"Brain Cells"

Neurons are responsible for communicating information across the central and peripheral nervous systems using both electrical and chemical signals (*will be expanded on later!!). From the image above, we can identify the different parts of a neuron:

• Cell body (sometimes referred to as the Soma): This is where the nucleus, genetic material and other organelles are located! A lot of neurotransmitters are also produced here, though they can also be produced in the presynaptic terminal (labeled as "Axon Terminal" in the diagram).  

• Dendrites & Axon Terminals: Dendrites are the branchlike formations that come out of the cell body. They go hand in hand with the "Axon Terminal" because throughout our bodies, neurons are usually connected to each other in order to effectively spread messages until they reach the CNS (central nervous system). Specifically, the axon terminals connect to the dendrites. These points of connection are known as synapses (shown in the image to the right).

• Axon: The tail-like projection that goes away from the cell body/soma. and branches out into the axon terminals. 

• Myelin Sheath & Schwann Cells: The myelin sheath is responsible for coating the axon (serving almost like insulation) and making electric nerve impulses (known as "action potentials") travel faster. These electric impulses travel from node (Node of Ranvier) to node much quicker when the axon is properly myelinated. This jumping process is known as "saltatory conduction."

From one Neuron to another

Like we saw earlier, a neuron that precedes a synapse is known as a "presynaptic" neuron, while a neuron that succeeds a synapse is known as a "postsynaptic" neuron. However, the coolest thing here is the space in between, known as the synaptic cleft!! Many actions take place here, but this is also where chemical messages are relayed from one neuron to another (or, if you want to be fancy, "the axon terminals of the presynaptic neuron" to the "dendrites of the postsynaptic neuron")!

Check out the image on the right! The blue blob on the left represents the presynaptic neuron and the purple blob on the left represents the postsynaptic neuron. 

Now, there are two different kinds of synapses: Electrical and Chemical.

Now look at the second image of the two different types of synapses. The image on the right depicts a chemical synapse, hence the neurotransmitters (little blue balls) and receptors (the three purple things on the right blob). Chemical synapses are slower than electrical synapses, because they physically involve the transfer of physical proteins to a variety of receptors that are present on both the presynaptic and postsynaptic neurons (will be covered in more detail later!!)

On the other hand, as seen in the image on the left, in an electrical synapse, signals can go both ways. Unlike in a chemical synapse, the space between two neurons is usually referred to as a "gap junction" and ions are transferred from one neuron to another to change the charges of either neuron, a process known as polarization. 

For extra information or a better definition, check out this fabulous video on synapses by Neuroscientifically Challenged: https://www.youtube.com/watch?v=k5RafiYXieo

Oligodendrocytes ("All-ego-dendro-sites")

Oligodendrocytes are depicted as the little orange popcorn-like cells to the right of the neuron in the diagram above. And just as shown in the image above, one of the main functions of oligodendrocytes is to make myelin, the material that coats/insulates axons and allows impulses to travel faster along nerves. They wrap their projections/branches around axons on neurons within the CNS to produce myelin and contribute to axon insulation. 

Myelin is a fatty tissue made up of mostly lipids and some proteins, which is why it appears white. In fact, white matter (the section of the brain that contains myelinated neurons and allows for fast nerve impluses and signals to travel quickly throughout the CNS) in the brain is white because of all the myelin around the axons of the neurons within it!

As seen in the image to the right, the "gray matter" (the darker pink regions) in the superficial regions of the brain is known as the cerebral cortex and is responsible for thinking/processing and "problem solving," while the white matter is responsible for sending the right signals and information to ensure the thinking and problem solving can happen in the first place. Because most of the neurons in the gray matter regions are unmyelinated, it is the job of the regions with the myelinated neurons ("white matter") to relay signals and information quickly and efficiently.