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Okay, I think we start for today. Welcome everyone.

My name is Stefan Gradl. If you haven't been here last week, I'm basically the replacement for Björn today

because he was in the US and couldn't make it today, so I will give you the lecture.

And unfortunately there are some problems for me as well. I have to go at 3pm.

So either we are finished until 3pm or Felix will do the remaining of the lecture.

But I think it should be possible. So let's see.

Okay, first question. What do you remember from last lecture? What did we do?

What did we talk about? What did Björn tell you? Yes?

We talked about the action potential.

Correct, yes, the action potential. What else?

Yes?

Motor units.

Right, motor units. Where are they?

What do we measure in the motor units? What biosignal? Yes?

The motor.

We talked about the EMG, the action potential and about the EMG.

And also about the electron program.

So first of course was the introduction. What we do in biomedical signal analysis,

what are biomedical signals, and about the action potential, about its key features.

So is there anyone here who can remember anything from the action potential?

At least all the students who went to the exercises should really know it well now.

What's the resting potential, the action potential?

So this is basically a minimum question for the exam, so if you don't know that you will fail for sure.

So you should really know that, and if you repeat it in the lecture and the exercises,

you don't even have to learn it. So what's the resting potential?

Is it minus 100, plus 100 millivolt? Who's for minus 100?

Who is for minus 70? Who's for plus 70?

Okay, of course it's minus 70 to minus 90 millivolts.

And the duration of a normal action potential in a nerve cell, or along a nerve?

How long does it take for the action potential?

Yes?

It's just about one millisecond.

Correct, yes, one millisecond.

And yeah, I don't ask about the depolarization, repolarization process.

Basically it's an exchange of ions, potassium and sodium.

And we also talked about the electromeogram, I don't go into detail about that,

and the electromeogram, which is basically the activity of muscles in the human body.

And you can measure that by placing electrodes on the specific muscles along muscle fibers,

and then just record all the activity in the motor units.

And what you see then in the EMG is basically a summation of all the motor unit activity.

Okay, there were several pathologies that you at least should know one or two of

regarding the electromeogram.

For example, myopathy or neuropathy.

Alright, let's start with this lecture.

We are still in the chapter about generation of biomedical signals.

And today we will talk about maybe the most important,

no, not the most important, but the most known biomedical signal, the electrocardiogram.

It's usually abbreviated ECG, but you can also abbreviate even in English speaking countries with EKG,

so like in German, EKG.