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Definition
| passage of an electrical current from the uninsulated tip of an electrode through tissue, resulting in changesin the electrical activity of the tissue |
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| device that measures the flow and the strength of electrical voltage by recording the difference in electrical potential between two bodies |
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| electroencephalogram (EEG) |
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Definition
| graph that records electrical activity through the skull or from the brain and represents graded potentials of many neurons |
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Definition
| device that serves as a sensitive voltmeter by registering the flow of electrons to measure voltage |
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| a microscopic insulated wire or a salt-water filled glass tube of which the uninsulated tip is used to stimulate or record from neurons |
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Definition
| movement of ions from an area of higher concentration to an area of lower concentration through random motion |
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Definition
| differences in concentration of a substance among regions of a container that allow the substance to diffuse from an area of higher concentration to an area of lower concentration |
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Definition
| difference in chage between the two regions that allows a flow of current if the two regions are connected |
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| electrical charge across the cell membrane in the abscence of stimulation; a store of energy produced by a greater negative charge on the intracellular side relative to the extracellular side |
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Definition
| small voltage fluctuation in the cell membrane restricted to the vicinity on the axon where ion concentrations change to cause a brief increase or decrease in electrical charge across the cell membrane |
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Definition
| increase in electrical charge across a membrane, usually due to the inward flow of chloride ions or the outward flow of potassium ions |
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Definition
| decrease in electrical charge across a membrane, usually due to the inward flow of sodium ions |
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| large, brief reversal in the polarity of an axon |
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Definition
| voltage on a neural membrane at which an action potential is triggered by an opening of sodium or potassium voltage-sensitive channels |
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| voltage-sensitive channel |
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Definition
| gated protein channel that opens or closes only at specific membran voltages |
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Definition
| refers to the state of an axon in the repolarizing period during which a new action potential cannot be elicited because gate 2 of sodium channels, which is not voltage-sensitive, is closed |
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Definition
| refers to the state of an axon in the later phase of an action potential during which increased electrical current is required to produce another action potential; a phase during which potassium channels are still open |
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Definition
| propogation of an action potential on the membrane of an axon |
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Definition
| the part of an axon that is not covered by myelin |
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Definition
| propogation of an action potential at successive nodes of ranvier; saltatory means "jumping" or "dancing" |
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Definition
| illness resulting from the loss of the immune system's ability to discriminate between foreign pathogens in the body and the body itself |
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Term
| excitatory postsynaptic potential |
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Definition
| brief depolarization of a neuron membrane in response to stimulation, making the neuron more likely to produce an action potential |
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| inhibitory postsynaptic potential |
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Definition
| brief hyperpolarization of a neuron membrane in response to stimulation, making the neuron less likely to produce an action potential |
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Definition
| graded potentials that occur at approximately the same time on a membrane are summated |
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Definition
| graded potentials that occur at approximately the same location and time on a membrane are summated |
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| reverse movement of an action potential into the dendritic field of a neuron; postulated to play a role in plastic changes that underlie learning |
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| stretch-sensitive channel |
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Definition
| ion channel on a tactile sensory neuron that activates in response to stretching of the membrane, initating a nerve impulse |
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Definition
| on a muscle, the receptor-ion complex that is activated by the release of the neurotransmitter acetylcholine from the terminal of a motor neuron |
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Term
| transmitter-sensitive channel |
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Definition
| receptor complex that has both a receptor site for a chemical and a pore through which ions can flow |
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