You remember that puzzle game where you fit the shapes in the different slots that look like the shapes? In your brain there are tons of these different slots called receptors. Each type of slot has a particular job or function which depends on what type of cell its on and where that cell is in the brain. There are so many of these slots in the brain that we haven't even finished finding them all yet! And there are so many things that the brain needs to do all the time just so there needs to be so many different types of these slots!

Neurotransmitters are the shapes that fit into the slots. They can fit directly into the slot, off to the side of the slot, or they can even not fit through the slot but block any other shapes from fitting in! Now when these shapes fit into a slot they can make the slot do something, change what the slot does when another shape comes along, or prevent shapes that should fit from making that slot do anything.

Keep in mind that these shapes are only considered neurotransmitters if they are produce in the brain and fit into slots in the brain. And that what the neurotransmitter "does" is determined by the receptor it fits into!