Pain – Anatomy and Physiology. Definition. An unpleasant sensory and emotional experience... ...caused by actual or potential tissue injury, ...or described in terms of such injury. International Association for the Study of Pain. Sources of Pain.
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An unpleasant sensory and emotional experience...
...caused by actual or potential tissue injury,
...or described in terms of such injury.
International Association for the Study of Pain
Nociceptive: pain that is usually transmitted after normal processing of noxious stimuli
Neuropathic: results from injury or abnormal functioning of peripheral nerves or CNS
Psychogenic: unknown physical cause
Electrical Activity to spinal cord and onto the Brain
BRAIN = Electrical activity becomes the experience of
Sensitive to touch & vibration
Meissner’s corpuscles –
Sensitive to light touch & vibrations
Pacinian corpuscles -
Sensitive to deep pressure & vibrations
Deep subcutaneous tissue location
Krause’s end bulbs –
Sensitive to touch & tension
Free nerve endings -
Detects pain, touch, temperature, mechanical stimuliNerve Endings
Transduction Conduction Transmission
primary sensory neuron central neuron
Gate (T cells/ SG)
Heat, Cold, Mechanical
within the dorsal horn.
Primary afferent neuron
axons synapse onto
and onto inhibitory and
Physical cause — cause of pain can be identified
Psychogenic — cause of pain cannot be identified
Referred — pain is perceived in an area distant from its point of origin
Is the lowest intensity of stimulus that causes the subject to recognize pain
Physiologic: ↑BP, ↑HR,↑RR, pupil dilation, muscle tension and tension rigidity, pallor, ↑adrenaline level, ↑blood glucose
Behavioral: grimacing, moaning, crying, restlessness
Affective: exaggerated weeping, withdrawal, anxiety, depression, fear, anger, anorexia, fatigue, hopelessness, powerlessness.
Family, gender, and age variables
Environment and support people
Anxiety and other stressors
Past pain experience
Remove or alter cause of pain
Alter factors affecting pain tolerance
Initiate nonpharmacologic relief measures
Nonopiod analgesics e.g. NSAIDs
Opioids or narcotic analgesics
Adjuvant drugs e.g. anticonvulsants, antidepressants, ..
Patient controlled analgesia
Spinal Dorsal Horn
TENS Dorsal Horn
If the body doesn’t sense the pain during the procedure, the pain will be easier to deal with post-operatively
A patient in surgical anesthesia is not aware of pain, but the body is still responding sensitizes the nervous system
Excites then fatigues nerve transmissionlocal analgesia
Also get endorphin release
Stimulates neural inhibitory pathways analgesia