PSYC 100 Study Guide - Central Nervous System, Magnetic Resonance Imaging, Limbic System
3 Oct 2013
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Document Summary
Cell body (soma): contain biochemical structures for life of neuron and genetic info. Glial cells: support and protect neurons from toxins. Myelin sheath: white fatty insulation layer derive from glial cells during development. Node of ranvier: areas of thin or no myelin sheath. At rest, neuron has resting potential (-70mv), due to the balance of + and - chemical ions inside and outside the neuron. Neuron at rest is in a state of polarization. When stimulated, neuron reverses resting potential, causes action potential (40mv) Action potential: sodium channels open, neuron become + quickly, releases positive potassium to balance, then undergoes an absolute refractory period where neuron is at a recovery phase and no pulse can be sent. Shift from negative to positive voltage is called depolarization. All or nothing law: action potentials occur at a uniform and maximum intensity or do not occur at all. This pulse must reach -50mv to trigger action potential. (action potential threshold)
