Chapter 15 Section 1: How the Nervous System Works

nerve

A bundle of nerve fibers.

neurons

A cell that carries information through the nervous system.

stimulus

A change or signal in an organism's surroundings that causes the organism to react.

nerve impulse

A message carried by a neuron.

What is the structure of a neuron?

A neuron has a large cell body that contains the nucleus, threadlike extensions called dendrites, and an axon.

interneuron

A neuron that carries nerve impulses from one neuron to another.

sensory neurons

A neuron that picks up stimuli from the internal or external environment and converts each stimulus into a nerve impulse.

motor neuron

A neuron that sends an impulse to a muscle or gland, causing the muscle or gland to react.

dendrites

A threadlike extension of a neuron that carries nerve impulses away from the cell body.

response

An action or change in behavior that occurs in reaction to a stimulus.

How do nerve impulses travel from one neuron to another?

For a nerve impulse to be carried along at a synapse, it must cross the gap between the axon and the next structure. The axon tips release chemicals that carry the impulse across the gap.

synapse

The junction where one neuron can transfer an impulse to another structure.

What are the functions of the nervous system?

The nervous system receives information about what is happening both inside and outside your body. It also directs the way in which your body responds to this information. In addition, your nervous system helps maintain homeostasis.

What kinds of neurons are found in the body?

Three kinds of neurons are found in the body--sensory neurons, interneurons, and motor neurons.