uses– Creams - pain receptors– Inject into the area of the nerve– Spinal block

Local Anesthetics

• Oily compounds

• Dissolve into membranes

• Disrupt membrane function in the area

• Removed by circulation

• Novocain, lidocain, tetracain

• Penetrance, potency, and metabolism

anesthetic

Block signal from getting to the central nervous system

Side Effects

• Spinal block – headaches

• All uses – general depressant

• Other excitable tissues

Non-Narcotic Analgesics

• Over the counter

• Low level pain

• Do not alter consciousness

Aspirin-like Compounds

• Prehistory- willow bark tea

• Good for headaches, muscle aches, joint pain

• Not good for internal organ pain due to stretch

• Blocks COX1 and COX2 – prostaglandin synthesis

Aspirin-like Compounds Side Effects

• Reduces fever

• Reduces inflammation

• Inhibits blood clotting

• Increases respiration

• Irritates stomach

• Reye’s syndrome

Acetaminophen

• Older drug was phenacetin which was converted by liver to acetaminophen

• Only blocks prostaglandin synthesis in the CNS not peripheral

• Not anti-inflammatory

Acetaminophenside effects

• Reduces fever

• Liver toxicity

• Kidney toxicity

• Other drug interactions (eg alcohol)

Ibuprofen and Naproxen

• Formerly prescription (dosage)

• Interferes with prostaglandin synthesis

• Reduces fever

• Reduces inflammation

• Rare toxic amblyopia

Narcotic Analgesics

• Intense pain

• Opium – from the unripe seed pod of a type of poppy

• Morphine, codeine (natural)

• Heroin, dihydromorphine (semi-synthetic)

• Methadone, meperidine (synthetic)

Pain Threshold

A Balance

Opiate Receptors

• Pain paths in spinal cord

• Medulla (breathing)

• Hypothalamus

• Limbic system

• Frontal and temporal lobes

• Reticular core

• Outside CNS – digestive system

Opiate Use

• Short term intense pain

• Why not long term?– Tolerance– Dependence– Addiction

Opiate Side Effects

• Suppresses drives – hunger, thirst, sex

• Hypothalamic control of temperature and hormones

• Medulla control of breathing

• Stimulates emetic reflex

• Inhibits cough reflex

• Pin point pupils

Pain

• Urgent signals

• Balance of important priorities

• Useless pain