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Parts of a Neuron and Their Function

Neurons or nerve cells are the basic building blocks or units of the nervous system. Nearly 86 billion neurons work co-ordinately within the nervous system to keep the body in coordination. They are highly specialized cells that act as information processing and transmitting units of the brain. A group of neurons forms a nerve.

What are the Different Parts of a Neuron

Parts of a Neuron Diagram

Although they have a characteristic elongated shape, they vary widely in size and properties based on their location and type of functions they perform.

While they have the common features of a typical cell, they are structurally and functionally unique from other cells in many ways. All labeled neurons include three basic parts: 1) dendrites2) cell body or soma, and 3) axons. Besides the three major parts, there is the presence of an axon terminal at the end of the neuron.

1) Dendrites

Specialized tree-like extensions at the beginning of a neuron that makes possible connections with other neurons. They are highly branched and have small protrusions called the dendritic spines that help to increase the surface area of the cell. Some neurons have very small and short dendrites, while in others, they are very long. Most neurons have numerous dendrites, while in a few of them, there is the presence of only one dendrite.

Functions

  • Acquiring chemical impulse from other cells and neurons
  • Converting the chemical signals into electrical impulses
  • Carrying electrical impulses towards the next part of the neuron, the cell body

2) Cell Body or Soma

Core of the neuron that is similar in structure to any other cell that contains a nucleus, endoplasmic reticulum, mitochondria, Golgi apparatus, and other cellular organelles. The cell body is also the largest part of a neuron enclosed by a cell membrane that protects the cell from its immediate surroundings and allows its interaction with the outside environment. They attach to all the dendrites and thus integrate all the signals. They are metabolically the most active part of the neuron, which contains the genetic material of the cell within the nucleus.

Functions

  • Supporting and organizing the functioning of the whole neuron
  • Joining the signals received by the dendrites and passing them to the axons
  • Synthesizing proteins for other parts of the neuron and thus helping in the normal functioning of the cell

3) Axons

Fine, elongated fiber-like projections that extend from the cell body to the nerve endings of a neuron. They are the longest part of the neuron that can vary widely in size, with some are as short as 0.1 millimeters, whereas others can be over 3 feet long. The bigger the diameter of the axon, the faster they send messages across the neuron. Many neurons have only one axon, which is extensively branched to enable communication with many targets.

Parts of an Axon

Axon hillock – The part of the axon which is attached to the cell body.

Myelin sheath – The layer of fatty acid produced from specialized cells called Schwann cells that are wrapped around the axon.

Nodes of Ranvier – The gaps between the discontinuous myelin sheath that is running along the axon.

Functions

  • Receiving signals from other neurons and directing the outflow of the message to the adjacent connected neurons through (axon)
  • Transmitting neuronal signals away from the cell body towards the next neuron, and also to other muscles and glands by changing the electrical potential of the cell membrane thus generating an action potential (axon and axon hillock)
  • Insulating the axon and thus preventing shock similar to insulated electric wires (myelin sheath)
  • Increasing the speed of the flow of signals within the neuron (myelin sheath)
  • Allowing diffusion of ions in and out of the neuron (nodes of Ranvier)

Connecting Parts of a Neuron: Axon Terminal and Synapse

They are the terminal branches of the axon located at the very end of the neuron. They are also called the axon terminalsynaptic bouton, or terminal button. They are farthest from the soma and contain chemical messengers called neurotransmitters in specialized structures called synaptic vesicles. The small space or gap between two adjacent neurons is called the synapse or synaptic cleftwhich is formed between the axon terminal of one neuron and the dendrites of the next connected neurons.

Functions

  • Releasing of neurotransmitters through specific transport vesicles, called synaptic vesicles from one neuron to the adjacent connected neurons called exocytosis
  • Synaptic vesicles of one neuron for conducting nerve impulse to the adjacent connected neuron through exocytosis
  • Sending neuronal information from one nerve cell to another and also to other cells of the muscle or gland with the help of neurotransmitters
  • Re-up taking of excessive neurotransmitters from the synaptic cleft

Article was last reviewed on Tuesday, January 14, 2020

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