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25 Cards in this Set
- Front
- Back
The membrane potential at which there is no net flux of an ion across the membrane is called that ion's ________.
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equilibrium potential
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The presence of the ________ prevents the dissipation of the concentration gradient for Na+.
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Na+/K+ pump
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Why is the electrical potential of a membrane at rest closest to potassium's equilibrium potential than to sodium's equilibrium potential?
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more potassium channels are open, allowing more potassium to move out of the cell
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As a membrane's permeability to a particular ion increases, membrane potential will move ________ that ion's ________.
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closer to : equilibrium potential
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True/False: The membrane potential of a cell is determined exclusively by that cell's sodium and potassium permeability.
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FALSE
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True/False: The Nernst equation is used to calculate the resting membrane potential.
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FALSE
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Whether a membrane is depolarized to threshold or above, the amplitude of the resulting action potential is the same; in other words, once threshold is reached, the action potential will take place. This concept is known as __________.
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the "all-or-none principle"
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A change in a cell's membrane potential, such that it becomes more positive, is referred to as a ________.
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depolarization
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The depolarization phase of the action potential is generated by a rapid ________.
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opening of sodium channels
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The repolarization phase of action potentials in neurons is due primarily to ________.
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potassium flow out of the cell
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During which of the following states are the majority of voltage-gated sodium channels closed and incapable of opening?
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during the absolute refractory period
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The all-or-none principle, associated with the action potential, states that ________.
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once membrane potential reaches threshold, an action potential will be generated and that action potential will always be the same magnitude
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In order for a neuron to move from the absolute to the relative refractory period, a majority of that neuron's sodium channels must have their ________.
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inactivation gates open
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In myelinated nerve fibers, where do action potentials occur?
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nodes of Ranvier
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True/False: The magnitude of the action potential is dependent upon the extent to which the change in membrane potential is above threshold
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FALSE
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Where in the neuron is an action potential initially generated?
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axon hillock
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The depolarization phase of an action potential results from the opening of which channels?
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voltage-gated Na+ channels
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The repolarization phase of an action potential results from __________.
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the opening of voltage-gated K+ channels
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Hyperpolarization results from __________.
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slow closing of voltage-gated Na+ channels
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What is the magnitude (amplitude) of an action potential?
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100 mV
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The membranes of neurons at rest are very permeable to _____ but only slightly permeable to _____.
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K+; Na+
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During depolarization, which gradient(s) move(s) Na+ into the cell?
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both electrical and chemical gradients
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What is the value for the resting membrane potential for most neurons?
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(-70 mV)
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The Na+–K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped?
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K+ is pumped out of the cell and Na+ is pumped into the cell
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The concentrations of which two ions are highest outside the cell.
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Na+ and Cl-
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