Name: how neurons send signals
Uploaded: 2025-10-23T11:49:29.000Z
Duration: 1 min 31 s
Channel: JoVE

Neurons are the cells of the nervous system that transmit electrical signals. They come in a variety of shapes and sizes but generally have some common features. All neurons have a cell body, also called the soma, that contains the nucleus. Most neurons also have dendrites and an axon that extends from the cell body.

Dendrites are often highly branching and they receive signals from other neurons at junctions called synapses. The axon, on the other hand, transmits signals to neurons and other cells. The axon hillock, where the cell body meets the axon, generates the action potential, the primary form of electrical signaling in the nervous system.

Axons are often wrapped in a fatty myelin sheath, made by support cells called glia, which insulates them, helping to maintain the electrical signal as it is transmitted along. The nodes of ranvier, gaps in the myelin sheath, are regions where the action potential is repeatedly regenerated down the axon.

At the end of the axon is the terminal, containing synaptic vesicles filled with neurotransmitter molecules. When an action potential reaches the terminal, neurotransmitter is released into the synaptic cleft, a region of space between cells at a synapse. Depending on the type of channel, the neurotransmitter can help transmit the signal to the next cell.

neuron structure

<h4>Overview</h4>

Neurons are the main type of cell in the nervous system that generate and transmit electrochemical signals. They primarily communicate with each other using neurotransmitters at specific junctions called synapses. Neurons come in many shapes that often relate to their function, but most share three main structures: an axon and dendrites that extend out from a cell body.

<h4>Structure and Function of Neurons</h4>

The neuronal cell body&#8212;the soma&#8212; houses the nucleus and organelles vital to cellular function. Extending from the cell body are thin structures that are specialized for receiving and sending signals. Dendrites typically receive signals while the axon passes on the signals to other cells, such as other neurons or muscle cells. The point at which a neuron makes a connection to another cell is called a synapse.

Neurons receive inputs primarily at postsynaptic terminals, which are frequently located on spines&#8212;small bumps protruding from the dendrites. These specialized structures contain receptors for neurotransmitters and other chemical signals. Dendrites are often highly branched, allowing some neurons to receive tens of thousands of inputs. Neurons most commonly receive signals at their dendrites, but they can also have synapses in other areas, such as the cell body.

The signal received at the synapses travels down the dendrite to the soma, where the cell can process it and determine whether it should send the message forward or not. The action potential is the main electrical signal generated by neurons. It carries the information forward onto the next cell. It is first generated at the axon hillock&#8212;the junction between the soma and the axon.

Axons vary in length but can be quite long. For example, some extend from the spinal cord all the way to the foot. Longer axons are usually wrapped in a fatty myelin sheath that insulates the axon, helping to maintain the electrical signal. The myelin sheath is created by glia&#8212;another type of cell in the nervous system. In myelinated axons, the action potential is regenerated at each node of Ranvier&#8212;repeated gaps in the myelin&#8212;until it reaches the terminal at the end of the axon, or presynaptic terminal.

The presynaptic terminal has vesicles that contain pools of neurotransmitters. Action potentials trigger the vesicles to undergo exocytosis by fusing to the cell membrane and releasing neurotransmitter into the synaptic cleft&#8212;the gap between cells at a synapse. Different neurotransmitters can have varying effects on the postsynaptic cell. An excitatory synapse increases the chances of initiating an action potential on the postsynaptic cell, while an inhibitory synapse decreases the chances of an action potential.

<h4>Neuronal Morphology</h4>

The overall shape of neurons&#8212;their morphology&#8212;can vary dramatically and often relates to their function. Some neurons have few dendritic processes and a single axon, others have very convoluted dendritic arbors, while others have axons that can span the length of the organism. The diverse morphologies are often used to define the type of neuron. The number of inputs&#8212;synaptic connections&#8212;can influence how a cell responds to signals. Therefore, the morphology of the dendrites, and the number of synapses they contain, is an important feature that can determine the type of neuron. In the peripheral nervous system, the dendrites can also define the receptive field of a cell&#8212;the physical space on the body that they are sensitive to.

<h4>The Art of Visualizing Neuronal Structures</h4>

The Spanish anatomist Santiago Ramon y Cajal, working in the late 19th and early 20th century, pioneered the tracing of individual neurons and provided fundamental insights into their very nature. He produced stunning depictions of cells that still offer a considerable amount of detail. Using the staining technique developed and named after the Italian biologist Camillo Golgi, he was able to trace the structure of many different kinds of cells in the brain. He also sketched some of the basic connections of neuronal circuits&#8212;networks of neurons that are activated together to process specific information.

Neuron Structure

Overview

Neurons are the main type of cell in the nervous system that generate and transmit electrochemical signals. They primarily communicate with each ...

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how neurons send signals

Neurons send signals through a clear set of structures that let them receive, process, and pass on information. They are the main cells of the nervous system and use electrochemical signals to communicate. Neurons also talk to other cells through neurotransmitters at junctions called synapses.

Most neurons share three main parts: a cell body, also called the soma, dendrites, and an axon. The soma holds the nucleus and other organelles needed for cell function. Dendrites usually receive signals, while the axon carries signals onward to other neurons or to muscle cells.

Neurons receive input mainly at postsynaptic terminals, which are often found on small bumps called spines on dendrites. These spines contain receptors for neurotransmitters and other chemical signals. Because dendrites can branch a great deal, some neurons can collect tens of thousands of inputs. Neurons can also have synapses on other parts of the cell, such as the cell body.

Signals that arrive at synapses move down the dendrite to the soma. The cell then processes the message and decides whether to pass it on. If it does, the main electrical signal, called an action potential, starts at the axon hillock, the junction between the soma and the axon.

Axons can vary in length and may be very long. Some extend from the spinal cord all the way to the foot. Longer axons are often wrapped in a fatty myelin sheath, which insulates the axon and helps keep the electrical signal going. Glia, another type of nervous system cell, make the myelin sheath.

In myelinated axons, the action potential is regenerated at each node of Ranvier, which is one of the repeated gaps in the myelin. The signal continues this way until it reaches the presynaptic terminal at the end of the axon. That terminal contains vesicles filled with neurotransmitters.

When an action potential arrives, the vesicles fuse with the cell membrane and release neurotransmitters into the synaptic cleft, the gap between cells at a synapse. Different neurotransmitters can affect the postsynaptic cell in different ways. An excitatory synapse makes an action potential more likely, while an inhibitory synapse makes it less likely.

Neuron shape, or morphology, can vary a lot and often matches function. Some neurons have few dendritic processes and one axon, while others have highly branched dendritic trees or axons that span the length of the organism. Scientists often use these shapes to help define neuron types.

The number of synaptic connections also affects how a cell responds to signals. For neurons in the peripheral nervous system, dendrites can help define the receptive field, which is the physical area of the body that the cell senses. The form of the dendrites and the number of synapses they contain are important clues about neuron function.

The study of neuron shape was advanced by Santiago Ramon y Cajal in the late 19th and early 20th century. He traced individual neurons and made detailed drawings that still show a great deal of information. Using the staining method developed by Camillo Golgi, he was able to map many cell types in the brain and sketch basic neuronal circuits, which are networks of neurons that work together to process specific information.

How Neurons Send Signals

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Neurons send signals through a clear set of structures that let them receive, process, and pass on information. They are the main cells of the nervous system and use electrochemical signals to communicate. Neurons also talk to other cells through neurotransmitters at junctions called synapses. Most neurons share three main parts: a cell body, also called the soma, dendrites, and an axon. The soma holds the nucleus and other organelles needed for cell function. Dendrites usually receive...

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key terms and concepts

Learn how neurons receive, process, and transmit signals through dendrites, axons, myelin, synapses, and neurotransmitters in this high school science page.

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How Neurons Send Signals

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