As of late, popular culture seems very interested in how the human body creates it’s own electricity. The reason appears to be all the amazing things we can do with the harnessed energy produced. The movie ‘The Matrix’ is one example. Technology is allowing the real world to catch up to science fiction. Using the human body like a battery, as portrayed in the movie, is more reality than you might think. Just this year, 15 year old Ann Makosinski from Canada created a flashlight powered by body heat. The flashlight lights up by simply holding it.
How do our bodies create this power? The short answer is chemical energy. If that seems too short for you, keep reading. The long, and more specific, answer is much more interesting.
What most people think of as electricity, is simply the movement of an electrical charge, or potential. To move, and as a result use, this potential, we need an energy source. When it comes to electricity, there are countless numbers of sources that can create electrical power. The most common energy sources powering the United States power grid are hydro-electric, nuclear, fossil fuels, solar and wind. Technological advances have allowed us to harness these energies, giving us wonders like computers and smart-phone flashlights. Yes, there is an app for that!
Because electricity needs an energy source to create it, it’s sometimes known as a secondary energy source or an energy carrier.
What exactly are we harnessing from these energy sources? The power to move electrons. Thinking back to junior-high school science class, you might remember different atoms have different numbers of protons, electrons and neutrons. Protons being positive, electrons being negative and neutrons being neutral.
Basic elements in our universe, like the oxygen you breathe, and the calcium and potassium you eat, have a certain number of protons and electrons, distinguishing it from other elements. Most elements have the same number of electrons as they do protons. This gives the atom a balance between negative and positive charges. For ease of explanation, protons reside in the nucleus (center) of the atom while electrons rotate around the nucleus. More specifically, quantum mechanical principles dictate electron movement and spin, but I’ll save that for a publication more dedicated to physics and not medicine.
An interesting fact about electrons is, the energy holding them to the atom is restricted to specific levels. These levels are known as shells. Shells allow for specific spaces between the rotating electron and the center protons. For ease of picturing this in your head, its similar to how different satellites orbit the earth at different distances. Since negatively charged electrons are attracted to positively charged protons, the further away from the center of the atom an electron is, the more loosely the electron is held to the nucleus and the easier it is to knock that electron free of it.
Electrons residing in the outermost shell of an atom, known as the valence shell, are so loosely connected to the nucleus, its rather easy to cause them to break away. If you get enough energy to break an electron free, causing it to move in a certain direction, electrons in the valence shell of an adjacent atom will move to that atom, because as we know, in most cases you need an equal electron to proton ratio in any given element. This flow of electrons is what we’re harnessing from outside power sources, and its what we’re referring to as electricity.
Back to the question at hand. How does the body create this flow of electrons? As stated before, the energy source is chemical.
The energy created by chemicals is due to the reactions of the atoms and molecules present. As mentioned before, all the elements we take in our bodies, like oxygen, sodium, potassium, calcium, and magnesium, have a specific electrical charge. Meaning they have a specific number of electrons, protons and neutrons. Those specific charges, weather positive or negative, react to the charges of adjacent molecules. This reaction is what creates the energy needed to move electrons. Specifically, the force is known as electromagnetic. Electromagnetism being one of the 4 known fundamental forces in our universe. The other three are gravity, nuclear weak, and nuclear strong.
When we eat or drink, the large molecules within our food get broken down by digestion, creating smaller molecules. Those smaller molecules can be used by our cells to do work. This process is called cellular respiration. All of those molecules and elements in our bodies have the potential to create electrical impulses. Those impulses are dependent on the situations within the specific body systems, like the brain or heart, at the time.
Arguably, the most famous electrical current within our bodies, is our heart rhythm. Hearts contain within them, a grouping of cells known as your Sinoatrial node (SA node). The cells within the SA node, sometimes called the pacemaker of the heart, contain electrolytes both inside and outside of the cells. The most common electrolytes within the body are sodium, potassium, calcium, magnesium, phosphorus, and chloride. Sodium and calcium generally reside outside the SA nodes cells. Potassium generally lies within them. The cell membrane acts as a barrier between these electrolytes.
Pressure within the bloodstream allows sodium to enter the cell causing potassium to leave it. Less potassium leaves the cell than sodium entering it. The result is a continually growing positive charge. When that charge reaches a certain point, calcium channels in the cell membrane open up and allow for calcium to enter. This makes the interior of the cell extremely positive compared to outside the cell, known as an action potential. Once that potential reaches a certain point, it has enough “power” to discharge down the nerves of the heart. This electricity causes the muscles to contract and your heart to beat. Ah, the wonders of chemistry in action!
Electrolytes crossing cell membranes, creating electrical discharges, is only one of countless ways the body uses the food we eat to create energy and power to do work. This is why the food content we eat is classified in calories. A calorie being a unit of energy. Medical science is continuing to unravel all of the mysteries surrounding how those chemical reactions maintain our daily lives. You can be sure though, as technology advances, more enterprising individuals like Ann Makosinski will find new and exciting ways to harness the power created by our bodies.