Lecture 3 - Neuronal Signaling electrical signals of nerve cells voltage-dependent membrane permeability channels and transporters synaptic

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Neuronal Signaling • electrical signals of nerve cells • voltage-dependent membrane permeability • channels and transporters • synaptic transmission • neurotransmitters, receptors, and their effects • molecular signaling within neurons
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Intracellular recording An electrode is placed inside a cell that is connected to a voltmeter which records transmembrane voltage across the cell membrane. When one does this in neurons, the microelectrode reports a negative potential called the resting potential. Always a fraction of a Volt (-40 to -90 mV). Volts are a unit of electrochemical potential. 1 Volt will drive 1 coulomb of charge (6.24X10 18 electrons) through a resistance of 1 ohm in 1 second.
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Electrical signals Can be generated by response to stimuli, which can change the resting potential of the neuron. Two main types of ways to change a neuron’s resting potential. Receptor potentials can be generated from the activation of sensory receptors, from touch, light, sound, and heat. Synaptic potentials are transmitted from one neuron to another at the synapse. Action potentials are the booster system to propagate electrical signals through a long distance.
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Important terms • Resting membrane potential- voltage across the cell membrane when it is at rest. Typically -40 to -90 mV. • Hyperpolarization- the membrane potential of a cells is more negative than at rest. • Depolarization- more positive than at rest. • Threshold potential- potential at which an action potential is initiated.
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• PN02011.JPG Recording Passive and Active Electrical Signals in a Nerve Cell Can inject current into the cell. Can add positive charge or negative charge. This will change the resting potential accordingly.
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Recording Passive and Active Electrical Signals in a Nerve Cell inject negative charge inject positive charge action potentials all have basically the same amplitude stronger stimulus give more AP’s not stronger ones
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Resting Potentials of Neurons The Membrane of a Nerve Cell Maintains an Electrical Polarization outside (+) The cell is polarized : at rest, an electrical gradient is maintained across the plasma membrane (negative charge is greater inside the cell) The cell has a resting potential : difference in voltage across the membrane of a cell (~ -70 mV) The cell has a concentration gradient : difference in distribution of ions between the inside and outside of a membrane inside (-)
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This document was uploaded on 02/28/2011.

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Lecture 3 - Neuronal Signaling electrical signals of nerve cells voltage-dependent membrane permeability channels and transporters synaptic

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