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Published byArleen Harrison Modified over 8 years ago
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بنام آنكه جان را فكرت آموخت
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Neurochemistry of Pain Sensation References: - Essentials of Pain Medicine (Benzon) - Principles of neural science (Kandel) - Textbook of Medical Physiology (Guyton) By: Dr H. Najafi, Associate Professor, medical physiology.
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pain Types of pain The sequence of events by which a stimulus is perceived - Transduction - Transmission - Modulation - Perception
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Pain receptors and their stimulation by inflammatory soup
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Neurochemistry of somatosensory processing at peripheral sensory nerve endings CGRP NO: released by damaged afferents, further sensitize nearby neurons, augmenting pain and inflammation. Peripheral anti- hyperalgesic mechanisms Capsaicin
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Peripheral Second Messenger Pathways
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Cyclic adenosine monophosphate (cAMP) second messenger (G s )
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The cell membrane phospholipid second messenger system (Gq)
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Physiologic classification of nerve fibers
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Dual pathway for transmission of pain (Neospinothalamic) (paleospinothalamic) Anterior commissure
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Transmission of the pain into the brain stem, thalamus and cerebral cortex -Reticular areas -Ventrobasal complex -Posterior nuclear groups of the thalamus 1- Reticular nuclei 2- The tectal area 3-The periaqueductal gray region - Intralaminar and ventrolateral nuclei of the thalamus Capability of pain signal to arouse nervous excitability
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Neurochemistry of somatosensory processing in the spinal dorsal horn
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Neurochemistry of pain transmission in spinal cord Excitatory Neurotransmitters: - Glutamate and aspartate - ATP - Substance P and neurokinin A - CGRP - CCK
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Inhibitory Neurotransmitters - Glycine and GABA - Norepinephrine (Alpha-2 Clonidine) - Serotonin - Adenosine - Acetylcholine - Somatostatin, the enkephalins, and possibly dynorphin
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Descending pathway for modulation of nociception at the supraspinal level
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Supraspinal modulation of nociception Pain matrix (anterior cingulate cortex, amygdala, and prefrontal cortex) Periaquaductal gray (PAG) Rostral ventromedial medulla (RVM): On cells and Off cells Dorsal root ganglion +-+-
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Analgesia system of the brain and spinal cord
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Inhibition of pain transmission by tactile sensory signals
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The localized modulation of pain can be explained by the gate control hypothesis
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Nonadapting nature of pain receptors (Hyperalgesia)
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Hyperalgesia Peripheral (primary) (Histamine, Bradykinin, PG. E2, Sbs. P) Central (secondary)
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Peripheral hyperalgesia
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Central hyperalgesia
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Referred pain
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Causes of True Visceral Pain Ischemia Chemical Stimuli Spasm of a Hollow Viscus Overdistention of a Hollow Viscus
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Mechanism of referred pain
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Visceral and parietal transmission of pain from the appendix
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Surface area of referred pain from different visceral organs
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Thanks for your attention
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