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15 Cards in this Set
- Front
- Back
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what is EPSP?
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excitatory post-synaptic potential
(a signal which causes depolarization of the post-synaptic membrane) |
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what is IPSP?
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inhibitory post-synaptic potential
(a signal which causes hyperpolarization of the post-synaptic membrane) |
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where do action potentials start?
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axon hillock
initial segment |
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what causes action potentials to start at the initial segment?
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there is a high density of Na channels their
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what is depolarization?
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membrane potential change making it more positive (or less negative)
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what is hyperpolarization?
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any membrane potential change making it more negative (or less positive)
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what is the all or none rule of action potentials?
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action potentials have a constant shape in a defined cell area, independent of stimulation and frequency
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how does permeability change during an action potential?
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first, sodium permeability increases, followed by an increase in potassium permeability
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what is the effect of tetrodotoxin?
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Na channel inhibitor
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what is the effect of lidocaine?
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Na channel inhibitor
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what is the effect of tetra-ethyl ammonium (TEA)?
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K channel inhibitor
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what is an absolute refractory period?
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brief period in which it is impossible to produce another action potential
(caused by Na channels, which are closed) |
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what is the physiological effect of the absolute refractory period?
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limits the rate of firing action potentials
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what is a relative refractory period?
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a period in which the neuron can fire another action potential, but only when a more intense stimulus is provided
(caused because not enough Na channels are opened to initiate a second AP, and because K channels are open causing hyperpolarization) |
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what are the important features to membranes as capacitors?
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capacitance is very high because they are so thin
only a small number of ions is required to produce a potential difference only a small number of ions must be transported to change the potential across a membrane |
