Nervous system facts for kids

Illustration of how pain travels to the brain, from René Descartes's Treatise of Man

The nervous system is the part of your body that helps you sense the world, think, learn, remember, and control your movements and body functions. It's made of your brain, spinal cord, and all the nerves that reach every corner of your body. It is like your body's super-fast communication network! It helps you know what's happening around you and inside you, and it tells your body how to react.

It's made of special cells that send messages using tiny electrical and chemical signals. These messages travel super fast, sometimes over 100 meters per second! The nervous system works closely with another system called the endocrine system, which uses hormones (chemical messengers) to help control things in your body, but the nervous system is much faster and more direct.

Main parts

Major elements in synaptic transmission. An electrochemical wave called an action potential travels along the axon of a neuron. When the wave reaches a synapse, it provokes release of a small amount of neurotransmitter molecules, which bind to chemical receptor molecules in the membrane of the target cell.

The nervous system in animals with backbones (like humans!) has two main parts:

• The Central Nervous System (CNS): This is the main control center. It's made up of:

1. The Brain: This is like the supercomputer! It's inside your head and protected by your skull. It processes information, makes decisions, and controls everything from breathing to thinking.
2. The Spinal Cord: This is a long bundle of nerves that runs down your back, protected by your backbone (vertebrae). It carries messages between your brain and the rest of your body. It also handles some quick reactions called reflexes all by itself!

• The Peripheral Nervous System (PNS): This is like the network of wires that connects the CNS to the rest of your body. It's made up of all the nerves that branch out from the brain and spinal cord. Nerves are like cables made of bundles of long fibers from nerve cells. They carry messages back and forth. Some nerves carry messages from your body to the CNS (these are called sensory nerves – they tell your brain what you see, hear, feel, etc.). Other nerves carry messages from the CNS to your muscles and glands (these are called motor nerves – they tell your muscles to move or your glands to release chemicals).

The PNS also has different jobs. One part, called the autonomic nervous system, controls things you don't have to think about, like your heart beating, your stomach digesting food, and breathing.

This part has two teams:

• The sympathetic nervous system gets you ready for action (like when you're excited or need to run fast).
• The parasympathetic nervous system helps you calm down and rest.

Amazing cells

The nervous system is made of special tissue, and the most important cells are:

Neurons

These are the main messengers! They have a unique shape that helps them send and receive signals.

1. They have a main body and long fibers called axons that send signals away.
2. They also have branches called dendrites that receive signals from other neurons.
3. Neurons talk to each other at tiny gaps called synapses. At synapses, they release chemicals called neurotransmitters that pass the message along. This is how information travels through the nervous system!

Glial cells

These cells are like the helpers and supporters for the neurons. The word "glia" comes from the Greek word for "glue," and they do help hold things together!

1. They provide support and food for neurons.
2. They help clean up waste and protect neurons.
3. A very important job is making a fatty covering called myelin around axons. Myelin is like insulation on a wire; it helps the signals travel much faster and more efficiently!

How the nervous system works

The nervous system's main job is to control your body. It does this in a few steps:

• Sensing: Special parts of your body (like your eyes, ears, skin, and tongue) have sensory receptors that detect things in the environment (like light, sound, touch, taste, and smell).
• Sending Messages: Sensory neurons send signals about what is detected to the CNS.
• Processing: The brain and spinal cord process this information. They figure out what it means and decide what to do.
• Responding: The CNS sends signals through motor nerves to muscles or glands, telling them to act (like moving your hand, speaking, or making your heart beat faster).

This happens incredibly fast. A simple example is a reflex, like quickly pulling your hand away from something hot. Sensory neurons in your skin detect the heat and send a signal to your spinal cord. The spinal cord quickly sends a signal back through motor neurons to your arm muscles, telling them to contract and pull your hand away – all before your brain even fully registers the pain!

More complex actions, like deciding what to eat or solving a math problem, involve many parts of your brain working together.

Development

Your nervous system starts forming very early, even before you are born. In the beginning, a flat strip of cells on your back folds up to make a tube. This tube will become your brain and spinal cord. Other cells nearby will become the nerves of your peripheral nervous system. Scientists are still learning exactly how all these cells know where to go and what to become!

Interesting facts about the nervous system

• Scientists think the first simple nervous systems appeared in tiny worm-like creatures a very, very long time ago, maybe 550 to 600 million years ago.
• The nervous system can react in 1/100 of a second to a stimulus, like a pain signal.
• Not all animals have a nervous system like ours. Simple animals like sponges don't have a nervous system at all.
• Jellyfish have a simple "nerve net" spread throughout their body.
• Worms have a more organized system with nerve cords and a simple "brain" (ganglion) at the head.
• Insects and other arthropods have a brain and nerve cords along their belly, with smaller control centers (ganglia) in each body section.
• There are hundreds of different types of neurons, each with a special job.
• Mirror neurons fire both when you do an action and when you watch someone else do the same action. Some scientists think these might help us understand what others are doing or learn by copying them.

Related pages

• Central nervous system
• Brain
• Spinal cord
• Peripheral nervous system
• Autonomic nervous system
• Sympathetic nervous system
• Parasympathetic nervous system
• Somatic nervous system

Images for kids

• 

  Earthworm nervous system. Top: side view of the front of the worm. Bottom: nervous system in isolation, viewed from above

• 

  Layers protecting the brain and spinal cord.

See also

In Spanish: Sistema nervioso para niños