Download Getting to Know: Nervous

Getting to Know: Nervous
The nervous system serves as the bridge between the outside world and your body. All of the five senses—sight, hearing, smell, taste, and touch—are connected to your nervous system. Any information that your body perceives then goes straight to the brain for processing.
Of course, if all our nervous system did was to
process outside information, we would never know how to respond to When we feel pain, it is our nervous
any of it. The nervous system
system telling us that something is wrong.
therefore has to operate in two directions: body-to­
brain and brain-to-body. If you touch something that is very hot, your
brain receives the message and sends back a message instructing your
hand to jerk away. In this way, your nervous system helps your body to
respond appropriately to the world around you.
What is the nervous system?
The nervous system works alongside the endocrine system to control
your body. Although the endocrine system controls functions like body
temperature and blood pressure, the nervous system is responsible for
your ability to sense, think, and react. The functions of the nervous
system are to receive and respond to stimuli, to transmit impulses to
the body, and to help maintain bodily homeostasis.
The nervous
system includes
the brain, spinal cord,
and nerve cells.
The nervous system is divided into two parts, the central nervous system
and the peripheral nervous system. The central nervous system consists
of the brain and the spinal cord and serves as the body’s control center.
The peripheral nervous system contains the nerve cells that extend to
the rest of the body. The peripheral system’s job is to carry impulses
between the body and the central system, causing the voluntary (or
chosen) and involuntary (or automatic) reactions you experience.
Misconception 1: I thought the nervous system only involved the brain. Is this true?
The brain is the most important part of the nervous system, but the nervous system
actually extends throughout the entire body.
Concept: Nervous
Getting to Know
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How does the nervous system work?
The nervous system controls the body through electrical impulses that are transferred
through cells called neurons. Messages race along the neurons from the body to the brain
and back again. Receptor cells in the body tell the brain what it is experiencing, and the brain
sends back a message telling the body how to react. The entire process takes only a fraction
of a second.
What are neurons?
Neurons, or nerve cells, are special cells that make
up the body’s nervous system. They are found throughout the nervous system. Types of neurons
include sensory, interneuron, and motor neurons.
These cells serve different functions within the nervous system. Sensory nerve cells carry messages from the body to the brain, whereas motor nerve cells carry the signals from the brain to the organs
and tissues. Interneurons serve as the link between sensory and motor nerve cells. Neurons are made up of a cell body surrounded
by branching fibers called dendrites. There is also a single long fiber branching off of the neuron
called the axon. Neurons vary in size, but some
have axons that stretch for more than one meter
in the body! The nerve cells do not touch each
other but are separated by spaces called synapses.
Neurons contain branching fibers called
dendrites and one long fiber called the
axon.
Electrical impulses travel along the axon and across the synapse and are then picked up by the
dendrites of a nearby nerve cell. In this way, the electrical impulses are passed swiftly from one
cell to another. Your nervous system is constantly using these impulses to pass signals back
and forth between your body and brain.
Misconception 2: When I feel nervous, am I experiencing the effects of the
nervous system?
When people say they are “nervous,” it means that they feel worried or uncertain. This is
actually caused by a different series of reactions in the body and does not have anything
to do with the body’s true nervous system.
In this concept, you will learn more about how the nervous system helps you sense and
respond to your environment.
Concept: Nervous
Getting to Know
www.discoveryeducation.com
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© Discovery Education. All rights reserved.
Discovery Education is a subsidiary
of Discovery Communications, LLC.