4 pain

Question 1

specificity theory

Answer 1

specific pain receptors and fibers project to the brain
- intensity of pain directly related to amount of tissue injury (needle vs knife)

• doesn’t account for chronic pain or cognitive, emotional elements that contribute to complex pain

Question 2

pattern theory

Answer 2

impulse intensity and repatterning of CNS

• very limited, doesn’t account for all the types of pain experience

Question 3

gate control theory

Answer 3

multidimensional aspects of pain perception and modulation
transmission modulated by impulses conducted to spinal cord
- “gate”: cells in substantia gelatinosa; regulates pain transmission to higher centers (CNS)

fibers respond to stimuli (mechanical, thermal, chemical)

• large, myelinated A-delta fibers
• small, unmyelinated C-fibers
• terminate on interneurons in substantia gelatinosa (laminae in dorsal horn of spinal cord)
• • nociceptive transmissions on fibers open gate, increase pain perception
• • non-nociceptive stimulation = closure/partial closure of spinal gates (ex: rubbing painful area alleviates discomfort)

Question 4

neuromatrix theory

Answer 4

brain produces patterns of nerve impulses drawn from various inputs (genetic, psychologic, cognitive experiences)

• builds on gate control
• phantom pain
• neuromatrix patterns normally activated by sensory inputs from periphery; may originate independently in brain with no external input (stimuli trigger patterns but do not necessarily produce them)

Question 5

nociception

Answer 5

processing of potentially harmful (noxious) stimuli through a normally functioning nervous system

Question 6

transduction

Answer 6

begins when tissue is damaged by exposure to chemical, mechanical, thermal noxious stimuli; converted to electrophysiological activity and activates nociceptors

Question 7

nociceptors

Answer 7

free nerve endings in afferent peripheral nervous system that selectively respond to different stimuli;

located throughout the body but not evenly distributed - relative sensitivity to pain differs according to location;

equipped with array of transduction channels that can sense different forms of noxious stimulation at different intensities