What Is a nurve impulse, And how does it change as it goes through your body?

Answer 1

I guess you are asking about nerve impulses.

This is actually quite a tricky question and doctors and physiologists have to study quite a bit to get it, so I hope I'm putting it into words you can understand.

Firstly - you have a nerve cell and it, in turn has a body (special name is SOMA) and a long tendril or feeler thing called an AXON. It often has many other littler feelers called DENDRITES.

Have a look at the wiki page on nerve cells (or NEURONs)

Okay - so when the neuron wants to send a message down the axon (what determines THIS is even more complex and maybe we'll get to it) it does this by altering the electricity of the axon. I hope you've had a look at the diagram and you can see the axon and the myelin sheath (like insulation around a wire) and the funny nodes of Ranvier which are between each bit of myelin (made by the Schwann cell) and then the axon terminal.

The nerve cell is a cell like many others in your body and it has a membrane. The nerve cell membrane is a little bit different to the membranes of other cells. If you were to magnify it and magnify it you might see something like the picture in the wiki page on Cell_membrane.

Some of the cell membrane proteins (globular red things sticking through both top and bottom) are ion channels and they allow Sodium (Na+) and Potassium (K+) and a few other things to pass through the membrane, which is otherwise water-tight. The sodium and the potassium are salts in the blood and in the cell and all throughout the body - actually they are ions of these salts but this is getting a little too far into tricky chemistry right now.

One of these ion channels pumps the sodium (Na+) OUT of the cell and at the same time pumps the potassium (K+) IN to the cell. This charges the membrane electrically - see the wiki page on Action potential.

When the electricity changes in one part of the membrane, other channels open and allow the Na+ and K+ to swap places and this alters the charge in the next bit of the membrane.

This goes on all the way down the axon until it reaches the axon terminal.

THIS BIT with the electrical impulse and the Na+ and the K+ is the action potential. We can measure it using electrical detectors and probes inside and outside of the cells.

At the axon terminal the nerve cell passes the message along to the next nerve cell across a channel called the SYNAPSE.

This is where neurotransmitters come in and they are released from the end of the axon and go across to start the electricity (or sometimes to suppress the electricity) in the next neuron.

Answer 2

Different types of nerves use different neurotransmitters to convey impulses across the synapses.


See the links below for more in depth information on nerve impulses...