Hey Kids! Do you like reading
books and imagining adventures of heroes
and heroines? Do you enjoy science
experiments and dream of making a new
discovery? Are you interested in rugby or
baseball or in other sports and do you
spend lots of time practicing in order to
become an excellent player? Well Luke
Rickard, age 10, (the boy in the picture
above), lives in Dublin, Ireland and he
loves playing rugby, reading books and
doing science experiments and science
activities at home or in school. In fact he
asked his Mom and his teacher to help him
learn about his brain last week for Science
Week in Ireland and this is what he put
together (ok with help from his mom:)) to
present to his class.
The first thing he discovered was
that all of these activities that he loves
doing involve the use of his nervous system, which is a network of tissue that sends and carries
messages to all the different parts of the body. This system evolved in order for him to sense his
environment and respond precisely to changes within and outside of his body. The central
nervous system (CNS) consists of the brain and spinal cord while as the peripheral nervous
system is made up of those all those other branch-like nerves, big and small, that extend
throughout our bodies right out to our internal organs, limbs, muscles, skin, fingers and toes.
Nerves - Peripheral Nervous System
Nerves are sort of like wires that carry communication signals or impulses around the body.
Inside each nerve is a bundle of nerve fibers. Some nerves are really long, like the ones that go
all the way from your feet to your spinal cord. Nerve cells are called neurons.
There are two main types of nerves: motor nerves and sensory nerves.

Motor nerves - Motor nerves allow the brain to control our muscles. The brain sends
signals over the motor nerves to tell our muscles to expand or contract so we can move.

Sensory nerves - The second type of nerves are called sensory nerves. These nerves carry
signals to the brain to tell it about what is going on in the outside world. They come from
our skin (touch), nose (smell), eyes (sight), tongue (taste), nose (smell), and ears (hear).
In each case, the signals only go in one direction. Motor nerve signals travel from the
brain to the muscle and sensory nerve signals travel from the sense to the brain.
The peripheral nervous system is divided into two parts:
1. The autonomic nervous system located in the base of this brain, or brainstem,
preforms involuntary functions (involuntary means we are not conscious of doing
them) like the beating of our heart, the digesting of our food and breathing.
2. The somatic nervous system, responsible for nearly all voluntary muscle movements
as well as for processing sensory information including hearing, touch and sight.
What is the Organization of the Nervous System?
The nervous system uses chemical messengers called neurotransmitters to relay messages from
one part of the nervous system to the other. They travel from one nerve cell, or neuron, to the next
bringing messages to and from the body to the brain.
The Neuron
Each nerve is made up of many cells called neurons. To learn more about neurons, let's take the
motor neuron for example. Each motor neuron has three important parts: the cell body, dendrites,
and the axon. Dendrites are branches off the main cell body. They talk to dendrites from the cell
next to them over something called a synapse. Axons connect to the muscles and tell them what to
do.
The communication lines in your CNS are called tracts. Tracts make up what are called grey matter
and white matter.
When white matter is mentioned, think of bundles of axons with white myelin sheaths. These
myelinated tracts connect grey matter areas of the brain to each other and carry nerve impulses
between neurons. They function for rapid transmission of stimuli and responses. On the other hand,
gray matter is composed of unmyelinated axons, cell bodies, dendrites and neuroglial cells.
Neuroglial cells are not neurons but supporting cells that protect or provide nourishment to the
neurons. Because it lacks myelin, gray matter has slower transmission compared to white matter.
Both the brain and the spinal cord are made up of gray and white matter.
In your Journals, answer the following questions. Write the questions and the answers:
1. According to paragraph 2, what is the nervous system?
2. What makes up the Central Nervous System (CNS)?
3. What makes ups the Peripheral Nervous System?
4. Explain the difference in the two types of nerves.
5. Explain the difference in the two parts of the Peripheral Nervous System.
6. Define a Neurotransmitter.
7. Draw and label the Neuron.
8. Draw and label the brain and spinal cord.
9. What is white matter?
10. What is grey matter?
11. What is a neuroglial cell?