Nervous System

Read Pages 611 & 618-620 in your book!

It is a network of nerve cells in the brain, spinal cord, and throughout the body which helps one part of the body communicate with another. The nervous system acts like a computer or telephone network.

Central Nervous System (CNS): All nerves in the brain & spinal cord (runs from brain to tailbone).

Peripheral Nervous System (PNS): All nerves branching away from brain & spinal cord. Peripheral means away from middle.

Neuron: One nerve cell.

Parts of the PNS:

1. Sensory Neuron: Neuron going from sense organ to the spinal cord or brain. It brings information to the central nervous system.

Examples:

pain receptor (skin)------------->spinal cord

heat receptor (skin)------------->spinal cord

sight receptor (eye)--------------->brain

taste receptor (tongue)-------------->brain

2. Motor Neuron: Neuron going from brain or spinal cord to a muscle or gland. They carry messages from CNS telling a body part to do something.

Reflex: A process the body uses to protect itself where sensory input gets a response from central nervous system in shortest time possible. It often does not involve the brain. A reflex follows this path:

sense organ---->sensory nerve---->spinal cord (or brain)---->motor nerve---->muscle (or gland)