Page 67 - The Miracle of Electricity in the Body

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WHAT HAPPENS WHEN YOU TREAD ON A NAIL?
To better understand how a nerve signal takes place, consider the pain caused
when you tread on a nail. Because of the object trodden on, the nerve endings
of the cells in your foot contract, leading to the opening of the channels in the
cell membranes. Sodium ions are permitted to enter the cell, leading to a
greater negative charge in the fluid remaining outside the cell. When this dif-
ference reaches a critical point, a signal is sent.
Subsequently, in order to restore to its former state this electrical differential
between the inside and outside of the cell, the sodium channel is neutralized.
In the cell membranes, proteins known as sodium-potassium pumps re-estab-
lish the ion balance. For every sodium ion that leaves the interior of the cell, a
potassium ion is pumped in the opposite direction.
As a result of these reactions, the information regarding a nail having penetrat-
ed the skin is transmitted upwards by means of the nerves. Reaching the spinal
column, this information is passed on to other nerve cells. Some nerve cells
carry this information by means of axons to the region
of the brain that records sensations of pain Brain
Others, together with motor nerve cells, send
the signal directly to the leg muscles, instruct-
ing them to contract and withdraw the foot.
In order for this event to happen, which
takes place within a second or two, a large
number of systems come into play. Each
component necessary for these systems
to function is a complex mechanism in its
own right. As you have seen, we live
thanks to systems built on exact calcula- Cross-sec-
tions and sensitive planning. All these are tion of spinal
cord
miracles of Creation that remind us of
our Lord, Who pervades and enfolds all
places, and that enable us to properly ap-
preciate His knowledge.
Muscular
system
Sensory
system