EKG Query

[MedStudent219]

Hi all, I'm just really confused about somethings to do with EKGs and I was hoping someone would be able to clarify. From what I understand, when we look at it from the perspective of a single myocardial cell with electrodes on opposite sides: part of it gets depolarised causing the outside to become electronegative while the polarised part has its outside remain positive. If the positive electrode is on the polarised part's outside and negative on the other, then the deflection would be upwards. My question here comes in: my textbook says that the upwards deflection is due to current flowing from negative to positive (i.e. on the outside) and this movement towards the positive electrode causes it to be a positive deflection. Why is it current? I thought the EKG measured voltage or potential difference? (hence the mV units). Really confused and was hoping someone could help. Thanks in Advance!

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[Rocher]

The ekg doesn’t measure current, it measures the electric field generated by the current. The units of electrical fields are V/m, but we just call it volts.

 

[doc05]

There was a really good book about this when I was a student...

 

[CherryRedDracul]

There was a really good book about this when I was a student...

I heard the author was a plastic surgeon who had a fondness for child porn and cocaine.

 

[sella.turcica]

I heard the author was a plastic surgeon who had a fondness for child porn and cocaine.

What's wrong with cocaine?

 

[Hopeful101]

You defs have it wrong...might want to read your ppt again

 

[Psai]

I heard the author was a plastic surgeon who had a fondness for child porn and cocaine.

It's like he's in hollywood

 

[Quantal Reasoning]

When the heart depolarizes, positive ions flood into the cell, leaving the outside relatively negative. the heart doesn't depolarize all at once, so some of the heart is going to be relatively more negative and positive than the other parts. This creates an electric field. An EKG creates its own reference field which is either strengthened or weakened by the hearts created electric field, which is then measured and creates the lines of an EKG.