PHSI2005 Study Guide - Final Guide: Sciatic Nerve, Axon Hillock, Reference Electrode
15 Jan 2019
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Document Summary
Generating action potentials in vivo and in vitro (cid:120) (cid:120) In vivo, an ap is triggered when the summation of graded potentials at the axon hillock depolarises the membrane to threshold. In vitro, the nerve fibres/axons are stimulated to fire aps by applying a depolarising current: note: nerves are a collection of axons and do not contain dendrites or soma. Intracellular recording of a single neuron measures the change in transmembrane voltage that occurs during an ap using an intracellular electrode that penetrates the cell membrane, and a second electrode placed outside the cell as a reference electrode. The potential difference between the two electrodes is then recorded (cid:120) extracellular recording of a whole nerve calculates the potential difference between two extracellular electrodes. Aps reaching the second recording electrode, so once the ap has passed the first recording electrode, the tracing returns to baseline.
