Physiology of Electric Shock

Physiology of Electric Shock

Most people have experienced some form of electric shock, where electric current causes their bodies to experience trauma or pain. If such persons are fortunate enough, the extent of their experience is limited to tingles from static electricity building up and discharging through their bodies. When people are working around electric appliance capable of delivering high power, electric shock becomes an issue where pain is the least significant result as it can lead to death. This paper seeks to give a brief discussion of the physiology of electric shock.

When electric current is conducted through a material, any resistance to the flow of electric current results in dissipation of energy, and this energy is usually in the form of heat (Myers, 2006). This is the most easy to understand effect of electric current on living tissue. Whenever the amount of heat is high enough, the tissue may burn. This effect can physiologically be equated to any damage caused by high temperature source of heat or flames; however, electric current can burn tissues beneath the skin, and this effect can be fatal to the major internal organs like the heart.

            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 significant magnitude pass 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.

            When an electric shock affects an individual, the electric current penetrates beyond the superficial layer of the skin. Moreover, the diaphragm muscle that controls the heart and the lungs may be “frozen” in a tetanus state by electric current. Equally important to note is that even low currents affect nerve cell signals and hence causing irregular heart beat.  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 than 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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