Nociception and PainPain - feeling of soreness, aching, throbbingNociception - sensory process, provides signals that trigger painNociceptors: Transduction of PainMechanically gated ion channels opened by:Strong mechanical stimulation, temperature extremes, oxygen deprivation, chemicalsDamaged cells release substances that open ion channelsProteases (-> bradykinin), ATP, H+, K+ ion channelsHistamineNociceptorsTypes of NociceptorsPolymodalMechanicalThermalHyperalgesiaSpinal Pain PathwaySegregated from hapsis based on receptors (free nerve endings), speed of conduction (slower), and spinal pathways to brain (contralateral in spinal cord);Pain information from nociceptors synapses onto substantia gelatinosa neurons, which send their axons to contralateral lateral column directly tothalamus“Referred Pain”Spinal cord Substantia gelatinosa neurons receive nociceptive afferents from both viscera and skinPain Regulation: Spinal Afferents andDescending ModulationGate theory of pain - Melzack and WallDescending innervation: serotonin and endorphinsThermoreceptors“Hot” capsaicin receptor (Trpv1 - > 43oC);“Cold”menthol receptor (Trpm8 - < 25oC);Varying sensitivities;Usually one receptor to neuron relationshipResponse of Thermosensitive Sensory NeuronsNote the relative responses to increases or decreases in temperature; not static!Adaptation is also common among temperature cells.NRSC 2100 1st Edition Lecture 20Nociception and Pain– Pain - feeling of soreness, aching, throbbing – Nociception - sensory process, provides signals that trigger pain• Nociceptors: Transduction of Pain – Mechanically gated ion channels opened by:• Strong mechanical stimulation, temperature extremes, oxygen deprivation, chemicals– Damaged cells release substances that open ion channels• Proteases (-> bradykinin), ATP, H+, K+ ion channels• HistamineNociceptors– Types of Nociceptors• Polymodal• Mechanical• Thermal– HyperalgesiaSpinal Pain Pathway• Segregated from hapsis based on receptors (free nerve endings), speed of conduction (slower), and spinal pathways to brain (contralateral in spinal cord);• Pain information from nociceptors synapses onto substantia gelatinosa neurons, which send their axons to contralateral lateral column directly to thalamus“Referred Pain”Spinal cord Substantia gelatinosa neurons receive nociceptive afferents from both viscera and skinPain Regulation: Spinal Afferents and Descending ModulationGate theory of pain - Melzack and WallThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Descending innervation: serotonin and endorphinsThermoreceptors– “Hot” capsaicin receptor (Trpv1 - > 43oC);– “Cold”menthol receptor (Trpm8 - < 25oC);– Varying sensitivities;– Usually one receptor to neuron relationshipResponse of Thermosensitive Sensory Neurons• Note the relative responses to increases or decreases in temperature; not static!• Adaptation is also common among temperature
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