Types of Neurons

Author: Scott A. Sheffield MS

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Nerve cells are functionally classified as sensory neurons, motor neurons, or interneurons.

image descriptionSensory neurons (afferent neurons) are unipolar, bipolar, or multipolar shaped cells that conduct action potentials toward or into the central nervous system.

  • They carry somatic nervous system signals from the skin, joints, skeletal muscles, sensory organs (eyes, ears, mouth, and nose). They also carry autonomic nerous system signals from the visceral organs (heart, lungs, vessels, etc).
  • In comparison,  image descriptionmotor neurons (efferent neurons; lower motor neurons) are multipolar shaped cells that conduct action potentials out of the central nervous system.

Learn the anatomy of the nervous system faster and more efficiently with this step-by-step guide full of interactive quizzes and diagrams.

  • Their cell bodies and dendrites are located in the central nervous system and their axons run inside the nerves to the peripheral organs.
  • image descriptionInterneurons(internuncial or association neurons) are the billions of cells that form much of the central nervous system and link the sensory and motor neurons.
  • After receiving input from the sensory neurons, the interneurons perform many complex tasks inside the CNS.
  • First, they integrate, image, and interpret, the sensory information.
  • Next, they form judgments and make needed decisions.
  • Finally, they plan and initiate appropriate response behaviors, which they transfer to the motor neurons.
  • Let’s take a another look at the functional classes of neurons using an illustration that is more anatomically correct.
  • Sensory neurons inside the nerves image descriptionconduct electro-chemical signals (action potentials) from peripheral receptors to the CNS.
  • Brain interneurons process the sensory information, develop a response, and image descriptiondeliver the action plans to motor neurons.
  • The motor neurons image descriptionconduct action potentials out of the CNS to the appropriate peripheral effectors.

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General Structure of a Neuron (Nerve Cell)