Neurons

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What are some typical features of eukaryotes (4)?
Nucleus containing DNA, mitochondria, cytoplasm, an 'excitable' cell membrane.
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What is the mechanism of the Na-K pump?
3 Na+ bind to pump ---> 1 ATP binds to pump ---> ATP phosphorylated, inorganic phosphate remains bound to pump ---> Na+ released outside cell ---> 2 K+ bind to pump ---> Phosphate detaches from pump to regenerate ATP ---> K+ released inside cell.
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What is passive diffusion?
When small molecules are able to pass through the membrane down a concentration gradient without extra help.
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What is active diffusion?
Diffusion that uses protein channels.
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What is osmosis?
The net diffusion of water molecules from an area of high water potential to an area of low water potential through a selectively permeable membrane.
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What are excitable membranes?
Membranes that have voltage-gated Na+ and K+ channels that open and close due to change in potential.
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What is the membrane potential of a neuron at rest?
-70mv.
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What happens when a membrane becomes depolarised?
The voltage-gated channels start to open.
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What happens after Na channels open?
There is an influx of Na+. This causes the inside of the cell to become less negative.
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What happens after the influx of Na+?
K channels open, releasing K+ out of the cell.
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How does an action potential occur?
If the change in membrane potential is great enough to reach the threshold.
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What is the 'all-or-nothing' principle?
Regardless of how strong an impulse is, if it reaches the threshold the effect will not differ in strength. If an impulse doesn't reach the threshold, an action potential will not occur.
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What causes the absolute refractory period?
The temporary inactivation of voltage-gated channels.
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Card 2

Front

What is the mechanism of the Na-K pump?

Back

3 Na+ bind to pump ---> 1 ATP binds to pump ---> ATP phosphorylated, inorganic phosphate remains bound to pump ---> Na+ released outside cell ---> 2 K+ bind to pump ---> Phosphate detaches from pump to regenerate ATP ---> K+ released inside cell.

Card 3

Front

What is passive diffusion?

Back

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Card 4

Front

What is active diffusion?

Back

Preview of the front of card 4

Card 5

Front

What is osmosis?

Back

Preview of the front of card 5
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