Possible webpage title: Understanding Voltage Measurements in Biological Systems

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Discussion Overview

The discussion revolves around the principles of measuring electrical potential in biological systems, particularly in relation to the heart and the use of voltmeters. Participants explore the nature of potential measurements, the role of ions and electrons, and the implications for techniques like ECG.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions how a voltmeter can measure potential in biological systems, noting that ions do not flow through electrodes to the voltmeter.
  • Another participant explains that a voltmeter requires only a small current and that charge carriers are typically electrons, which can respond to external electric fields.
  • A participant suggests that redox reactions may occur during ECG measurements, linking the concept of potential to chemical processes.
  • Another participant mentions that voltmeter wires connect two solutions with different ion mixtures, prompting questions about the implications of this setup.
  • One participant notes that measuring voltage on the skin often results in zero volts and emphasizes the need to understand what is being measured.
  • A later reply invites clarification on specific examples that may be causing confusion regarding voltage measurements.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms of voltage measurement in biological contexts, with no consensus reached on the specifics of how ions and electrons interact in this process.

Contextual Notes

Participants highlight the importance of understanding the specific systems being measured and the potential limitations of standard voltmeter readings in biological applications.

Who May Find This Useful

This discussion may be of interest to those studying bioelectrical phenomena, medical instrumentation, or anyone curious about the principles of electrical measurements in biological systems.

thedy
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Hi,What is a physical principle of measuring potential on membrane?
Or on body,if you measure potential of heart.I know,it sounds,like my question is nonsense.But I know,that voltmeter measure potential through free electrons.But for example if I have two clamp on body(eintohoven triangle),we measure potential,which produce heart,but this potential has ion character.And ions doesn t go through electrode to voltmeter.So,how is it possible,that we get a potential.Ions go through wire to voltmeter?

I know,current is flow of particles with charge.But I have studied principle of voltmeter,and if I have understand it correct then if I want to measure potential we have to have flow of current to get result.I know,that potential is between two points and so,but still,if we need to measure potential we must have current flow too.And ions doesn t go like free electrons
Thanks for clarifying...
 
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You know how a voltmeter works? You only need a very small current.
http://en.wikipedia.org/wiki/Voltmeter

It follows that if you are measuring a potential difference with a voltmeter then there are charges flowing ... for a standard voltmeter the charge carriers will be electrons.

The voltmeter leads have lots of electrons which may respond to external electric fields.
The skin (or whatever) will have charges as well, which the electrons will respond to. Ions with a deficit of electrons will accept them and those with a surplus will donate them - none of the ions need flow through the wires themselves.
 
Simon Bridge said:
Ions with a deficit of electrons will accept them and those with a surplus will donate them - none of the ions need flow through the wires themselves.
So,redox reactions are taking place during for example making ECG?
 
Well - the voltmeter wires are weakly connecting two solutions with different mixtures of ions. What normally happens in that situation?
 
So,am I right?Galvanic cell?
 
Depends entirely upon the particular system being measured.

Note:
* usually putting multimeter probes on your skin gives zero volts.
* when there is a "voltage measurement" you have to be careful about what is actually being measured and where.

what I have answered is how there can be a reading on the voltmeter without having exotic ions traveling up the leads.
Perhaps you can provide a specific example of what is puzzling you - stated more clearly?
 

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