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9 Cards in this Set
- Front
- Back
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What happens during the rising phase of an action potential in neurons? |
Sodium flows into the neurons through voltage-gated ion channels. |
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What is the resting potential in neurons ordinarily nearest (which ion)? |
The equilibrium potential for K+ |
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What is the difference between reversal potential and equilibrium potential? |
Essentially equilibrium potential only involves one ion. Reversal potential (Nernst potential) is experimentally determined potential involving all ions. |
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Generation of an action potential in a neuron depends on what? |
Depolarization caused by opening Na+ channels. |
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52 year old woman. Slowly progressive weakness, dry mouth, constipation, light headed when standing, neurological examination = generalized weakness of all extremities. Small cell carcinoma of lung.
Where would you localize lesion? |
Diffuse nerve-muscle junction Lambert-Eaton syndrome |
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What is the underlying pathophysiology of the previous case (Lambert-Eaton syndrome)? |
Antibody blockade of presynaptic nerve-muscle junction Ca2+ channels. |
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6 year old boy, recurrent attacks of weakness then recovers fully, physical activity like riding bike or running race, attacks after eating bananas, general and neurological exam normal.
From the above information, where would you localize the lesion? |
Diffuse muscle (myopathy) |
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What is the diagnosis? |
Periodic paralysis (a type of channelopathy) |
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What is the pathophysiology? |
Point mutation of muscle cell membrane Na+ or K+ channels |
