31 Chapter 1 Learning About Children
This interaction can also be
observed in the developing brain.
Genes and environment work
together to shape a child’s brain.
The effects of each are unique.
Brain Development
The command center of the
body—the brain—fascinates
scientists. People who study and
work with children are also often
curious about how the brain
grows and changes in childhood.
Until recently, the brain was
mostly a mystery. However,
in recent years, scientists have
learned much more about brain
development. Much of this
knowledge is gained from the use
of high technology and advances
in biochemistry. An abundance of
brain research is now in progress.
Although many questions have
been answered, many more
remain for scientists to unravel.
Basic Wiring Occurs
The brain is responsible for
controlling most body functions.
These include operation of the body
systems, movements, thinking,
memory, and feelings. Brain cells
called neurons control these tasks.
The neurons send and receive
electrical impulses throughout
the brain. These impulses are like
messages that tell body parts or
systems what to do.
Electrical impulses can pass
within a single brain cell or between
two brain cells. Special chemicals
send both types of impulses (within
one cell or between two cells). When
a message must travel between
cells, however, it needs a pathway
along which to travel. For this
“talk” between neurons, the brain
builds a web of fi bers to serve as
links between cells. Think of these
fi bers as microscopic cables that
carry brain signals. This network of
fi bers is called the brain’s wiring.
Each neuron can develop
two types of cables, 1-6. Longer,
heavier cables called axons send
signals. Each cell can have only
one axon. This axon transmits
all the signals from this neuron
to other neurons. Short, bushy
cables called dendrites receive
signals. One cell can have as
many as 15,000 dendrites. The
axon from one neuron, however,
does not touch the dendrite of
another neuron. Instead, there is
a tiny gap between them, which
is called a synapse. As the signal
leaves the axon, it jumps the
synapse to travel to the dendrite.
The brain’s complex wiring
allows one axon to send signals to
many dendrites simultaneously.
Cell body
Axon
Dendrites
Synapse
Wiring of Brain Cell
1-6
Brain cells “communicate” with one another
by sending messages from the axons of one
neuron across the synapse to the dendrites
of another neuron.