Hazardous Voltages

[Tim Cockram]

In message <35230AC3.418F at mr.net>, Mark Amundson <mamundso at mr.net>
writes
>
>To be technically correct, the human heart tends to be centered in the
>chest but the apex of the ventrical (lower) chambers points to your
>lower left side. Tall skinny people tend to have more of a downward
>pointing heart for fairly intuitive reasons. Your brain is the pacing
>device of the heart and is electrically connected to the right atrium
>(upper right chamber) at a place called the sinus node. From there, the
>electrical signal propagates through the heart muscle towards the
>previously mentioned apex. Thus there is a upper right to lower left
>direction of electrical stimulation. An Electro-cardiogram (ECG)
>typically will show three pulses per heartbeat with the middle one being
>greatly taller. The first one is sinus pulse (atrium), followed by the
>large ventricular pulse, followed by a third pulse indicating muscle
>relaxation (refractory).
>
Whoops.  Thanks for the correction Mark.  If I had payed for my course I
guess I should claim a refund.

It was a long time ago, but I'm sure that I remember some literature
relating to relative current flows through the heart, that placed left
arm right leg at the top of the scale (80%?). 

Marks comments re the timing of the shock are the technical reasons why
a residual current breaker can never provide 100% protection.

In the dim and distant past I designed medical equipment including ECG
simulators and an Apple 2 controlled reactive CPR trainer that you could
defibrilate (and did a neat trick if the medic intubated the osophagus
rather than the trachea the dummy would barf).

Regards

Tim




-- 
Tim Cockram