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All About Neurons
When studying the brain, one of the key parts to focus on is the neuron, which is the cell of the nervous system. Like other cells in the brain, the neuron carries out basic cellular functions; however, neurons have unique function, like sending the electrical signal through the brain. This study guide will go over the different types of neurons, the parts of a neuron, and what their functions are.
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Types of Neurons
When discussing neurons, remember there are three functional types of neurons: sensory neurons, motor neurons and interneurons. Let's go over how each of them works:
- Sensory neurons: these neurons get sensory information from your body, such as pain or temperature. The neurons then send the information to the central nervous system, which is why they are also called afferent neurons.
- Motor neurons: these neurons send the information to your muscles, telling them to move when something hurts or if the stove is hot. The neurons relay the information from the nervous system system, which is why they are also called efferent neurons.
- Interneurons: these neurons act as a relay between the sensory and motor neurons.
When studying the structure of the neuron, note that it does not always follow the unipolar neuron layout: dendrites → soma → axon → terminals. Besides unipolar neurons, the brain houses three other formations: bipolar neurons, pseudounipolar neurons and multipolar neurons. Let's go over how their structure differs from unipolar neurons:
- Bipolar neurons: these neurons have two extensions from the soma.
- Pseudounipolar neurons: these neurons have two axons, with the soma as an off-shoot
- Multipoloar neurons: these neurons have one axon, but multiple extensions
Use the images in the gallery below when studying these three formations types of neurons.
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Parts and Function of a Neuron
When going over the different parts of the neuron, use a unipolar neuron: this will minimize any confusion that can arise from using a multi-extension neuron. Next to each number on the neuron, write down the name of the structure, and what it does:
- Dendrite: this gathers the electrical signal from another neuron
- Axon: the “tail” of the neuron; the electrical signal travels down it
- Nodes of Ranvier: parts of the axon not covered in myelin sheath; the electrical signal “jumps” here
- Axon Terminals: the end of the axon, where the electrical signal is transported to the next neuron; also called the presynaptic terminal
- Myelin Sheath: a protective coating on the axon made of oligodendrocytes, a type of glial cell; prevents the electrical signal from losing strength
- Cell Body (Soma): the “head” of the neuron
- Nucleus: like in other types of cells, the nucleus contains the genetic material
Practice drawing your own neuron, and try labeling the other structural types of neurons.
- Image Credit: Neuron by NickGorton under CC by -SA 3.0
- University of Washington: Types of Neurons, http://faculty.washington.edu/chudler/cells.html
- Image Credit: Bipoloar, Pseudounipolar and Multipolar Neurons by Elizabeth Stannard Gromisch. All rights reserved.
- University of Washington: Action Potential, http://faculty.washington.edu/chudler/ap.html