|MadSci Network: Cell Biology|
The function of a nerve cell, or "neuron" as scientists normally call it, is to carry information in the brain. That information is our sense of the outside world. When you put your hand close to a hot surface (like a stove) one type of nerve cell that stretches from the tip of your finger to your spine can sense that heat. It sends a report of that information into your brain as electricity. When that electrical information has to be shared with another nerve cell in your brain (or spinal cord) it is changed into chemical information between the two cells and then changed back into electricity by the new cell.
The simplest example of the function of nerve cells is the reflex. Using the example of the hot stove, that information about heat is sent to a second nerve cell in your spinal cord that tells the muscles in your arm to move so you pull away from the heat. For an explanation of reflexes with a picture see this page.
There are more complicated examples of neuron function, like the eyes. Deep inside your eye is a layer of neurons that can sense light that you see. They send electrical information into your brain that gets passed between lots of neurons to end up as the scene you see through that eye. Also, your brain can send information out to the rest of your body. Part of your brain that is in charge of moving your arms and legs can send electrical information as a command to the spinal cord. That command is transferred between two neurons in the electrical-chemical-electrical change I mentioned before. The last neuron in the chain then connects to your arm (for example) and might tell it to keep reaching towards the hot stove so you can pick up the pot of boiling spaghetti you are making for dinner.
Try the links in the MadSci Library for more information on Cell Biology.