An electric shock occurs when an electric current passes through the human body. While minor static discharges are generally harmless, contact with household or industrial power sources poses significant danger. Understanding how electric shocks affect the body is important for recognizing potential harm and preventing incidents.
Electricity’s Path Through the Body
The human body, composed largely of water and electrolytes, functions as a conductor of electricity. When a person comes into contact with an electrical source and a ground, their body completes an electrical circuit, allowing current to flow.
The fundamental concepts of electricity involve current, voltage, and resistance. Current refers to the flow of electrical charge, measured in amperes (A) or milliamperes (mA). Voltage represents the electrical pressure or force that drives the current, measured in volts (V). Resistance is the opposition to current flow, measured in ohms (Ω).
The skin provides the primary resistance to electrical current, with dry skin offering significantly more resistance than wet or broken skin. Once the current breaches the skin, it travels through internal tissues, which have much lower resistance, allowing for greater current flow.
The path the electrical current takes through the body is a major determinant of injury severity. Current passing from one hand to the other, or from a hand to a foot, is particularly hazardous because it is likely to traverse the chest, including the heart and lungs.
How Electrical Current Affects the Body
When electricity passes through the body, it interferes with natural electrical signals like nerve impulses and muscle contractions. The body uses these impulses to control muscle movement and transmit sensory information. An external current can override these signals, causing involuntary muscle spasms that prevent a person from letting go of the electrical source.
The heart, controlled by its own electrical system, is particularly vulnerable to electrical current. Disruption of its rhythm can lead to ventricular fibrillation, a chaotic beating pattern that prevents effective blood pumping. This can rapidly result in cardiac arrest and loss of consciousness. Electrical current can also affect the nervous system, potentially causing pain, tingling, numbness, and weakness.
Factors Influencing Shock Severity
The amount of current (amperage) flowing through the body is a critical determinant. Even small currents, like 10 milliamperes (mA), can cause muscle contractions severe enough to prevent release from the source. Voltage, the electrical pressure, influences how much current is driven through the body’s resistance.
Body resistance, primarily from the skin, varies based on moisture, calluses, and contact area. Wet skin significantly lowers resistance, increasing the potential for a more severe shock.
The current’s path through vital organs like the heart or brain is considerably more hazardous. The duration of contact directly correlates with the amount of energy dissipated, leading to more extensive damage over longer periods. Alternating current (AC), common in households, is often considered more dangerous than direct current (DC) at similar voltages because it can cause continuous muscle contractions and is more likely to induce ventricular fibrillation.
Potential Injuries and Consequences
Electric shocks can result in a wide range of injuries, from superficial to life-threatening. Electrical burns are common and can be extensive, often appearing at entry and exit points. These burns are dangerous because external appearance may not reflect the severity of internal tissue damage, which can affect muscles, nerves, blood vessels, and organs.
The heart’s electrical system can be severely disrupted, leading to cardiac arrest or various arrhythmias, including ventricular fibrillation. The nervous system can suffer damage, resulting in immediate symptoms like seizures, loss of consciousness, or amnesia. Long-term neurological consequences may include memory loss, chronic pain, and cognitive difficulties.
Muscle and tissue damage can be profound, sometimes causing rhabdomyolysis, where damaged muscle fibers release contents into the bloodstream, potentially leading to kidney failure. Severe muscle contractions can also cause bone fractures or joint dislocations.
Safety and Prevention
Preventing electric shocks involves mitigating common electrical hazards. Regularly inspect electrical cords and plugs for fraying, cracks, or exposed wires, as damaged cords pose immediate risks. Promptly repair or replace damaged electrical equipment.
Avoid using electrical appliances near water sources, such as sinks, bathtubs, or swimming pools, as water significantly increases conductivity and shock risk. Install ground fault circuit interrupters (GFCIs) in moist areas like bathrooms and kitchens. GFCIs provide protection by quickly cutting off power if a fault is detected. Avoid overloading electrical outlets and be cautious around outdoor power lines, treating all downed lines as potentially live.