F10_L04_action_potential

F10_L04_action_potential - Psy 111 Basic concepts in...

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Unformatted text preview: Psy 111 Basic concepts in Biopsychology Lecture 4: The Action Potential Electrochemical Equilibrium & Membrane Permeability for an Ion. Nernst Equation E ion = 61.54 x 1 x log [ion] outside z [ion] inside For K+, [ion] outside = 5 mM & [ion] inside = 100 mM E K+ = -80mV. For Na+, [ion] outside = 150 mM & [ion] inside = 15 mM E K+ = +65mV. Resting Membrane Potential Summary At rest, membrane has a large relative permeability to K+ versus Na+ Ion out in Ratio E ion K + 5 mM 100 mM 1:20-80 mV Na + 150 mM 15 mM 10:1 62 mV Cl- 150 mM 13 mM 11.5:1-65 mV V m = (61.54) log P K [K + 0] out + P Na [Na + ] out + P Cl [Cl- ] out P K [K + 0] in + P Na [Na + ] in + P Cl [Cl- ] in For our purposes: there is a population of K+ channels that are always open i.e. non-gated Membrane Potentials in Excitable Cells-50 50 V m-50 50 V m Hepatocyte Neuron Recordings from 2 mSec Today we focus on what is happening when the membrane is active! Objectives ¡ Describe the electrical properties of excitable membranes. ¡ Describe the properties and stages of the action potential. ¡ Define generator potential and threshold and the relation between the two including the relation between magnitude of generator potential and magnitude of neuronal response. ¡ Discuss relation of changes in membrane potential and relative permeability of K+:Na+ during the stages of the action potential. ¡ Identify the “voltage-gated” channels involved in the action potential and the properties of these channels. ¡ Describe relation between vg-Na+ channels and voltage sensitivity. ¡ Describe the positive feedback in generation of action potentials. ¡ Discuss role of vg-Na+ channel inactivation in conduction of action potentials. ¡ Explain the factors determining action potential conduction speed. The Action Potential 1. Properties and description 2. Relative permeablities 3. Ion channels & gating 4. Conduction Description of AP stages 2 mSec 2 mSec Properties and description of the AP AP Generation requires input = “Generator Potential” normally this is derived from neurotransmission (next week) but can be experimentally induced as depicted. Properties and description of the AP...
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This note was uploaded on 12/18/2010 for the course PSYCH 111 taught by Professor Kippen during the Fall '08 term at UCSB.

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F10_L04_action_potential - Psy 111 Basic concepts in...

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