We are made up out of millions of cells that work together, and so our brains are as well. The cells of our brain are called nerve cells, or neurons. Neurons are special in their function and shape, each of them are grown specifically for their purpose within the brain. There are a lot of different types of neurons, but let’s focus on the basics for now:
A neuron exists of three important components: A cell body, dendrites, and an axon.
The cell body holds the core of the cell, in which all of our DNA is stored (as you can read in this post about genetics). From the central cell body protrude a few root-like spkes, those are the dendrites. The word dendrite comes from the Greek word “Dendron”, which means tree. Like tree-roots, they receive from the environment. Tree roots take in water and nutrients, and dendrites take in information, in the form of electricity. This electricity enters the cell through the dendrites, and moves through the long end to exit through what looks like the tail of the neuron, the axon!
The axon, from the Greek word for axis. The electric signal that entered the nerve cell through the dendrites can now be directed at the next neuron using the axon.
In the image above it kind of looks like someone got a little too excited around the campfire, and used the axon to pierce seven marshmallows. These marshmallows are supposed to be myelin sheets, and in reality they are not this obviously visible. Myelin is a fatty substance that allows the electric signals traveling through the cell, to travel extra swiftly! Myelin also causes the axon to have a white colour.
When we cut the brain in half, crosswise (as in the image on the left) you can see this in that we have grey matter and white matter.
Grey matter contains most of the cell bodies and un-myelinated axons. It covers most of the outside of the brain, and has certain islands more towards the core of the brain.
White matter is on the inside of the brain and is white because it exists of the myelin-covered axons!
The white matter is made up out of bundles of axons, connecting different bases of grey matter to each other. There are different tracts of white matter functioning as high-ways through the brain. The tracts connect grey matter centres with each other so that your entire brain is interconnected. They connect grey matter centres within the same brain half or hemisphere, grey matter centres from different brain hemispheres and also connecting the brain with lower centers down the spine.
In Otter Words: The cells that make up our brain are called neurons. Neurons have specialised parts so that they can communicate with each other at lightning speed! These parts are the base and a tail. The base receives info and the tail passes it on. Our brain is even designed in such a way that the bases are mostly on the outside of the brain and at certain islands on the inside of the brain; this is all grey matter. The tails are organised in pathways within the brain, making up the white matter, and relaying information to every corner of your brain.
In Otter Words 
Joosje, I came to your blog via the meme of the otter wearing a badge with the name Steve on it. I copied that into a journal book in memory of a beloved comrade called Steve. The otter is my totem animal. Then I went to cite the source of the picture so that I could credit you properly. And I am enjoying and learning about neuroscience. Otter breaks things down so that I can grasp the subject. And your life with your brother and family is a inspiration. Thank you for sharing.
On my way to a Zoom meeting with the director of the Jerusalem Princess Basma Centre for Children with Disabilities. (I help raise money for them). Very best, Tracy
Dear Tracy! Thank you so much for your comment, I’m really glad you’re enjoying the blog. I also just found the Otter called Steve from “In Otter News” website – I (unfortunately ;)) did not draw Steve, so maybe look into the crediting again;) However, he did bring you to my “In Otter Words” website. And we’re happy to have you here. I hope your zoom-meeting went well!