Page 186 - The Miracle of Hormones

THE MIRACLE OF HORMONES

thought that hundreds of pro-
teins perform a function. This
operation happens serially and
in perfect order, causing partic-
ular ion channels to open on
the cell's membrane. The result
is that the sodium ions that are
taken inside the cell neutralize
the cell that earlier had a nega-
tive electric charge (-70 milli-
volts). The transfer of ions
between the inside and the
outside of the cell creates an
electric signal. The operations
that we have described here in Amessage left on a receptor on
the membrane of a nerve cell
the simplest of terms begin and starts a series of reactions inside
end in less than one thou- the cell similar to a row of falling
dominoes.
sandth of a second.
The signal that is created travels quickly along the axon and initiates
the chemical operations that will pass the message to other cells on the
synapse points on the ends of the terminals. The average speed of the sig-
73
nal along the axon is 120 meters per second. Asimple calculation will
show us that this speed equals 432 kilometers per hour.
The nerve cell that transmitted the message completes its task and re-
turns to its resting state. This restoration happens by the opening and clos-
ing of the sodium and potassium channels within a period of less than one
thousandth of a second. Without a clock produced by means of high tech-
nology, you cannot measure one thousandth of a second. Imagine that you
had such a watch; you still could not coordinate the opening and closing
of the ion channels on one single nerve cell. If you attempted to initiate the
millions of operations that occur every moment, a mistake in the timing of
just one thousandth of a second would derail the operations.

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