which path does electricity take when conducted thru bodily tissues

Discussion in 'General Electronics Chat' started by pager48, Mar 22, 2019.

  1. pager48

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    Nov 25, 2018
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    wouldn't it always be the veins and arteries since they are uniformly conductive structures?
     
  2. OBW0549

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    Mar 2, 2015
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    NO.

    ALL tissues in the body conduct to some degree or other. Don't even try to guess which conduct most or least.
     
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  3. BR-549

    AAC Fanatic!

    Sep 22, 2013
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    There are ion conductive channels galore, and various, changing, charge densities all over the body.

    Even an external field can re-configure your electrical composition.

    Your body is an immense electrical and chemical network.

    And don't forget, chemistry is charge transfer, electricity is charge rotation.

    Chemistry and electronics are brother and sister.
     
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  4. nsaspook

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    Aug 27, 2009
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    I would guess it depends on the type and power of the voltage source and how the all tissue in the current path handle the thermal energy generated.

    I've seen the effects of a high voltage/hgh power DC and RF burn from the finger tips to the forearm on a person repairing a 2-30MHz tube amplifier at full power. There was a cauterized to carbon interior channel following the veins and arteries (I don't remember seeing any blood flowing from the burns, only rancid smelling smoke) to the exit point of the forearm and very extensive arc damage to the tissue from the thumb, palm entry point and forearm exit point. It was his good luck we had a surgical team on-board for the Marines as they saved arm with most of the hand function after we made sure he was alive and stable after the shock.
     
    Last edited: Mar 22, 2019
  5. nsaspook

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    This is the person later after surgery with the bandage on the right hand looking at the same type of amplifier that almost killed him.
    [​IMG]
     
  6. jpanhalt

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    Last edited: Mar 23, 2019
  7. spinnaker

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    Are you looking for the best way to electrocute someone? ;)
     
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  8. SLK001

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    It's always the path of least resistance.
     
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  9. nsaspook

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    The veins and arteries don't have zero impedance so some of the current flow is also in connecting tissue because there is an electric potential across all the body mass just like a parallel resistor circuit.
    res50.gif
     
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  10. SamR

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    Mar 19, 2019
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    And then there are the flash burns from plasma arcs without even coming into contact with a conductor. It was standard practice in substations and motor control rooms to ALWAYS shut the compartment door of the breaker/starter before energizing the circuit just in case. And NEVER stand in front of the compartment when doing so.
     
    Last edited: Mar 22, 2019
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  11. WBahn

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    Mar 31, 2012
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    This tends to be very misleading for many of the people that ask the kind of question for which this answer is offered.

    They frequently walk away "knowing" that if the current has a choice of a 100 Ω path or a 101 Ω path that it will ALL take the 100 Ω path since that's the path of least resistance.
     
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  12. WBahn

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    Even if that's true, you are making the very mistake I cautioned about in my prior post.

    The muscles and fat tissues are hardly non-conductive.

    But let's, purely for the sake of discussion, say that a person's blood has only one-tenth the resistivity of their muscle and fat tissues. Let's further stipulate that the resistance encountered in getting the current through the blood vessel walls is negligible. What fraction of the cross section of their arm, for instance, is blood vessels? Let's say it's 5%. That means that the overall resistance of their muscle/fat tissues is about half that of their blood vessels and so about 2/3 of the current will go through the tissue and about 1/3 through the vessels.
     
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  13. WBahn

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    Why? Based on what?

    The current density may well be higher in the blood vessels than the other tissues. That does NOT translate to a higher fraction of the total current doing so. Additional information is needed to explore whether or not that's the case.
     
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  14. SamR

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    Mar 19, 2019
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    Let's take a plate of nonconductive material. On each end of the plate attach a copper bus bar. Splash the plate with semi conductive paint. In a very random fashion such that there is not an even coat of paint. Attach power and ground to the opposite bus bars and crank up the voltage. What is going to happen? I suspect at low voltage there will be somewhat even conductance across the plate, but as the voltage increases the current will seek the less resistive path? Until it incinerates that particular path and finds a new one.
     
    Last edited: Mar 22, 2019
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  15. SamR

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    Most of the current in the body is conducted by the electrochemical neurons and synapses of the nervous system which is one reason electrical shock is so damaging the nervous system. Without the electrical stimulation of the musculature the body cannot move. Or the sensory system or the brain or any other organ system work. It's also the reason you "freeze up" when being electrocuted. Military electrical shops used to have wooden walking canes in them to be used as a nonconductive hook to grab someone being electrocuted and pull them off the hot circuit.
     
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  16. WBahn

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    Nope. Until you have so much current that you start changing the properties of the paint, the distribution of current is independent of the amount of current.

    Apply 10 V across the parallel combination of a 1 Ω resistor and a 9 Ω resistor. You will have a total of 10 A flowing with 10% of it in the larger resistor and 90% of it in the smaller. Now make it 10 mV. You will have a total of 10 mA, but the distribution will be the same. As you crank the voltage up eventually you will cause changes in the resistance values -- but the current distribution will then simply be what it is based on the new values.
     
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  17. SamR

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    Mar 19, 2019
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    Yeah I kinda had parallel resistors in back of my mind. Oh well I'm used to how my foot tastes by now. The noticeable effect would be the least resistant path burning up first, but it would all be passing current.
     
  18. jpanhalt

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    Jan 18, 2008
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    Sorry that reference to Bikson's review (post #6) didn't work. I almost always check links I post. For sure, the one time I didn't do that, it was broken.

    Try this link: https://www.researchgate.net/public...ards_associated_with_exposure_to_low_voltages

    Here is a quote from the relevant section:
    John
     
  19. ian field

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    Oct 27, 2012
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    Usually the shortest route...……..
     
  20. Dodgydave

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    Jun 22, 2012
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    As the Skin is the biggest organ in the body, usually it conducts the most electricity under an electriic shock, being the lowest resitstive path...
     
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