Psychology / Unit 2: The Brain and Behavior
2.1 Neurons
Notes
A neuron is a nerve cell that sends and receives messages.
- Dendrites receive signals. The cell body (soma) contains the nucleus. The axon carries the signal away. Axon terminals release chemical messengers.
- The myelin sheath is a fatty coating on some axons that speeds up signals.
- An action potential is the electrical impulse that travels down the axon. It follows the all-or-none principle: a neuron either fires fully or not at all.
- Glial cells support, protect and feed neurons.
Practice
Which part of a neuron receives incoming messages from other neurons?
Dendrites are the branching receivers.
What does the myelin sheath do?
Myelin insulates the axon so impulses travel faster.
The all-or-none principle says that a neuron:
The size of an action potential does not change; a neuron fires fully or not at all.
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