Physiology of Electric Shock

Most people have experienced some form of electric shock where electric current causes their bodies to 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. When electric current is being conducted, heat energy is produced if the resistance to the electrons flow is detected. This explains the effect of electricity current to a living tissue. In some cases, excessive heat may burn the tissues. 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.

When an individual is affected by an electric shock, 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.

References

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.