Page 58 - The Miracle of Electricity in the Body

56 THE MIRACLE OF ELECTRICITY IN THE BODY

THE DOMINO SEQUENCE OF PROCESSES WITHIN THE

NERVE CELLS
How does information to the effect that your shoes are hurting your
feet reach the brain? How can you perceive discomfort in your feet at the
same intensity in your brain, despite the distance of several feet between
them? Under normal conditions this signal should decrease in propor-
tion to the distance involved. However, there is a special system in your
body to overcome this.
The signals that set out from the pain-sensitive cells are carried
along thanks to the ion movements taking place along the nerve cells. In
this way, the signal travels with no loss of energy, and each transfer ac-
quires new energy in each new region of the cell membrane.
The way the nerve signal is transmitted along the axon can be com-
pared to the chain reaction that takes place when dominoes are lined up
next to one another. When you push over the first domino, all the others
—if set out at specific distances—will fall over in turn. When the first one
falls over, a chain reaction ensues: consecutive tiles topple over until
none remain standing. A similar chain reaction can be seen in the trans-
mission of signals among neurons:

Signal Transmission Actions Swifter than Thought
The nervous system’s con- Some nerve cells are connect-
nections reach everywhere ed to the brain, and others are
in the body. Some functions in direct contact with other
perform automatically, with- nerves that set the muscles in
out our conscious control, motion.
such as our heartbeat and
digestion. Other nerves go
into action when we decide
to do something, like
clenching our fist.

Passing of signals Muscle
Muscle cell cell fibers
Signals body
passing over
nerve
fibers
Sense cell
body
Myelin sheath
Connection with
muscles