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Bumpy Activity Book
Bumpy Brains Activity Book



Cells of the Nervous System:

Neurons
Glial Cells




Course Topics:

Nervous System
Neurons & Glial Cells
Brainatomy

The Structure of a Neuron
Guest starring Nestor the Neuron!

Each part of Nestor has been labeled.  Below are the descriptions for his parts:

Soma (cell body): contains cytoplasm, the nucleus and other organelles such as mitochondria. 

Nucleus: contains DNA.

Dendrites: receive information from other neurons (known as pre-synaptic neurons).  Dendrites receive information through receptors.  Receptors are also found on the cell body.

Dendritic branch: a branching of the dendrite; also contains receptors.

Axon hillock: connects the soma to the axon

Axon: carries information to other neurons (known as post-synaptic neurons).

Myelin sheath: made up of lipids and proteins, myelin electrically insulates the axon.  The purpose of myelin is to speed electrical impulses (information being to sent to post-synaptic neurons or other non-neuronal cell) down the axon.

Nodes of Ranvier:  gaps between segments of myelin sheath.  Electrical impulses jump from one node to the next (over the fatty myelin sheaths), thus speeding the impulse (this is called saltatory conduction). 

Schwann cell:
in the peripheral nervous system, a type of glial cell that provides myelin to axons.  In the central nervous system, oligodendrocytes provide myelin.

Terminal button: also known as the axon terminal; the end of the axon.  This is where the impulse finally ends and information is transmitted via the release of neurotransmitters.

Neurotransmitters: "chemical messengers" that allow neurons to communicate with each other.

Neurons are also known as "brain cells,"  and are a type of cell that make up the nervous system (along with glial cells).  They are responsible for everything we do, including walking, talking, eating, sleeping, and thinking! 

Neurons differ from other cells in the body because they have an axon and dendrites which allow them to send and receive information to and from other neurons.


Note: the nervous system is comprised of the central nervous system (the brain and spinal cord) and the peripheral nervous system (somatic and autonomic nervous sytems).



The Structure of a Neuron: Simplified by Vinny

Vinny's Neuron
neuron
cells in NS that communicate
dendrites
receive information
soma
cell body; has DNA and other stuff like mitochondria
axon
sends information
myelin sheath
wraps around axon (it's really made of oligodendrocytes!); speeds up information sending and insulates those messages (because they're electric)




Try it!
Put Vinny's neuron back together.  Click and drag the structures (to the right) onto the outlined neuron (on the left).

Vinny's Neuron Outline
Dendrites
Vinny's Dendrites
Axon
Vinny's Axon
Soma

Vinny's Soma






Myelin Sheath
Vinny's Myelin Sheath




The Synapse

A synapse is where a neuron communicates with a post-synaptic neuron or other non-neuronal cell.  A synapse includes 3 parts:


  1. Terminal button (axon terminal) of pre-synaptic neuron.
  2. Synaptic cleft (space between the cells).
  3. Dendrites or membrane of the post-synaptic neuron or other cell.
Depending on the type of signal, synapses can either be electrical or chemical.


NT Synapse




Glial Cells
Glial Cells 1

Glial cells
, along with neurons, make up the Nervous System.  There are different types of glial cells, including:


  • Astrocytes - give structure and nutrients for neurons (pictured left)
  • Microglia - clean up the trash in the nervous system (pictured left)
  • Oligodendrocytes - make up myelin in the CNS (pictured below)
  • Schwann cells - make up myelin in the PNS (pictured below)
The drawing to the right shows that oligodendrocytes wrap around axons of many different neurons and schwann cells wrap around only one axon.

Here is a comic of this drawing (rated PG-13).
Oligodendrocyte and Schwann


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