Neuroscience basics

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  • Created by: Jess
  • Created on: 14-05-14 12:43
What is the equilibrium potential?
The membrane potential at which the electrical gradient is matched by the concentration gradient. No net ion movement.
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What is the formula for the Nernst Equation?
Ea = 58/z x log([A]o/[A]i)
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Why is the resting membrane potential slightly positive to Ek?
The membrane is not entirely selective for K only.
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What determines the membrane potential?
The permeability of the membrane to ions. The membrane potential moves twoards the equilibrium potential of the dominant ion at the time.
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Why are there permeability changes during an action potential?
Due to volatge sensitive ion channels opening and closing.
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What causes the rising phase of the action potential?
Sodium ions entering through sodium channels. The AP peaks at ENa.
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What are the roles of Na and K ions during the action potential?
Na ions depolarise and K ions repolarise the membrane.
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Describe the positive feedback mechanism of the AP upstroke.
Na channels open due to depolarisation leading to Na influx and further depolarisation. This positive feedback mechanism makes it very fast.
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Describe the negative feedback mechanism of AP repolarisation.
Depolarisation causes K channels to open leading to K efflux carrying positive charge out of the cell causing repolarisation. This process is much slower than the AP upstroke.
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What is the voltage clamp technique?
A way of controlling membrane potential and measuring the movement of charged ions across the membrane as electric current.
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What are the main features of the voltage clamp technique?
A feedback amplifier supplies current to rapidly return membrane potential to a certain level (the command potential). The supplied curren compensates for (and is therefore a measure of) membrane currents.
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What are the main methods for removing Na current?
Pharmacological agents e.g. tetrodotoxin, replacement with a non permeable ion or changing ENa to 0 so there is no net movement of sodium.
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What is the formula for the conductance of sodium?
GNa = INa / (Vm-ENa)
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What shapes the AP?
Alterations in the conductance of the membrane to ions with time.
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Card 2

Front

What is the formula for the Nernst Equation?

Back

Ea = 58/z x log([A]o/[A]i)

Card 3

Front

Why is the resting membrane potential slightly positive to Ek?

Back

Preview of the front of card 3

Card 4

Front

What determines the membrane potential?

Back

Preview of the front of card 4

Card 5

Front

Why are there permeability changes during an action potential?

Back

Preview of the front of card 5
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