An electric shock occurs when the body becomes part of an electrical circuit, allowing current to flow through tissues and disrupt normal biological function. The severity of the resulting injury varies widely, ranging from a slight tingling sensation to immediate death. Damage occurs through two primary mechanisms: interference with the body’s electrical signaling systems and the conversion of electrical energy into heat. Understanding which organs are most susceptible to these effects is crucial for assessing the danger of an electrical exposure. The most likely organ to be fatally affected by the passage of electrical current is the heart.
The Primary Target: Cardiac Disruption
The heart is uniquely vulnerable to electrical current because its function is regulated by its own intrinsic electrical system. Fatal electrocution most often results from current passing through the chest, which directly interferes with the heart’s natural rhythm. Even a small current, sometimes as low as 50 to 100 milliamperes, can be lethal if it crosses the heart. This small amount of current is enough to trigger a chaotic, uncoordinated quivering of the ventricles known as ventricular fibrillation (V-fib).
Ventricular fibrillation prevents the heart from effectively pumping blood, leading to a sudden loss of circulation. The heart’s electrical system is particularly sensitive to alternating current (AC) at the 60-Hertz frequency common in household wiring, which is highly efficient at inducing V-fib. Currents below the “let-go current” threshold—the level at which a person can no longer voluntarily release the electrified object—can still be deadly if they pass through the cardiac tissue.
Secondary System Damage: Neurological and Respiratory Effects
Beyond the heart, the nervous system and respiratory muscles are also highly susceptible to the disruptive effects of electrical current. The immediate passage of electricity can cause a massive, involuntary contraction of muscles called tetany. If this current pathway involves the muscles of the chest, such as the diaphragm and intercostal muscles, it can result in respiratory paralysis. This muscle spasm essentially freezes the breathing process, causing suffocation even if the heart is not immediately thrown into V-fib.
Direct injury to nerve tissue, both in the brain and the peripheral nerves, can also occur along the current’s path. High-voltage exposure can immediately damage the central nervous system, leading to symptoms like loss of consciousness, confusion, or seizures. Delayed neurological damage is also a recognized complication, sometimes manifesting weeks or months later as memory loss, movement disorders, or chronic pain due to peripheral nerve damage.
Physical Manifestations: Electrical Burns
Another major component of electrical injury is the physical, thermal destruction of tissue caused by the conversion of electrical energy into heat. This process is known as Joule heating, where the body’s resistance to current flow generates intense heat along the current’s pathway. The skin, with its high resistance when dry, is often the site of the most visible external damage, typically showing distinct entrance and exit wounds. These wounds may appear deceptively small but can indicate a much larger internal injury.
The body’s internal tissues, including muscle, bone, and organs, can suffer devastating deep-tissue burns that are not apparent from the outside. Bone is particularly resistant, causing heat to build up around it, which can lead to widespread necrosis (tissue death) of surrounding muscle. This internal burning can lead to severe complications, such as compartment syndrome, where swelling causes dangerous pressure buildup within muscle groups. These thermal injuries are a mechanical consequence, distinct from the systemic electrical failures affecting the heart and nervous system.
Factors Determining Injury Severity
The ultimate severity of an electric shock injury is determined by several external factors related to the exposure event. The path the electrical current takes through the body is highly significant; a current traveling from one hand to the other, or from a hand to a foot, is more likely to cross the heart and cause cardiac arrest. The duration of contact is also a major determinant, as a longer exposure time increases the total energy delivered to the tissues, amplifying both the electrical and thermal damage.
The type of current makes a difference, with alternating current (AC) generally considered more dangerous than direct current (DC) at the same voltage. AC tends to cause sustained muscle contraction, which can lock the victim onto the source and prolong the exposure time. Furthermore, the magnitude of the current, which is influenced by the voltage and the body’s resistance, dictates the extent of injury. Wet skin or a wet environment dramatically lowers resistance, allowing a much higher current to flow through the body, which can make even a low-voltage shock fatal.