Test 2 (Chapter 4) Flashcards
Microelectrodes
Extremely fine recording electrodes, which are used for intracellular recording
Membrane potential
The difference in electrical charge between the inside and outside of the cell
Resting potential
The steady membrane potential of a neuron at rest, usually about -70 mV
Ions
Positively or negatively charged particles
Concentration gradients
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Electrostatic pressure
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Ion channels
Pores in neural membranes through which specific ions pass
Sodium-potassium pump
Active transport mechanisms that pump Na+ ions out of neurons and K+ ions in
Transporters
Mechanisms in the membrane of a cell that actively transport ions or molecules across the membrane
Depolarize
To decrease the resting membrane potential
Hyperpolarize
To increase the resting membrane potential
Excitatory postsynaptic potential (EPSP)
Graded post-synaptic depolarizations, which increase the likelihood that an action potential will be generated
Inhibitory postsynaptic potential (IPSP)
Graded post-synaptic hyperpolarizations, which decrease the likelihood that an action potential will be generated
Graded responses
Responses whose magnitude is indicative of the magnitude of the stimuli that induce them
Axon hillock
The conical structure at the junction between the axon and cell body
Threshold of excitation
The level of depolarization necessary to generate an action potential, usually about -65 mV
Action potential
A massive momentary reversal of a neurons membrane potential from about -70 mV to about +50 mV
All or none responses
Responses that are not graded, that either occur to their full extent or not at all
Integration
Adding or combining a number of individual signals into one overall signal
Spatial summation
The integration of signals that occur at different sites on the neurons membrane
Temporal summation
The integration of neural signals that occur at different times at the same synapse
Voltage-activated ion channels
Ion channels that open and close in response to changes in the level of the membrane potential
Rising phase
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Repolarization
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Absolute refractor period
A brief period (typically 1 to 2 milliseconds) after the initiation of an action potential during which it is impossible to elicit another action potential in the same neuron
Relative refractory period
A period after the absolute refractory period during which a higher than normal amount of stimulation is necessary to make a neuron fire
Nondecremental
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Antidromic conduction
Axonal conduction opposite to the normal direction; conduction from axon terminals back toward the cell body
Orthodromic conduction
Axonal conduction in the normal direction- from the cell body toward the terminal buttons
Nodes of Ranvier
The gaps between adjacent myelin segments on an axon
Saltatory conduction
Conduction of an action potential from one node of Ranvier to the next along a myelinated axon
Hodgkin-Huxley Model
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Axodendritic synapses
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Dendritic spines
Tiny nodules of various shapes that are located on the surfaces of many dendrites and are the site of most excitatory synapses in the mature mammalian brain
Axosomatic synapses
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Dendrite deistic synapses
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Axoaxonic spines
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Presynaptic facilitation
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Presynaptic inhibition
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