What subatomic particles do EKG electrodes measure?

[physics_guest]

Hi,

First off, I am new to this forum, so please excuse me if I do not fit in with the norm of this website.

I am an ekg technician. I do many ekg's everyday and was wondering what the heck these electrodes pick up. I understand it is the electric current being measured across the heart. But, I don't understand what subatomic particles are being transferred (if that is what is occurring). Please help me understand if you can. Huge thanks to anyone who answers!

 

[dlgoff]

Welcome to Physics Forums.

EKG machines measure small electrical potentials.

Electrocardiograph (ECG, or EKG [from the German Elektrokardiogramm]) is a transthoracic interpretation of the electrical activity of the heart over time captured and externally recorded by skin electrodes.

http://en.wikipedia.org/wiki/EKG"

 

[berkeman]

Hi,

First off, I am new to this forum, so please excuse me if I do not fit in with the norm of this website.

I am an ekg technician. I do many ekg's everyday and was wondering what the heck these electrodes pick up. I understand it is the electric current being measured across the heart. But, I don't understand what subatomic particles are being transferred (if that is what is occurring). Please help me understand if you can. Huge thanks to anyone who answers!

So to add just a bit to Don's answer. The "subatomic particles" that are moving are electrons, but they don't move very much or very far. The small voltage variations that you see on the different EKG lead traces result from very tiny electrical signals being coupled to the electrodes.

Just as you can use a voltmeter to measure the voltage of a 9V battery, the EKG machine's leads pick up the small voltage variations that are coupled to the skin surface from the electrical activity of the heart's conduction system.

 

[tiny-tim]

welcome to pf!

hi physics_guest! welcome to pf!

… I understand it is the electric current being measured across the heart. But, I don't understand what subatomic particles are being transferred (if that is what is occurring).

more from that wikipedia article …

At rest, each heart muscle cell has a charge across its outer wall, or cell membrane. Reducing this charge towards zero activates the mechanisms in the cell that cause it to contract.​

for details see http://en.wikipedia.org/wiki/Cardiac_action_potential" , including …

The resting membrane potential is caused by the difference in ionic concentrations and conductances across the membrane of the cell during phase 4 of the action potential. … This potential is determined by the selective permeability of the cell membrane to various ions. The membrane is most permeable to K+ and relatively impermeable to other ions. The resting membrane potential is therefore dominated by the K+ equilibrium potential according to the K+ gradient across the cell membrane.​

 

[physics_guest]

Thanks guys! These are all great explanations. I was trying to explain this to my dad, but he was having problems understanding because he wanted to know what "sub atomic particles" are being distributed when a charge crosses the heart. But, I wasn't sure there was a "particle." Seems like it's just a charge. I may ask my physics professor just in case. If there's another explanation, I'll post it. Thanks again.

 

[berkeman]

Thanks guys! These are all great explanations. I was trying to explain this to my dad, but he was having problems understanding because he wanted to know what "sub atomic particles" are being distributed when a charge crosses the heart. But, I wasn't sure there was a "particle." Seems like it's just a charge. I may ask my physics professor just in case. If there's another explanation, I'll post it. Thanks again.

Well, inside the heart there are ions involved in the electrical activity as well. But out toward the skin where you are sensing the AC electrical activity of the heart, it's all electrons.