BIOL 3322: Chapter 2
15 Cards in this Set
| Front | Back |
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Glia
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Support cells in nervous system
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astrocytes
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star-shaped cells help synchronize activity of the axon, help them send messages in waves, remove waste
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blood brain barrier
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tight junctions between the cells that compose blood vessels in the brain, providing a barrier to the entry of an array of substances, including toxins into the brain
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Active transport
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protein-mediated process that expends energy to pump chemicals from the blood into the brain
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electrical gradiant
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difference in electrical charge between the inside and outside
of the cell
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hyperpolarization
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an increase in membrane potential (the interior of the neuron becomes even more negative).
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depolarization
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reduce its polarization toward zero
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Excitation threshold
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The voltage difference between a neuron's interior and exterior that, if exceeded, causes the neuron to fire.
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action potential
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a rapid depolarization and slight reversal of the usual polarization
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voltage-gated channels
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membrane channels whose
permeability depends on the voltage difference across the
membrane
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all-or-none law
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amplitude and velocity of an action potential are independent
of the intensity of the stimulus that initiated it
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AXON HILLOCK
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in a motor neuron, an action potential begins on a swelling where the axon exits the soma.
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propagation of the action potential
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transmission of an action potential down an axon
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saltatory conduction
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jumping of action potentials from node to node
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graded potentials
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membrane potentials that vary
in magnitude without following the all-or-none law.
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BIOL 3322: Chapter 2