NRSC 2100 1st Edition Lecture 20 Nociception 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 Histamine Nociceptors Types of Nociceptors Polymodal Mechanical Thermal Hyperalgesia Spinal 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 skin Pain Regulation Spinal Afferents and Descending Modulation Gate theory of pain Melzack and Wall These 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 endorphins Thermoreceptors Hot capsaicin receptor Trpv1 43oC Cold menthol receptor Trpm8 25oC Varying sensitivities Usually one receptor to neuron relationship Response of Thermosensitive Sensory Neurons Note the relative responses to increases or decreases in temperature not static Adaptation is also common among temperature cells
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