Nervous System & Neuron Modeling

       Introduction

The brain is made up of billions of individual nerve cells (neurons).  Neurons are the oldest and longest cells in the body.  One could classify neurons by the number of extensions that extend from the neuron's cell body.  Examples are Bipolar, Unipolar or Multipolar.

        Bipolar neurons have 2 processes extending from the cell body.

        Unipolar cells have 2 axons rather than an axon and dendrite.

        Multipolar neurons have many processes that extend from the cell body.

Another way to classify neurons is by the direction that they send information.

Sensory Neuron

 Sensory Neuron: Sends information from sensory receptors (e.g. in skin, eyes,                             nose &  tongue) TOWARD the central nervous system.

Motor Neuron

 Motor Neuron:  Sends information AWAY from the central nervous system to                            muscles or glands.

Inter neuron

Interneurons:  Send information between sensory neurons and motor neurons.

What is inside of a neuron?

• a neuron has a shaft called an axon and a nucleus inside a cell body.  The axon is lined with myelin sheaths that connect to each other.  There are dendrites on the cell body that receive neurotransmitters released by other neurons.  At the end of the axon, there are little sacs that hold neurotransmitters that are eventually released to send signals to other neurons. 

  The best way to remember the directions of afferent and efferent neuron:

  Remember the difference between afferent and efferent neurons."A"comes before the letter "E" in the alphabet. The stimulus must

  come before the response. The afferent neuron must bring the stimulus

  to the Central Nervous System before the efferent neuron can bring the response from the Central Nervous System. 

  Jabr, Ferris. "Know Your Neurons: How to Classify Different Types of Neurons in the Brain’s Forest | Brainwaves, Scientific American Blog Network." Scientific American Global RSS. 16 May 2012. Web. 8 Mar. 2015. <http://blogs.scientificamerican.com/brainwaves/2012/05/16/know-your-neurons-classifying-the-many-types-of-cells-in-the->.