What is the function of the myelin sheath and nodes of Ranvier?
To create Saltatory conduction (speed up transmission)
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How are neurons separated?
a narrow fluid gap called the synaptic cleft
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What does the depolarisation of the pre synaptic nerve cause?
Vesicles of neurotransmitter move to the pre synaptic membrane and fuse with it, releasing the neurotransmitter into the synaptic cleft by exocytosis
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How does neurotransmitter cross the synapse?
It diffuses across the cleft, binding to receptors on the post-synaptic nerve
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What type of receptors are on the post synaptic membrane?
Transmitter-gated sodium channels
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What happens when transmitter binds to the receptors?
Sodium ions diffuse into the post-synaptic neuron, causing deploarisation
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How is continuous synaptic transmission prevented?
Neurotransmitter left in the synaptic cleft is broken down and re absorbed into the pre-synaptic nerve
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What is a cholinergic synapse?
A synapse which uses the neurotransmitter acetylcholine
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How is acetylcholine prevented from causing continuous synaptic transmission?
broken down into acetyl groups and choline by the enzyme cholinesterase
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How do neonicotinoid pesticides kill insects?
It binds (and cannot be broken down, so remains bound) to acetylcholine receptors, preventing acetylcholine from binding
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What is the resting potential?
The voltage across the plasma membrane of a neuron when it is not conducting a nerve impulse
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What mV is the resting potential, and why?
-70mV, because of unequal exchange of Na+ and K+ at sodium/potassium pumps
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During resting potential, what is the formation of the K+ and Na+ channels?
both closed
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What is the action potential?
brief depolarisation caused by changes in currents
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What is the action potential threshold?
-50mV
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What is the voltage of an action potential?
+40mV
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During an action potential, what happens to the voltage gated Na+ and K+ channels?
They open, so Na+ enters and K+ leaves, along the electrochemical gradient created by the resting potential
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What is repolarisation?
The restoration of the resting potential
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What is the formation of the K+ and Na+ channels during repolarisation?
K+ channels open, Na+ channels closed
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What is hyperpolarisation?
a brief lowering of the voltage to -75mV (below the polarised level), caused by a delay in the activation of the sodium potassium pumps and closing of Na+ and K+ channels
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Other cards in this set
Card 2
Front
How are neurons separated?
Back
a narrow fluid gap called the synaptic cleft
Card 3
Front
What does the depolarisation of the pre synaptic nerve cause?
Back
Card 4
Front
How does neurotransmitter cross the synapse?
Back
Card 5
Front
What type of receptors are on the post synaptic membrane?
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