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5 Cards in this Set
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describe the resting potential |
When an impulse is not being transmitted the neurone is said to be polarised (inside of axon in respect to the outside) with the inside of the axon having a potential difference of -70mV. There are more sodium ions in the outside and more potassium ions inside. |
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What happens when a receptor is stimulated above it’s threshold? |
A process called depolarisation begins the transmission of a nerve impulse. During depolarisation the sodium channel proteins open allowing more sodium ions to diffuse in down a concentration gradient. This causes more sodium channels to open so even more sodium diffuses in. |
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What happens after depolarisation? |
After depolarisation the potential difference inside the axon is +40mV. The sodium channels then close and the potassium channels open. This allows more potassium to diffuse out making the inside of the axon less positive |
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What is hyperpolarisation? |
It restores the resting potential of -70mV by using a sodium potassium pump which removes 3 sodium ions and returns 2 potassium ions at a time |
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What is the action potential and why does it only go in one direction? |
The action potential involves a change in the potential across the axon membrane. It only goes in one direction because of hyperpolarisaion and it can only undergo depolarisation again when it is at the resting potential. |
