Term
| what do the sodium and potassium gates look like at rest? |
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Definition
the ungated potassium channel is always open
the potassium gate is closed
the sodium activation gate is closed
the sodium inactivate gate is open
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Term
| what do the Na and K channels look like when threshold is reached? |
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Definition
the potassium channel is slowly opening
both the sodium channels are opened
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Term
| what do the gates look like when they are repolarizing back to threshold? |
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Definition
the potassium channel is open all the way
the Na activation gate is slowly closing
the Na inactivation gate is closed
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Term
what do the gates look like during afterhyperpolarization?
what is afterhyperpolarization? |
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Definition
afterhyperpolarization: membrane potential goes below threshold
K channel is still open and very permeable
Na activation gate closes
Na inactivation gate opens
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Term
| how does an action potential move from site of impulse? |
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Definition
| negative charges in the membrane cause postive charges to move out |
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Term
| what direction do the charges move after initial impulse and what are the directions called? |
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Definition
towards the axon terminal-orthodontic
towards the cell body-antidromic
"backwards" |
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Term
| why doesn't the action potential get weaker by the time it travels all the way to it's destination? |
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Definition
| action potentials are regenerated as it moves along the axon via voltage gated Na and K channels |
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Term
| how does a message get passed along to the terminal if they can travel antidromically? |
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Definition
| - if an action potential tries to go to a previous node of ranvier, they are inactivated and in absolute refractory period. |
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Term
| when does the relative refractory period occur? |
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Definition
when it lost enough charge to be repolarized
action potential generation is unlikely but not impossible |
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