The neuron and the synapse
How a neuron passes a message: the resting and action potentials, conduction along the axon and the role of myelin, the chemical synapse and its neurotransmitters, and what toxins, drugs and diseases change there.
- 45 cards
- 4 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- Concepts
- The steps
- Scenarios
- Understand
A few cards from the deck
Resting potential: what is it?
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The charge difference between the inside and outside of a resting neuron, about −70 mV.
It comes mainly from potassium leak and the sodium-potassium pump.
The action potential: which step comes after "The stimulus reaches threshold"?
- Sodium channels open
- Sodium flows in: depolarisation
- Sodium channels inactivate and potassium channels open
- Potassium flows out: repolarisation
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Sodium channels open
Sodium channels open the rise, potassium channels the fall, and the pump restores the gradients.
Action potential: what is it?
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A brief reversal of the membrane's charge, triggered when the threshold is reached, that travels along the axon.
It follows the all-or-none law: the message's intensity is coded by frequency.
In multiple sclerosis, myelin is destroyed. What happens to the impulse?
- It slows down or gets blocked
- It speeds up
- It changes direction
- Nothing changes
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It slows down or gets blocked
Without insulation, saltatory conduction is lost.
Depolarisation: what is it?
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The rise of membrane potential caused by sodium ions flowing in through opening channels.
It is the rising phase of the action potential.
If the action potential is 'all or none', how does a neuron code a stronger stimulus?
- Through action potentials of greater amplitude
- Through a change in the neurotransmitter released
- Through action potentials that last longer
- Through a higher frequency of action potentials
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Through a higher frequency of action potentials
The number of neurons recruited matters too.