Effects of electric current on human body

Pataasin ang iyong marka sa homework at exams ngayon gamit ang Quizwiz!

Burns may be sharply demarcated on the skin and extend well into deeper tissues

...

High voltage may cause coagulation necrosis of muscle or other internal tissues between source and ground points of the current

...

What is the resistance of moist thin skin?

0,5 kOhms/cm2

What is the threshold of perception for current entering the hand for AC?

1-5 mA (at 60 Hz)

What is the resistance of dry well-keratinized intact skin?

20-30 kOhms/cm2

How many times more dangerous are AC than DC of the same voltage and amperage?

3-5 times

What is the threshold of perception for current entering the hand for DC?

5-10 mA

What is the household current?

50-60 Hz AC

How much is high-voltage?

>500 to 1000 V

What do DC tends to cause?

A convulsive contraction, often forcing the victim away from the current´s source

What is electric voltage?

A difference of electrical potentials

What is electric current?

A flow of particles having an electric charge (electrons, positive and negative ions)

What is an electrolyte?

A good conductor

What can induce ventricular fibrillation?

A low-voltage AC current (110-220 V, 50-60 Hz) traveling through the chest, at amperage as low as 60-100 mA, for DC 300-500 mA is required

What is the "let-go current" for AC?

About 15 mA, varying with muscle mass

What is the "let-go current" for DC?

About 75 mA for a 70 kg man

What is AC?

Alternating current The voltage is changing (electrical outlet)

What is electric current measured in?

Ampere

What is an electrical potential?

An electrical characteristic of certain place

Why s the duration of current flow through the body directly proportional to the extent of injury

Because longer exposure breaks down tissues and allowing internal current flow

How is electrical voltage measured?

Between two electrical potentials (places)

How to treat people with electrical damage?

Break contact of victim and current source by shutting off the current or move the victim

What does any deterioration in the level of consciousness mandates?

CT or MRI scan to rule out intracranial hemorrhage

What can occur during "bathtub accidents"?

Cardiac arrest without burns

What is the most common cause of death of lightening?

Cardiopulmoary arrest

What does electric current flowing through muscles cause?

Contractions

What do high-voltage currents tend to cause?

Deep burns

What is DC?

Direct current The voltage does not change (battery)

What can powerful muscle contractions, or falls secondary to the electric shock, result in?

Dislocations, vertebral or other fractures, blunt injuries, and loss of consciousness

What is the resistance of punctured skin or skin with moist mucous membranes?

Down to 0,2-0,3 kOhms/cm2

What is the baseline assessment for all electric injuries?

ECG, cardiac enzymes and urinalysis, especially for myoglobin

What does lightening cause?

Entry and exit wounds, and seldom muscle damage or myoglobulinuria because the duration of current is too short to break down the skin and tissues

What should you do if the victim can be safely touched?

Examinate for vital functions (pulse, respiratory function, consciousness) Airway stabilization

What can happen if the skin resistance is low?

Extensive burns, cardiac arrest may occur

70 mA can be ..

Fatal

1 mA can be ..

Felt

What does electric current flowing through the heart cause?

Fibrillation of the heart

How to rescue people with electrical damage from low voltage (110-220 V) currents?

First well insulate yourself from ground and then use an insulating material to pull the victim free

How do you treat myoglobinuria?

Fluid replacement and alkalinization therapy is essential to reduce the risk of renal tubular mypglobin precipitation

What are the reason of charged particles movement?

Free charged particles move from places with high concentration to places with low concentration

What do low-voltage currents tend to cause?

Freezing to the circuit

What are the number of cycles in 1 second in AC called?

Frequency, measured in Hertz

Higher voltage and amperage leads to ...

Greater damage

What other damages can occur of lightening ?

Heart asystole, brain confusion, loss of consciousness, neuropsychologic sequelae

What do current flow produce?

Heat, damaging internal tissue

High resistance equals to ..

High production of heat

What can result in acute renal failure?

Hypotension, fluid and electrolye disturbances and severe myoglobinuria

Explain the equation I = U/R

I - electric current U - voltage R - resistace The higher the voltage (U), the higher is the value of I (amperage) On the other hand, the higher the resistance (R) is, the lower is the value of electric current

Equation of electric current

I = Q/t (A)

Which equation express the current flowing through any circuit?

I = U/R

When is a substance able to conduct the electrical current?

If it contains free charged particles

When is cardiac monitoring used?

If there is any suspicion of cardiac damage, arrhythmias or chest pain

Where can electric current be present?

In solid substances (metals), liquids (electrolytes) and gases (ionized gases)

What are the cell membranes?

Isolants

What does the effects of AC on the body depend on?

Largely on the frequency

>15 mA causes ..

Loss of muscle control

Which internal tissues are preferentially damaged by electric current?

Low density tissues that conduct electricity easy, like nerves, blood vessels and muscles

What can occur when the veins coagulate and muscles swell?

Massive edema

What happens if the skin resistance is high?

Much energy may be dissipated at the surface as current passes through the skin, and large surface burns can result at the entry and exit points

What do household current (50-60 Hz) cause?

Muscle tetany, often freezing the hand to the current´s source; prolonged exposure may result, with severe burns if the voltage is high

What are the most common long-term consequences of lightening?

Neuropsychologic damage, pain syndromes, and sympathetic nervous system damage

Can DC pass through the cell membranes and flow intracellular?

No

How to rescue people with electrical damage from high voltage currents?

No attempt to disengage the victim before the power is shut off

What is electric current?

Number of charged particles, which flow through a cross-section conductor in the defined time

What is body resistance measured in?

Ohms/cm2

5 mA is ...

Painful

Where is the body resistance concentrated?

Primarly in the skin and varies directly with the skin´s condition

What injuries can current to the head cause?

Seizures, intraventricular hemorrhage, respiratory arrest, ventricular fibrillation or asystole, and as a late effect cataracts

What can altered physiologic functions after electrical current result in?

Severe involuntary muscular contractions, seizures, ventricular fibrillation or resperatory arrest (apnea) due to CNS injury or muscle paralysis

What happens when a electrical potential is present?

The charged particles start to move in the direction from the place of the highest potential to the place of the lowest potential

Wat does the clinical manifestations of electrical injuries depend on?

The complex interaction of the factors

What does the damage caused by electric shock depend on?

The current flowing through the body

What is the most common exit point for electricity?

The foot

What is the most common entry point for electricity?

The hand, followed by the head

What does electric current flowing through the brain cause?

The loss of conciseness and seizures

What is "let-go current"?

The maximum amperage that can cause the flexors of the arm to contract, but that allows a person to release his hand from the current´s source

Which type of current traveling through the body is most dangerous?

The ones that is likely to transverse the heart, like from arm to arm, arm to foot

What happens with the free charged particles when the electric voltage is present?

The particles start to move in the direction from the place of the highest electric potential to the place of the lowest electric potential

What does free charged particles perform until the electric voltage is present?

The thermal motion

What other damage can occur after electrical current?

Thermal, electrchemical, hemolysis, protein coagulation, vascular thrombosis, dehydration, muscle and tendin avulsion

What are "bathtub accidents"?

Typically, when a wet (grounded) person contacts a 110-220 V circuit (from a hairdryer or radio)

When can a current lower than mA (AC or DC) cause fibrillation of the heart?

When the current has a direct pathway to the heart (e.g. via a cardiac catheter or pacemaker electrodes)

Are human tissues sensitive to the flow of electric current?

Yes

Can AC pass through the cell membranes and flow intracellular?

Yes

Is DC (zero frequency) less dangerous than AC?

Yes

Is low-frequency currents of 50-60 Hz (cycles/s) more dangerous than high-frequency currents ?

Yes

Is the duration of current flow through the body directly proportional to the extent of injury?

Yes

Is the extracellular fluid an electrolyte?

Yes

Is the intracellular fluid an electrolyte?

Yes


Kaugnay na mga set ng pag-aaral

Regulations of the Insurance Industry and State Law

View Set

Module One: Impact of Digital Technology Quiz

View Set

react interview questions part 3

View Set

PN Human Growth and Development: Developmental Assessment 3.0 Case Study Test

View Set

Prep u health assessment chapter 14

View Set

3 mechanisms that contribute to hemostasis and blood clotting

View Set