What Are the Parts of a Neuron?

Sarah Kay Moll
Sarah Kay Moll

Neurons are the primary signaling cells in the brain. There are four parts of a neuron: the cell body, the dendrites, the axon, and the presynaptic terminals. These all work together to send signals across the neuron to other cells.

There are several types of neurons.
There are several types of neurons.

The cell body is where the metabolic functions that sustain the neuron take place. Residing in the cell body is the nucleus, which contains the genetic code. The endoplasmic reticulum, the part of the cell that synthesizes proteins, is also located in the cell body.

Dendrites are one of the parts of a neuron involved in signaling. They branch out from the cell body and form connections with other neurons. The dendrites receive signals from these neurons that change the polarization or electrical charge within the cell.

The cell body of a neuron is known as the soma.
The cell body of a neuron is known as the soma.

The axon is another one of the parts of a neuron that carry electrical signals. It extends from the cell body like the trunk of a tree and carries an electrical charge called an action potential from the cell body to the presynaptic terminals. Axons are coated in a white fatty tissue called myelin, which insulates the cell and allows electrical signals to travel faster. Breaks in the myelin sheath, called nodes of Ranvier, allow the action potential to regenerate.

A neuron usually contains positively-charged potassium ions (+K), while the sodium ions (+Na), also positively charged, reside in the periphery of the neurons.
A neuron usually contains positively-charged potassium ions (+K), while the sodium ions (+Na), also positively charged, reside in the periphery of the neurons.

Where the axon's branches end are called the presynaptic terminals. These terminals extend into the gap between neurons called a synapse. They send chemicals called neurotransmitters across the synapse to other neurons. Usually, the presynaptic terminals communicate with another neuron’s dendrites, but they can also connect to a neuron’s cell body or the beginning or end of an axon.

Dendrites are one of the parts of a neuron involved in signaling.
Dendrites are one of the parts of a neuron involved in signaling.

All the parts of a neuron are polarized, meaning the cell has a different electrical charge than the surrounding area. Typically a neuron is negatively charged at about -65 millivolts (mV), however, this can vary depending on the location and type of neuron. Signals from other neurons can change this charge, making it more positive or negative for a short time.

Multiple sclerosis is marked by the degredation of nerve cells' myelin sheath.
Multiple sclerosis is marked by the degredation of nerve cells' myelin sheath.

Neurons function in essentially the same way, by sending action potentials down an axon and releasing neurotransmitters to communicate to other cells. The meaning of the message is determined by the location and pathway in the brain activated. This means that neurons communicating visual information act the same way as neurons communicating muscle movement, however, their location tells the brain what type of information is being processed.

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Discussion Comments

bluespirit

@Tomislav - Fantastic job. I was just checking myself as well to make sure I wasn't missing any facts on the wonderful world of neurons.

The one area I think you missed slightly on, that your teacher or professor might want you to know on a test is that the cell body contains the nucleus since that is where your genetic code is stored!

Lastly adding to the bigger picture (teachers want their students to know the bigger picture), remember the neuron is a part of the bigger nervous system and that we can thank the neurons for communication within that nervous system.

Tomislav

I am studying for a test so I am trying to rephrase the parts of the neuron. Please let me know if I am forgetting a part! They can be so confusing... in fact I had thought their were only 3 parts of a neuron!

The parts of the neuron and their functions are the cell body which equals metabolism, the dendrites which branch out like a tree and receive signals, the axon which carries electric signals, and last but not least is the presynaptic terminals which extend in the gap between neurons and send chemicals to other neurons.

Think I've got it... anyone care to check me...

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    • There are several types of neurons.
      There are several types of neurons.
    • The cell body of a neuron is known as the soma.
      The cell body of a neuron is known as the soma.
    • A neuron usually contains positively-charged potassium ions (+K), while the sodium ions (+Na), also positively charged, reside in the periphery of the neurons.
      A neuron usually contains positively-charged potassium ions (+K), while the sodium ions (+Na), also positively charged, reside in the periphery of the neurons.
    • Dendrites are one of the parts of a neuron involved in signaling.
      Dendrites are one of the parts of a neuron involved in signaling.
    • Multiple sclerosis is marked by the degredation of nerve cells' myelin sheath.
      Multiple sclerosis is marked by the degredation of nerve cells' myelin sheath.
    • Our bodies contain trillions of synapse "data" connections, many of which are constantly active.
      Our bodies contain trillions of synapse "data" connections, many of which are constantly active.