Human Body Electrical Signals
The nervous system of humans and other animals interprets the world and directs the body to function by sending electrical impulses, or nerve impulses from every part of the body to the brain, and from the brain to the body. For example, when you stub your toe on a rock, this is how it works:
The nerve--composed of cells called neurons, blood vessels, and connective tissue--is stimulated by the blow. There is a sudden loss of potassium from inside the neuron, while sodium ions rush in. This creates a so-called action potential, where the cell contents become positively charged relative to the negatively charged fluid outside--the opposite of a resting neuron.The action potential passes from one neuron to another--an electrical impulse that travels up the nerve toward the central nervous system.The nerve leads to the spinal column and the impulse passes on to the brain, which interprets the signal as pain.If necessary, the brain then sends instructions by a similar but different pathway, leading back to the site of injury.The whole process takes only a fraction of a second.Taser Effects on Body Electrical Signals
Stun guns have exposed electrodes that deliver an electrical charge when the gun is pressed against the victim. Standard Tasers can be used at a distance because they deliver the charge via electrodes attached to long wires actually fired from the gun.
What a Taser basically does is add a lot of electrical confusion to the nervous system: the electricity is delivered at a high voltage but low amperage, and can disable a human in seconds. Initially, the effect is interpreted as pain; however, muscle spasms, confusion, and inability to control movement quickly follow. The brain becomes incapable of interpreting the nerve impulses it's receiving (because they don't, in fact, carry any information it can use) and is unable to send out meaningful instructions to the body.
It's generally believed that Tasers and stun guns are painful but harmless unless they are used inappropriately. They have been credited with saving the lives of many people who law enforcement professionals might otherwise have shot.
When Tasers Kill
From time to time, individuals die after being shot with a Taser, raising important questions about the safety of these devices. They are certainly not non-lethal weapons: although more research is urgently needed, certain groups appear to be at greater risk of suffering serious harm, including death:
people with pacemakerspeople with heart conditionsdrug abusersthose who fall as a result of the loss of muscle controlMost of us would probably prefer a jolt from a Taser to a bullet wound; however, it's clear that, in at least some instances, we still don't really know what that jolt is doing to the body.Read More About Tasers:
Personal Security Products
Other topics in Biology:
How Fluoride Works on Teeth
Theories of How Life Began
Sources:
Basic Human Anatomy and Physiology 2nd ed. Dienhart, Charlotte. W.B. Saunders Company: Philadelphia, 1973.
"How Stun Guns Work." Harris Tom. How Stuff Works
"Taser FAQs." CBC News in Depth. Oct 19, 2007
