PHGY 214 Lecture Notes - Lecture 9: Mecha, Capsaicin, Thalamus
8 Dec 2017
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Document Summary
All get put in a-beta fibers (myelinated, large diameter and fast: free nerve endings: slow, pain, temp, crude touch, hair moves follicle wrapped in free nerve ending switch paccinian and ruffini. Transduction: sensory neuron w specialized ending: stim (pressure) deforms receptor, na+ chan open and depol memb, if generator or receptor potential exceeds threshold, ap generated along axon. Direct activation of na chan via: lipid proteins (memb stretch) structural proteins. Neural response (rate of spikes) adapts b/c the receptor potential adapts. Memb likely slips back twrd orginial shape closing chan, some charge in biophysical prop of ion chan. Enhances detection of changes in pressure, allows us to stop processing unchanging events, ex pressure of clothes. Put needle right beside nerve fiber so it can measure the ap. Intensity: pressure is coded non-linearly, low discriminability at high pressures- means eventually flattens out. Small change is pressure can lead to many aps. Free nerve endings w temp sensitive ion chans.
