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- Neurons are specialized cells that transmit information.
- Neurons have dendrites at one end that receive messages from other neurons.
- At the opposite end, neurons have an axon that carries messages to other neurons.
- Axons end in small bulges called terminal buttons that send messages to other neurons.
- The myelin sheath covers many axons and increases the velocity of the impulse.
- Neurons follow an all-or-none law: they are either on or off, with nothing in between.
- Before a neuron is triggered it is in its resting state.
- It has a negative electrical charge of about -70 millivolts.
- When a message is sent, an electrical nerve impulse, known as an action potential, travels along the axon of the neuron.
- Axons with small diameters carry impulses at about 2 miles per hour; longer and thicker ones can average speeds of more than 225 miles per hour.
- Some neurons are capable of firing as many as a thousand times per second; others fire at much slower rates.
- After an action potential has passed through a section of the axon, that area cannot immediately fire again.
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