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intro to neuroscience
Kolb and Whishaw Chapter 4
29
Psychology
Not Applicable
12/03/2011

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Term
electrical stimulation
Definition
passage of an electrical current from the uninsulated tip of an electrode through tissue, resulting in changesin the electrical activity of the tissue
Term
voltmeter
Definition
device that measures the flow and the strength of electrical voltage by recording the difference in electrical potential between two bodies
Term
electroencephalogram (EEG)
Definition
graph that records electrical activity through the skull or from the brain and represents graded potentials of many neurons
Term
oscilloscope
Definition
device that serves as a sensitive voltmeter by registering the flow of electrons to measure voltage
Term
microelectrode
Definition
a microscopic insulated wire or a salt-water filled glass tube of which the uninsulated tip is used to stimulate or record from neurons
Term
diffusion
Definition
movement of ions from an area of higher concentration to an area of lower concentration through random motion
Term
concentration gradient
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
Term
voltage gradient
Definition
difference in chage between the two regions that allows a flow of current if the two regions are connected
Term
resting potential
Definition
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
Term
graded potential
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
Term
hyperpolarization
Definition
increase in electrical charge across a membrane, usually due to the inward flow of chloride ions or the outward flow of potassium ions
Term
depolarization
Definition
decrease in electrical charge across a membrane, usually due to the inward flow of sodium ions
Term
action potential
Definition
large, brief reversal in the polarity of an axon
Term
threshold potential
Definition
voltage on a neural membrane at which an action potential is triggered by an opening of sodium or potassium voltage-sensitive channels
Term
voltage-sensitive channel
Definition
gated protein channel that opens or closes only at specific membran voltages
Term
absolutely refractory
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
Term
relatively refractory
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
Term
nerve impulse
Definition
propogation of an action potential on the membrane of an axon
Term
node of ranvier
Definition
the part of an axon that is not covered by myelin
Term
saltatory conduction
Definition
propogation of an action potential at successive nodes of ranvier; saltatory means "jumping" or "dancing"
Term
autoimmune disease
Definition
illness resulting from the loss of the immune system's ability to discriminate between foreign pathogens in the body and the body itself
Term
excitatory postsynaptic potential
Definition
brief depolarization of a neuron membrane in response to stimulation, making the neuron more likely to produce an action potential
Term
inhibitory postsynaptic potential
Definition
brief hyperpolarization of a neuron membrane in response to stimulation, making the neuron less likely to produce an action potential
Term
temporal summation
Definition
graded potentials that occur at approximately the same time on a membrane are summated
Term
spatial summation
Definition
graded potentials that occur at approximately the same location and time on a membrane are summated
Term
back propogation
Definition
reverse movement of an action potential into the dendritic field of a neuron; postulated to play a role in plastic changes that underlie learning
Term
stretch-sensitive channel
Definition
ion channel on a tactile sensory neuron that activates in response to stretching of the membrane, initating a nerve impulse
Term
end plate
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
Term
transmitter-sensitive channel
Definition
receptor complex that has both a receptor site for a chemical and a pore through which ions can flow
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