Psychology 1000 Study Guide - Quiz Guide: Morphine, Amygdala, Cultural Learning
4 Jun 2018
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Biological Mechanisms of Pain
• Pain receptors are found in all body tissues expect for brain, hair, nails, and nonliving
parts of the teeth.
• Nerve endings in the skin and internal organs respond to intense mechanical, thermal,
or chemical stimulation and sends nerve impulses into the spinal chord, where sensory
tracts carry pain information to the brain.
• In the brain, sensory information about pain intensity and location is transmitted
(relayed) by the thalamus to the somatosensory and frontal areas of the cerebral cortex.
o Pain receptors (respond to stimuli) impulses sent to spinal chord brain
thalamus 1. Somatosensory & frontal cerebral cortex 2. limbic system
• Other tracts from the thalamus direct nerve impulses to the limbic system, which is
involved in motivation and emotion.
• These tracts seem to control to the emotional component of pain – pain has a sensory &
emotional component.
• Suffering – both painful sensations and negative emotional response are present
Gate Control Theory:
• Melzack & Wall theory – major advance in the study of pain
• Gate control theory – experience of pain results from the opening and closing of
gating mechanisms in the nervous system.
• Sensations from 2 types of sensory fibres enter the spinal chord, where they can
activate neurons that travel up toward the brain regions responsible for our perception
of pain.
• Some of these fibres are very thin in diameter, whereas others are thicker
• Thin fibres carry sharp-pain impulses; thick fibres convey dull pain and touch
information.
• Whether we experience pain depends partly on the ratio of thin-to-thick fibre
transmission
• Relatively high levels of thin-fibre activity open a system of spinal chord gates
allowing the nerve impulses to be sent to the brain and thick-fibre activity closes the
gates.
• Our perception of pain can be decrease by increasing thick-fibre nerve impulses
o Scratching an itch stimulates thick fibres producing relief
• Psychological perspective – intriguing feature about gate theory – nerve impulses in
fibred descending from the brain can also influence spinal gates, which increase or
decrease the flow of pain stimulation to the brain.
• This central control system allows thoughts, emotions, and beliefs to influence the
experience of pains and helps explain why pain is a psychological and physiological
phenomenon
The Endorphins:
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