Anatomy And Physiology

How does Energy Flow in the Body



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There are very many branches of alternative therapy that talk in terms of improving or enhancing energy flow but how does energy flow around the body?

When we talk about having energy, we generally mean that we feel fit and healthy, able to stay active and get things done.  When we feel out of energy, we say we are tired.  We think of getting more energy as making us feel better and healthier.  This popular use of the word energy is fine for describing how we feel but is not precise enough to describe what actually happens in our bodies.

Energy is the word we use to describe the ability to do work, and in nature it comes in only seven known forms: mechanical, gravitational, thermal, electrical, chemical, nuclear, and mass.  We can demonstrate that the amount of energy in the universe remains constant although it can be converted from one form to another.  

We know for certain that there are no other hidden forms of energy - if there were, all of our successful predictions based on science would turn out to be incorrect, and they don't. So when we talk about energy in the body, we must be talking about one of those known forms of energy.

Where does the body get its energy from?
Although we feel warm when we go out in the sun, we cannot directly use that heat for our metabolism.  Instead we have to get our energy from out food, and that energy is stored in the chemical bonds of the molecules that we eat.

Somehow or other we have to liberate that energy and get it to where we need to use it in the chemical reactions going on throughout our bodies.  We can't get our energy in any other way but through our food.  So the process of digestion is geared towards breaking down our foods to get the materials we need as building blocks for our tissues, and also liberating that energy that is stored in our diet.

Unfortunately, we are biologically restricted to this form of getting our energy and nothing we say or do can change that.  Exposing ourselves to other forms of energy will either do nothing or, in excessive quantities, will do us harm.  High doses of radiation are fatal.  High electromagnetic forces are too.

How does the body liberate the energy?
The energy stored in our food is present in the chemical bonds holding the molecules together.  By breaking down those molecules to smaller molecules using enzymes, the energy from the bonds is freed up.  But left to their own devices, these reactions will simply dissipate the energy as heat: we would warm up a little as the reactions took place and then the heat would leave our bodies.

Instead of losing the energy as heat, our metabolism captures that energy into other chemical bonds which are much easier to control.  Two chemicals are particularly important, adenosine diphosphate and adenosine triphosphate, ADP and ATP.  

These are remarkable chemicals because adding some energy and a phosphate ion allows ADP to turn into ATP.  Similarly, ATP can break down into ADP and some liberated energy.  So by moving ADP and ATP around the body, we have a wonderful system for moving chemical energy, the only kind our bodies can use.

How is energy stored in the body?
Clearly, if all the energy is used as soon as it is liberated from our food, we would be condemned to a life of perpetual eating.  But humans also have a mechanism for storing energy.  We are able to create molecules in the body that have chemical bonds which store that energy until we need it.

The body can convert glucose into a form which contains a phosphate ion, Glucose-6-P which stores more energy than the glucose molecule itself.  It can also join these new molecules into a chain providing an excellent mechanism for storing chemical energy, and the chain is called glycogen.  Glycogen is stored in the liver and muscles.

When the body needs more energy, it breaks down the glycogen freeing the energy stored in those phosphate bonds.  Insulin is one of the hormones involved in this process.

How does energy flow around the body?
Energy is moved around the body in the blood stream in the form of chemical energy in molecules such as ATP.  The tissues themselves free up the required energy by using ADP and ATP.

So the picture of energy itself flowing along channels or pathways in the body is quite incorrect.  The energy is already available in the tissues in the form of ATP and can be liberated and used by converting it to ADP when it is needed. Human tissues possess an enzyme called ATPase which can split the bond to free up the energy.  We liberate the energy in situ, as and when it is needed.

Can we add extra energy-rich substances?
Unfortunately this too is impossible.  Our biochemistry is the result of evolution and we cannot simply change it by choice.  For example, although cellulose is found in all plants and contains huge amounts of energy in its chemical bonds, humans can't digest it.  We simply can't use the energy stored in cellulose.

So why not simply eat more ATP?  ATP is a fairly large molecule and it will be chopped up by the enzymes of the gut, denaturing it without providing the energy.  ATP supplements just don't work.

In any case, trying to modify our biochemistry is not advisable because changing the balance of very finely tuned biochemical processes can have unpredictable results.  It is far better to rely on a balanced diet for all the energy required.

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