Energy is an important factor in the
function
of our bodies. We often say, "I am lacking
energy"
or "I wish I had more energy." But, what is
energy?
Simply defined, energy is the capacity to do work,
or to place matter into motion. It is the use of
energy by our body that creates the quality we call
"life." There are many forms of energy used by
our bodies: chemical energy, electrical energy,
mechanical energy and electromagnetic energy.
This article will analyze the form of energy called
electrical energy or electricity. It will also describe
how substances obtained in our diets are
responsible in generating this form of energy.
Electricity is a fundamental entity of nature
consisting of negative and positive particles
exhibiting attractions and repulsions. These
attractions and repulsions manifest themselves as
movements of these charged particles, or in other
words--electrical current. This form of energy
plays a critical role in the proper function of our
body.
The key players in creating the electric energy
within our body are structures called ions. An ion
is an atom or group of atoms carrying an electric
charge by virtue of having gained or lost one or
more valence electrons. Valence electrons are those
electrons in the outer ring of electrons orbiting the
nucleus of the atom. Ions may exist in solid, liquid,
or gaseous environments, although those in liquid
are more common and familiar. Most ionic
compounds fall in the category of chemicals called
salts.
Ions existing in a liquid state are electrolytes.
An electrolyte is any compound that, in solution,
conducts electricity and is decomposed or
electrolyzed by the electricity. This form of
compound is ionizable in solution.
Electrolytes, or in other words compounds that
are ionizable in solution, play an essential role in
many body functions. Cells create electrical energy
as ions move from the solutions inside the cells
of our body to the solutions outside the cells. This
form of energy is a staple in the normal function
of many body systems. For example, the nervous
system uses electrical energy, termed nerve
impulses, to transmit messages from one cell in
the body to another cell in the body. This manifests
as muscle movement, glandular secretion, |
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excretion, temperature regulation, and even
mental
thought. Let us analyze, in more detail, the role
of certain ions in some body functions.
In the body, fluids both inside and outside the
cells are electrolyte solutions. This means they are
water suspensions of ions. The electrolyte solutions
both inside and outside the cells contain equal
amounts of positive (cations) and negative (anions)
ions making the body as a whole electrically neutral
(see Table 1). The limiting boundary of the cell,
the cell membrane, separates these ionic solutions.
Generally, a very small excess of anions
accumulates immediately inside the cell membrane
along its inner surface, and an equal number of
cations accumulates immediately outside the cell
membrane. This is the resting state of the cell.
This difference in ion concentration on the adjacent
surfaces of the cell membrane creates an electrical
energy potential or electrochemical gradient. This
is very similar to a battery where one end has a
larger concentration of positively charged particles
and the other end a greater concentration of
negatively charged particles. Completing the circuit
by connecting the ends of the battery allows
charged particles to move between the two ends
creating energy as an electrical current. A similar
energy source arises in the body as charged ions
move across the cell membrane.
In our bodies, the nervous and muscular systems
use the electrolyte properties of ionic sodium and
potassium, assisted by lesser trace elements (e.g.
copper) to generate currents across the membranes
of their cells. This current, or movement of charged
particles, results from the electrochemical gradient
set up across the cell membrane. The
electrochemical gradient sets up the two types of
movement that produce the current. The chemical
gradient results in the passive movement of ions
from a region of higher concentration to a region
of lower concentration. The electrical gradient
creates a movement of ions of one charge to an
area of ions of the opposite charge. The result of
this current is the transmission of nerve impulses
and the contraction of muscle tissue.
The ionic particles of the nervous impulse can
be visualized in the following simplified process.
Neurons, the conducting cells of the nervous
system, communicate by generating and |
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