Electric shock occurs in contact with an electrical circuit in which there are voltage sources and / or current sources capable of causing current to flow through a part of the body that has come under voltage. Usually sensitive to humans is the passage of a current of more than 1 mA . In addition, in high voltage installations, electric shock is possible without touching live parts as a result of current leakage or breakdown of the air gap with the formation of an electric arc .
The strength of the lesion and severity depends on many factors: the discharge power , the exposure time , the nature of the current ( constant or variable ), the state of a person - the state of health, age, body moisture, as well as the place of contact and the passage of current through the body.
In case of electric shock, disturbances in the activity of the cardiovascular system, respiration, nervous system, and electric burns can be observed. The time of onset and the severity of these disorders vary widely.
According to severity, electric shock is divided into four degrees:
- First degree . Convulsive muscle contractions are observed without loss of consciousness.
- Second degree . Convulsive muscle contraction and loss of consciousness are characteristic.
- Third degree . Against the background of a convulsive muscle contraction with loss of consciousness, there are disturbances in cardiac activity or breathing.
- Fourth degree . Clinical death . The cause of death may be: primary paralysis of the heart; primary respiratory paralysis; simultaneous paralysis of the heart and breathing; electric shock (brain paralysis); heavy electric burns.
Under the influence of a low voltage current, spinal atrophic paralysis may occur due to damage to the gray matter. Its development is also delayed - after weeks or months, weight loss occurs in the muscles innervated from the segments through which the current passed. After a few months, the process stabilizes, sometimes improvement is possible.
Damage to the brain. The skull has high resistance, protecting the brain from exposure to electricity. Only high voltage current passes through it. The heat generated during this passage causes blood coagulation in the underlying dural sinuses and brain coagulation necrosis. The effect of electric current causes cerebrovascular complications, such as cerebral infarction, subarachnoid and intracerebral hemorrhages. The exact reason for their development is unknown. Probably a high temperature causes coagulation necrosis of the endothelium and the muscle membrane of the vessels of the brain, the arteries become dilated, and fusiform aneurysms form. In addition, thrombosis, cardioembolism from a parietal thrombus, and rupture of a vessel may develop. Thrombosis of venous sinuses can also be the cause of cerebral infarction. Other causes of cerebrovascular complications may be acute intracranial hypertension (up to 400 mm. Water column) and cardiac arrest.
Electric current contributes to an exacerbation of a chronic pathological process or the development of a new disease. Electric current more than other traumatic factors, has the ability to cause disturbances in all body systems at the time of its exposure. Therefore, it is difficult to determine the further course and outcome of the disease in the first hours and even the next days after an electric injury.
Often severe electrical trauma ends in death, the mechanism of which boils down to three points: • inhibition of the functions of the medulla oblongata • ventricular fibrillation caused by the direct passage of electric current through the heart • tetanic spasm of the respiratory muscles
In the distant period after an electric trauma, a psycho-organic syndrome sometimes develops due to progressive atrophy of the brain substance and hydrocephalus. Persistent headaches, asthenization, memory impairment, emotional and autonomic lability are characteristic. Peripheral autonomic syndromes are also frequent (local cyanosis, hyperhidrosis or anhidrosis, local graying or hair loss, etc.). After electrical trauma, prolonged asthenic conditions are possible, in which psychopathies are often noted. Differentiation of these syndromes, sometimes outwardly similar, requires a detailed clinical examination.  Even after several years, persistent disorders of the nervous system remain. But the current not only enhances the diseases that were previously, it is able to become the trigger for epilepsy and schizophrenia. And besides, after an electric shock, pain with a stomach ulcer intensifies, sciatica worsens, long-overgrown fractures begin to hurt. 
An electric burn is damage to tissues in places of entry, exit, and in the path of current flow.
Electric burns are a common component of electrical injury. It is customary to distinguish the following types of burns with electrical injury:
- electric burns (burn from electric shock);
- mixed burns (in case of mixed lesions there is an electric burn and a thermal burn from a flame of an electric arc or burning clothing);
- combined lesions (this is a combination of electric burns with mechanical injuries, often the victims recline away from current-carrying objects. As a result, they may receive damage to soft tissues, bones, closed craniocerebral injuries)
Electric burns occur when an electric current of considerable strength and voltage passes through the tissue. Since human skin has a strong resistance to electric current, the greatest damage is observed at the points of entry and exit of current.
Electric burns are divided by the depth of the lesion in accordance with a classification similar to thermal burns . However, electric burns almost always cause deep damage, so lesions I and II are rare. In this regard, it is justified to distinguish only two degrees of electric burns:
- The third B degree is necrosis of the skin and subcutaneous tissue.
- The fourth degree is necrosis of muscles and bones.
Most often one encounters contact electric burns, the so-called current marks, which are formed at the points of current input and output and are caused by thermal action and metallization due to electrochemical action. They can look from a point hemorrhage, a cut or stab wound, to charring a part of the body. Most often, “current marks” represent a round defect of a different color (from whitish to dirty brown). Their diameter ranges from a few millimeters to 3 cm. In the center there is a recess with a burn of tissue of the IIIb degree or even carbonization, along the edges there is a roll-like thickening. The surrounding skin has the appearance of a honeycomb, the formation of which is due to the "explosion" of tissue fluid (turns into steam) at the time of passage of current. They are not painful and are not accompanied by reactive vascular reactions. A feature of electric burns is the loss of sensitivity of intact skin near the damage zone, this is due to damage to nerve fibers and skin receptors.
The depth of the lesion with electric burns is difficult to determine. The mismatch between the visible surface of the burn and the true lesion volume is characteristic, since tissues located under the skin often die at a much greater distance. Sometimes there are lesions of muscles, nerves, blood vessels and bones. Vascular disorders often occur, their causes are varied. Large vessels can be coagulated with surrounding tissues, as thrombosis develops due to current damage to their intima.
- Due to the high electrical resistance of human tissues, their heating occurs rather quickly, which causes burns .
- Even relatively small voltages, on the order of 110–230 V , with short-term contact with the chest can cause a malfunction of the heart muscle (60 mA for alternating current, 300–500 mA for constant). An electric shock is also used to restore the heart , thereby eliminating the effect of fibrillation . Such a device is called a defibrillator .
- An electric shock can cause a malfunction in the nervous system , for example, erratic muscle contractions . Repeated strokes can cause neuropathy . Acute electrical injury can cause asystole .
- If the head is damaged by electric shock, loss of consciousness is possible. When executing criminals in an electric chair, the positive conclusion is connected to the head of the suicide bomber, while the rest of the chair is the negative conclusion.
- With sufficiently high voltage and current strength, so-called electric arcs can occur, causing severe thermal burns.
Veterinary Electric Shock
Electrical injuries occur due to improper installation of electrical installations used in animal husbandry, lack of grounding, contact of animals with poorly insulated or dangling wires or objects resulting in breakdowns that turn out to be current-carrying. It is easy to diagnose electrical trauma by characteristic nerve phenomena and history. 
- Lightning strike
- Electrical Installation Rules
- electrical safety
- [http: www.forens-med.ru/book.php? Id = 2068 Rybalkin R.V. Kudyanov E.G. Damage to the nervous system by electric shock. // Selected issues of forensic medical examination. - Khabarovsk, 2007 - No. 81. - S. 106-109.]
- Electric shock // AiF. Health »No. 32 09/08/2000
- B.V. Usha et al. Internal diseases of animals. - M .: KolosS, 2010 .-- 311 p.