Biology / Unit 10: Human Body Systems
10.4 The Nervous System
Notes
The nervous system sends fast electrical signals to control the body.
- The central nervous system (CNS) is the brain and spinal cord. The peripheral nervous system (PNS) is all the nerves branching out.
- A neuron has dendrites (receive signals), a cell body, and an axon (sends signals).
- Signals travel along an axon as an electrical impulse. At a synapse, chemicals called neurotransmitters carry the signal to the next cell.
- Sensory neurons carry information to the CNS; motor neurons carry commands to muscles.
- A reflex is a fast, automatic response that goes through the spinal cord before the brain notices (pulling your hand off a hot stove).
Practice
Which part of a neuron receives signals from other neurons?
Dendrites are branch-like extensions that pick up signals.
You touch a hot pan and pull your hand away before you feel pain. This fast response is a:
Reflexes are routed through the spinal cord for speed.
How does a signal cross the synapse between two neurons?
Neurotransmitters are chemical messengers that cross the gap.
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