Question

What are electrical impulses in the heart?

Answer 1

The electrical impulses is a matter of the movement of ions across a membrane. We are not talking electrical wires like we know, (the transportation of electrons). Some keywords is cellemembranepotential, and the sodium and potassium channels.

Answer 2

whats a potential in heart? whats cellemembranepotential you're talking about?

Answer 3

how are these impulses generated?

Answer 4

This is going to be a long ansewer:

Around cells there is a special environment of molecules and atoms. Some of the molecules/atoms have electrical charges and the ones who are very importent is sodium and potassium. Becuase of the chemical potential (diffusion) this will make a ballance in concentration. Never the less becuase of the charge on the atoms/molecules there is also a electric barrier - a electric potential. The to forces (the chemical potential and the electric potential) will together make a equilibrium, controled by a potential we now define as the electricchemical-potential. This equilibrium will becuase of the concentraion diffrence and charge in the atons/molecules not be ½ on outside and ½ insite. No there is a diffrience so there come a positve charge on the outside of the membrane/cell and a negative charge on the inside of the membrane (fx.) This diffrence between the insite and outside we call the membranepotential is can be seen in the figure i have created (see attachment 1)

Now on the surface of a membrane there is ion channels and the sodium/potassium-pump (Na/K-ATPase) they are able to transport ions in and out. Now some of the ionchannels like the sodium channel is controled by the membranpotential. The higher the membranpotential is the better is the affinity constant (bad said, but lets leave it there). Now imagen we get a impuls from a nervecell the cellemembrane becomes positve, which causes that the sodium-channel opens and can move sodium into the cell. This causes the cell to get a positiv membranepotential and a impuls have been created.

Answer 5

Sorry for all the spelling mistakes.

Answer 6

About the electricchemical-potential then think about Nernst equation.

Answer 7

Ok, that makes things a lot clearer for me..
But what is depolarization and repolarization?

Answer 8

depolarization is when the membranpotential goes from negative to positive. Repolarization the other way around, when it go come positive to negative (the orginal state)

Answer 9

Look at this attachment.

Answer 10

membrane potential goes from negative positive due to the movement of ions?

Answer 11

Is that a part of ECG which im totally confused in?

Answer 12

Heh would be alot more esay if we could talk but yes it is. If you can see a unstable activity they you know there are problems. The mesurement is the voltage by the cellmembrane.

Answer 13

Thanks, I guess I have to process things slowly and hopefully I can get the whole picture soon enough!

Answer 14

You can always write in this question if you find any problem understanding this subject.