Term
| response in a given neuron is always |
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Definition
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Definition
-measure of PE between two points
-inside compared to outside of cell |
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Definition
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| a small inequality in charge distribution causes a |
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Definition
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Definition
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Definition
| -balance concentration and charge |
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Term
| why little intracellular Cl-? |
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Definition
| -negatively charged macromolecules |
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Term
| equilibrium membrane potential |
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Definition
-the point where the electric field counteracts the F due to diffusion
-determined by Nerst equation |
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Term
| Na+ equilibrium membrane potential |
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Definition
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Definition
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Term
| intra and extra neuronal ion concentrations determined by |
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Definition
-Na/K ATPase
-flow thru ion SELECTIVE channels |
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Term
| constitutively active (non-gated channels) |
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Definition
-leak channels
-always open
-more permeable to K+ (100x) |
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Term
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Definition
-pumps 3 Na OUT
-pumps 2 K IN |
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Term
| voltage gated sodium channels |
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Definition
-changes in voltage increase the likelihood that channel will open
-takes a long time to get out of inactive state |
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Definition
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Term
| Resting membrane potential (Vm) |
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Definition
-no net current across the cell
-all gated channels closed
-value determined by ion concentrations and permeability |
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Term
| Why does cell need all the Na to stay out? |
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Definition
-Na gradient is used to bringing in other things (glucose)
-balance osmolarity |
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Term
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Definition
| makes membrane potential more + |
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Definition
| makes membrane potential more negative towards resting membrane potential |
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Definition
| -makes membrane potential more negative past membrane potential |
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Definition
-happens in all cells
-moves in both directions
-stronger the stimulus, the greater the potential, the farther the current flows
-do not have voltage gated Na channel? |
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Term
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Definition
-all or none
-when K leak cannot compensate for Na
-only in neurons and muscle
-in a given cell, all APs are the same amplitude
-greater stimuli do not lead to bigger action potentials |
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Term
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Definition
-positive feedback loop
-opening of Na channels
-increased Na permeability
-increased flow of Na IN the cell
-decreased membrane potential
-opening of Na channels |
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Term
| Why does AP stop at peak? |
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Definition
-voltage gated Na channels inactivate
-cannot go past equilibrium membrane potential |
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Term
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Definition
| -no AP can be generated because Na permeability is LOW |
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Term
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Definition
| AP can be generated if a large depolarizing stimulus |
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Term
| Resting membrane potential restored by Na/K ATPase? |
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Definition
| NO! Regulates concentration not voltage! |
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Term
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Definition
-more K+ flows out
-harder to produce AP |
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Term
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Definition
-generated anew at each subsequent patch of membrane
-does NOT decrease in strength as it goes along |
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Term
| how the CNS determines whether a stimulus is strong or weak? |
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Definition
| NUMBER of APs not amplitude |
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Term
| why AP is generated at axon hillock? |
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Definition
| high concentration of voltage gated ion channels |
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Term
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Definition
-gets rid of leak current?
-most voltage gated channels in nodes
-can pass thru damaged nodes |
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Term
| another way to increase propagation speed |
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Definition
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Term
| multiple sclerosis caused by |
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Definition
| myelin sheath destruction |
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