Term
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Definition
• Concentration
• Electrostatic |
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Term
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Definition
| created when ion permeability is different for different ions |
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Term
| K+ permeability exists due to |
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Definition
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Term
| ions increased inside a cell |
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Definition
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Term
| ions increased outside a cell |
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Definition
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Term
| two opposing forces that drive ion movement and what they are |
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Definition
• Diffusion causes ions to spread towards a uniform concentration, along a concentration gradient.
• Electrostatic pressure causes ions to flow towards oppositely charged areas. |
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Term
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Definition
determines the membrane potential required to maintain no net flow of a freely permeable ion
• mV=61.5 X log ([ion]out/[ion]in)
• K+=-92 mV assuming 150mM inside vs. 5 mM outside
• Na=+60 mV |
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Term
| 2 types of changes in membrane polarization |
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Definition
• Hyperpolarization is an increase in membrane potential—the interior of the membrane becomes even more negative and farther from zero.
• Depolarization is a decrease in membrane potential—the interior of the cell becomes less negative and closer
to zero. |
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Term
| Na channel properties and states |
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Definition
Sodium channel proteins in neuronal membranes change their shape in response to the amount of charge separation, or the voltage, across the membrane.
The sodium channel has three states:
• Closed • Open
• Inactive
The progression from closed back to closed must go through open and then inactivated. |
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Term
| ion channels and steps of an action potential |
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Definition
1. K+ open, Na closed (resting potential, -60)
2. closed K channel (reaches threshold -40)
3. sodium rushes in, absolute refractory period) -> pos
4. Na channels inactivated, K+ channels open (relative refractory period) (hyperrepolarization)
5. Na channels closed, K channel opened, returns to resting potential |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| blocks voltage gated Na channels, prevents depolarization |
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Term
| 4-AP (aminopyridine) and TEA |
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Definition
| blocks voltage gated K channels, prolongs repolarization |
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