Electric current is very similar to the flow of water, only instead of its molecules moving down the river, charged particles move along the conductor.
In order for the electric current to flow through the body, it must become part of the electric circuit.
Direct and alternating current
The degree of the damaging effect of electric current on the human body will depend on its type.
If the current flows in only one direction, it is called constant (DC).
If the current changes direction, it is called a variable (AC). Alternating current is the best way to transmit electricity over long distances.
An AC with the same voltage as DC is more dangerous and has worse consequences. The action of an electric current on the human body in this case can cause the effect of “freezing the muscles of the arm”. That is, there will be such a strong muscle contraction (tetany) that a person will not be able to overcome.
Ways to get hit
Direct contact with electricity will occur when someone touches a conductive part, such as an uninsulated wire. In private homes, this is possible in rare cases. Indirect contact occurs when there is an interaction with any equipment or appliance, and due to a malfunction or violation of the rules of storage and operation, the device body may be shocked.
Interesting fact: why are birds never exposed to electric shock from sitting on cables?
This is because there is no voltage difference between the bird and the power cable. After all, it does not touch the earth, as well as another cable. From here the voltage of the bird and the cable coincide. But if suddenly the wing of a bird touches, say, a metal winding on a pole, the electric shock will not take long.
Impact force and its consequences
Consider the effect of electric current on the human body briefly:
Electricity | the effect |
Below 1 mA | Not perceived |
1 mA | Tingling |
5 mA | A little shock. It doesn’t hurt. A person will easily let go of the current source. Inadvertent reaction can lead to indirect injuries. |
6-25 mA (women) | Painful shocks. Loss of muscle control |
9-30 mA (men) | Non-releasing current. A person may be discarded from a power source. Severe involuntary reactions can lead to involuntary injuries. |
50 to 150 mA | Strong pain. Respiratory arrest. Muscle reactions. Possible death |
1 to 4.3 A | Fibrillation of the heart. Damage to nerve endings. Probable death |
10 A | Cardiac arrest, severe burns. Death is most likely |
When current flows through the body, the nervous system experiences an electric shock. The intensity of the shock depends mainly on the strength of the current, its path passing through the body, and the duration of the contact. In extreme cases, shock causes interruptions in the normal functioning of the heart and lungs, leading to unconsciousness or death. The types of action of electric current on the human body are divided depending on what complications the current caused to the body.
Electrolysis
Everything is simple: an electric shock will contribute to a change in the chemical composition of blood and other fluids in the body. What will further affect the operation of all systems as a whole. If a constant current passes through body tissues for several minutes, ulceration begins. Such ulcers, although usually not fatal, can be painful and take a long time to heal.
Burns
The thermal effect of electric current on the human body manifests itself in the form of burns. When an electric current passes through any substance that has electrical resistance, heat is generated. The amount of heat depends on the power dissipation.
Electric burns are often most noticeable near the area where the current enters the body, although internal burns quite often occur, which, if they are not fatal, can cause long-term and painful injuries.
Muscle cramps
Irritating and exciting living tissue, an electric discharge enters the muscle, the muscle begins to shrink unnaturally and convulsively. Various disorders occur in the body. This is the biological effect of electric current on the human body. A prolonged involuntary muscle contraction caused by an external electrical stimulus carries with it one adverse effect when a person who is holding an electrical object cannot let it go.
Respiratory arrest and heart
The muscles between the ribs (intercostal muscles) must contract and relax many times so that the person breathes. Thus, prolonged contraction of these muscles can interfere with breathing.
The heart is a muscular organ that must constantly contract and relax in order to fulfill its function as a pump for pumping blood. Prolonged contraction of the heart muscles will impede this process and lead to its stop.
Ventricular fibrillation
The ventricles are the chambers responsible for pumping blood from the heart. When an electric shock occurs, the muscles of the ventricles will undergo irregular, inconsistent twitching, as a result the pump function in the heart will cease to work. This factor can be fatal if not corrected in a very short period of time.
Ventricular fibrillation can be caused by very small electrical stimuli. A current of 20 μA passing directly through the heart is enough. It is for this reason that most deaths are due to ventricular fibrillation.
Natural Protection Factors
The body has its own resistance to the actions exerted by electric current on the human body in the form of skin. However, it depends on many factors: on the part of the body (thicker or thinner skin), skin moisture and body area, which is harmful. Dry and wet skin have very different resistance values, but are not the only aspect that should be considered when exposed to electric shock. Cuts and deep abrasions contribute to a significant reduction in resistance. Of course, the resistance of the skin will also depend on the power of the incoming current. But still, there are many cases where, due to the high resistance of the skin, a person, in addition to an unpleasant electric shock, did not receive a single electric injury. The effect of electric current on the human body did not bring any undesirable consequences.
How to prevent electric shock
Prevention of electric shocks, especially in everyday life, is a prerequisite for a safe life. Insulation is used for any live parts. For example, cables are insulated electric wires, which allows their use without the risk of any electric shocks, and light switches enclosed in boxes prevent access to live parts.
There are special low-voltage devices that provide additional protection against electric shock.
RCDs (residual current devices) can provide additional electrical safety. The effect of electric current on the human body in this case will be zero. In the event of an unwanted leak, this device will disconnect a damaged section of the wiring or a faulty appliance in a few seconds, which will not only save people from getting current, but also save them from fire.
Difavtomat, in addition to the features described above, has protection against overload and short circuit.
It is important to make sure that any electrical work carried out in the house is carried out by a qualified electrician who has the technical knowledge and experience to ensure safe work.
The power of electricity in living things
Electrochemical energy is produced in every cell of every living organism. The nervous system of an animal or person sends its signals through electrochemical reactions.
Almost every electrochemical process and its technological application play a role in modern medicine.
The film about Frankenstein uses the specific action of electric current on the human body. The power of electricity turns a dead man into a living monster. Although the use of electricity in this context is still not possible, electrochemical forces are necessary for our bodies to function. Understanding these forces has greatly helped the development of medicine.
The action of electric current: the first experiments
Since 1730, after Stephen Gray’s experiments in transmitting electric current over a distance, over the next fifty years, other researchers have found that touching an electrically charged rod can cause muscle contraction in dead animals. A typical example of the influence of electric current on a biological object is a series of experiments by the Italian doctor, physicist and biologist Luigi Galvani, who is considered one of the founding fathers of electrochemistry. In these experiments, he sent an electric current through the nerves to the frog's paw, and this caused muscle contraction and limb movement.
At the end of the nineteenth century, some doctors began to study the effect of electric current on the human body, but not dead, but alive! This allowed them to make more detailed maps of the muscle system, which were previously inaccessible.
Electrotherapy and tricks
During the eighteenth and early nineteenth centuries, electric current was used everywhere. Doctors, scientists and charlatans, not always different from each other, used electrochemical shocks to treat any disease, especially paralysis and radiculitis.
At that time, specific shows appeared, simultaneously terrifying and wildly delighting. The essence of those was to revive the corpse. Giovanni Aldini succeeded in this matter, who, with the help of electric current, made the dead man “come to life”: he opened his eyes, moved his limbs, and raised himself.
Current in modern medicine
The effect of electric current on the human body, in addition to treatment (as an example, physiotherapy), can also be used for early detection of health problems. Special recorders now turn the body's natural electrical activity into diagrams, which doctors then use to analyze abnormalities. Doctors now diagnose cardiac abnormalities with electrocardiograms (ECGs), brain disorders with electroencephalograms (EEGs) and loss of nervous function with electromyograms (EMGs).
Life thanks to electric current
One of the most dramatic uses of electricity is defibrillation, which in films is sometimes shown as a “trigger” of the heart, which has already stopped working.
Indeed, the triggering of a short-term impulse of a significant magnitude can sometimes (but very rarely) restart the heart. However, more often defibrillators are used to correct arrhythmia and restore its normal state. Modern automated external defibrillators can record the electrical activity of the heart, determine the fibrillation of the ventricles of the heart, and then calculate the current strength needed for the patient based on these factors. Many public places now have defibrillators, so that the electric current and its effect on the human body in this case prevents death caused by heart dysfunction.
Artificial pacemakers that control heart contractions should also be mentioned. These devices are implanted under the skin or under the muscles of the patient’s chest and transmit pulses of electric current of about 3 V through the electrode and heart muscle. It stimulates a normal heart rhythm. Modern pacemakers can work for 14 years before they need to be replaced.
The effect of electric current on the human body has become commonplace, not only in medicine, but also in physiotherapy.