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Neurons
transmit nerve impulse as action potentials
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Information travels which way along neurons
dendrite> cell body> axon
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Grade potentials (type of signal)
small, localized changes in membrane potential due to, and in proportion to, a stimulus. Initiates an action potential in a neuron!
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Action potentials (type of signal)
neuron sends an impulse, an all-or-nothing phenomenon
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Temporal summations
rapid-fire of stimulating neuron, makes depolarization more likely
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Spatial summation
neuron is stimulated by many other neurons at once
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Ligand-gated channels
short-lived, localized changes in membrane potential are due to these
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post-synaptic potential
Graded potential propogated due to stimulus from another neuron
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Action potential
counterpart to the resting potential
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Depolarization
inside of membrane becomes less negative
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Phases of an action potential
- depolarization
- repolarization
- hyperpolarizaton
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repolarization
membrane returns to resting membrane potential
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hyperpolarization
inside of the membrane becomes more negative than resting potential
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1st Step of the action potential
neurotransmitter bids to ligand gated channel in neuron
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2nd step of an action potential
binding of ligand causes a graded potential
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3rd step of an action potential
soma becomes more positive as graded potential spreads to neighboring areas of the membrane
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4th step of an action potential
action potential is initiated at the axon hillock
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facilitated neuron
successive depolarizations make postsynaptic neuron more likely to fire
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______ rushes into the cell due to electrochemical gradient leading to depolarization along the axon
Na
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Ways to increase speed of transmission
- increased diameter of neuron
- Insulation by myelin sheath
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electrical synapses
gap junctions connect cells, rar, but found in adult CNS
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Excitatory postsynaptic potential (EPSP)
when neurotransmitter is taken up by the post synaptic neuron this causes EPSP
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synaptic delay
the time needed for the neurotransmitter to be released, diffuse across the synapse, and bind to receptors
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Rate-limiting step of neural transmission
synaptic delay
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