Physiology of Electric Shock

Physiology of Electric Shock

Most people have experienced some form of electric shock where electric current causes their bodies feel pain or trauma. If one is working around electric circuits that have high voltage, electric shock becomes more detrimental where pain is the least concern of the shock. Since electric current is conducted through a material, any form of resistance to the flow of electrons leads to energy that is in the form of heat. This is the basic understanding of electricity effect on living tissue where current heats up the tissue. If this heat is plenty, the tissue may be burnt. To put this in a better perspective, the physiological effect of electric shock is similar to the damage that may be caused by an open flame. However, electricity has the ability to cause more harm to the tissues beneath the skin and internal organs.

Another physiological effect of electric current is on the nervous system of the victim. This coordinates the brain, spinal cord, and other sensory organs in the body. Nerve cells communicate to each other and produce neurotransmitters when stimulated by electrical signals (Tasaki, 2012). When electric current of sufficient amount is conducted through a living creature, it supersedes the electrical impulses generated by the neurons. As a result, it overloads the nervous system and prevents the ability of reflex signals to trigger the muscles. Muscles triggered by external current (shock) contract involuntarily, where the victim has no control over it.

The problem of electric current becomes worse when a victim contacts an open circuit with bare hands. Biologically, there is better development of the forearm muscles that are responsible for bending fingers than the muscles responsible for extending the fingers. Therefore, when the two muscles contract due to an electric current that passes through the person’s arm, the bending muscles will dominate (Tasaki, 2012). Eventually, this leads to the clenching of fingers into a fist. If a victim touches a live current conductor through his palm, the clenching action will make the hand grasp the wire more firmly. The victim will be unable to release the wire and this will worsen the electric shock. Medically, the condition of involuntary muscle contraction is referred to as tetanus. To deal with the shock-induced tetanus, the electric current running through the victim should be stopped.

Electric current goes beyond skeletal muscles in a shock victim. Moreover, the diaphragm muscle that controls the heart and the lungs may be “frozen” in a tetanus state by electric current. Even currents that are too low to cause tetanus are able to disorient nerve cell signals, causing the heart not to beat properly.  This condition is called fibrillation and causes the heart to be ineffective in pumping blood to the vital body organs. Eventually, a strong electric current through the body leads to cardiac arrest. However, it is ironical to note that medics make use of a strong jolt of electric current, applied across the chest of the victim, to make a fibrillating heart resume a normal beating pattern. Electric circuits may have Direct Current (DC) or Alternating Current (AC). The effect of AC on the body depends on the frequency where a low-frequency (50-60 Hz) is more harmful that a high-frequency (Kroll & Ho, 2009).  Similarly, a low-frequency AC is five times more dangerous than DC of the same voltage and amperage. This is because it causes a prolonged muscle contraction (tetany) that freezes the hand to the source of current and hence causes an extended exposure. On the contrary, a DC causes a single convulsive contraction that pushes the victim ways from the source of current.  In either way, all electric currents that are high enough to cause a muscle action should be avoided.



Kroll, M. & Ho, J. (2009). TASER® Conducted Electrical Weapons: Physiology, Pathology, and   Law. New York: Springer.

Tasaki, I. (2012). Physiology and Electrochemistry of Nerve Fibers. New York: Elsevier.

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