Neuron Structure and Function

Neurons in human body are the constituents of the nervous system. The neuron diagram shows that they are elongated, and specialized for transmitting electric signals throughout the body. The structure of a neuron consists of a cell body and dendrites. The neurons join together to form the Nervous tissue. The function of neurons is to generate and transmit electric impulses throughout the body. In this article, we will discuss the neuron diagram, meaning, neuron structure, the classification and types of neurons, and neuron function.

Definition of Neuron

Neurons are the fundamental units of the nervous system specialized to transmit information to different parts of the body.

What is Neuron?

The neuron is the basic unit of the nervous system, which helps in the transmission of signals from one part of the body to the other part. Neurons receive and transmit signals to different parts of the body. This transmission process occurs in both physical and electrical forms. The process by which neurons are created is known as Neurogenesis. Neurons can be of sensory type or can be motor in nature.

Neuron Diagram

The neuron diagram class 10 is an important topic in the biology syllabus. Given below is the neuron diagram:

Neuron Structure and Function

A neuron varies in shape and size based on their location. Still, all neurons have three main parts –

• Cell body
• Dendrites
• Axon

Parts of Neuron

The parts of neuron are given below:

Cell Body of a Nerve Cell (Perikaryon)

The cell body of neuron is called Soma or Perikaryon.

• The cell body or soma consists of the nucleus, Mitochondria, Golgi apparatus, pigment granules, Neurofibrils, and Neuro tubules in the cytoplasm that support the neuron.
• The Rough Endoplasmic Reticulum is seen in Nissl granules which extend into dendrites, but is absent in Axon Hillock. Neurons do not contain centrioles, so they cannot divide.
• The plasma membrane of the cell body continues as an axolemma and contains many receptors.

Dendrites

Dendrites are tree-like structures (dendritic trees). They are 2 micrometres in length.

• Dendrites contains ribosomes, smooth endoplasmic reticulum, and Golgi apparatus, useful for high protein synthesizing activity during signal transmission.
• Dendrites are short branching extensions towards Nissl granules
• Dendrites function in neuron by receiving and transmitting signals towards the cell body of the neuron.
• They bear spines which are specialized for contact with other neurons.  

Axon

Axons are long, thin structures which generate and transmit axon potentials, releasing neurotransmitters.

• Axons originate from the Axon Hillock and conduct impulses away from the cell body by their side branches.
• Nissl granules are absent
• Terminal branches have enlarged ends called buttons.
• Peripheral nervous system axons are ensheathed by Schwann cells
• Large axons have a Myelin sheath produced by Schwann cells.
• The Node of Ranvier is a gap between two Schwann cells where myelin is absent and the axon is exposed.
• Central nervous system axons are myelinated by Oligodendrocytes.

Synapse

Synapse is a chemical link that connects the terminal of one neuron and the dendrites of another neuron.

• Synapse function to transmit signals between neurons or from a neuron to a target cell.
• It has a presynaptic terminal and a post-synaptic terminal.
• Electric signals change to chemical signals in the presynaptic neuron end.
• Neurotransmitters bind to receptors on the postsynaptic membrane.
• This triggers an action potential in the postsynaptic neuron or target cell.

Parts of Neuron	Function
Dendrites	Receive messages from other neurons and transmit them to the cell body
Cell Body	Houses the nucleus, Golgi body, endoplasmic reticulum, mitochondria, and other components of the neuron.
Axon	Transmits electrical impulses from the cell body to the axon terminals, which then pass the impulse to another neuron.
Synapse	chemical junction between the terminal of one neuron and the dendrites of another neuron

Types of Neuron

Below are the types of neurons that are classified based on their activities:

Sensory Neuron

• Sensory neurons form the majority of neurons in the body.
• Sensory neuron function to carry information from the sensory receptor cells to the brain.
• These neurons are pseudo-unipolar.
• They quickly relay signals to the brain or nervous system in response to stimuli like stepping on a thorn, conveying chemical and physical inputs.

Motor Neuron

• Motor neurons function to connect the brain to the rest of the body.
• These motor neurons carry the information that the brain produces in response to the information sent by sensory neurons to the muscles or body parts.
• The neurons are multipolar.
•  There are two types of motor neurons: Lower Motor Neuron (travel from the spinal cord to the muscle) and Upper Motor Neuron (travel between the brain and spinal cord).

Interneuron

• Interneuron are multipolar.
• Interneuron transmit data among various neurons in the body and helpconnect the motor and the sensory neurons.
• They also communicate with each other, forming circuits of various complexity.

Neuron Type	Description
Sensory Neuron	Carry sensory information to the brain and quickly relay signals in response to stimuli
Motor Neuron	Transmit signals from brain to muscles
Interneuron	Facilitate communication between different neurons in the body

Classification of Neurons

Based on classification of neuron by structure and function, neurons can be classified into different types. Some of them are:

Neurons Classification based on Function

• Sensory neurons, or Afferent neurons: These conduct impulses from the sensory receptors to the CNS.
• Motor neurons, or Efferent neurons: These conduct impulses from the CNS to the effectors.

Neurons Classified by Structure

According to the number of processes of neurons, they are divided as

• Unipolar Neurons: These show a single process bifurcating into a dendrite and an axon. These are produced by the fusion of two processes of original bipolar neurons. E.g., Cells of the dorsal route Ganglia.
• Bipolar Neurons: Bipolar neurons have one axon and one dendrite. E.g., Bipolar cells of the retina and olfactory mucosa.
• Multipolar Neurons: Multipolar neurons have one axon and multiple dendrites. The majority of neurons in the CNS are multipolar.

What are the Functions of Neuron?

The following are the functions of neurons:

1. Neurons help in transmitting signals that allow comzmunication between different parts of the nervous system.
2. Neurons help integrate signals from multiple sources and then determine whether an action potential will be generated.
3. The sensory neurons intercept signals from the sensory organs and relay them to the brain.
4. The motor neurons, also called efferent neurons, relay signals from the central nervous system to the muscles across the body.
5. Neurons help in maintaining a proper resting potential, which allows for the proper transmission of nerve impulses.
6. A key feature of neurons is the property of plasticity. They are capable of altering their structure in response to experience. This helps with memory function.
7. All body functions are properly coordinated with the help of neurons.

Conclusion – Neurons

Neurons are the building blocks of the nervous system that facilitates the transmission of electric signals throughout the body. They consist of a cell body, dendrites, and an axon, forming nervous tissue. Neurons generate and transmit impulses that helps in communication between different body parts. Neurons are classified based on structure and function. This article explores neuron diagrams, structures, classifications, and functions of neuron, and discuss its vital role in the functioning of human body.

FAQs – Neuron

What is a Neuron? 

Neurons are the basic unit of the nervous system. It is the specialized cell that transfers the information in form of electric signals throughout the body.

What is the Function of Neuron Class 9?

Neurons act as messengers in nervous system, carrying electrical signals called action potentials. These signals transfer between neurons, allowing us to think, move, and react to the stimuli.

How long do Neurons live?

Adult neurons are capable of living through an individual’s lifetime. They are incapable of dividing.

What are Neurons Made of?

The neuron consists of an axon, a dendrite and a cell body. The dendrites help in communication between two neurons.

Which Neuron is Rare?

Bipolar neurons are very rare. They are sensory and are found in the olfactory epithelium, the retina of the eye, and in ganglia of the vestibulocochlear nerve.

What is the Function of Dendrites?

Dendrites receive messages from other neurons and transmit them to the cell body, facilitating communication within the nervous system.

What are the 3 Types of Neurons?

The three types of neurons are sensory neurons, motor neurons, and interneurons.

What is Neuron and its Diagram?

A neuron is a cell specialized in transmitting signals; its diagram depicts structures like the cell body, dendrites, and axon.

What is the Largest Nerve in the Body?

The largest nerve in the body is the sciatic nerve that runs from the lower back down the leg.

What is Neuron Diagram?

A neuron diagram shows the structure of a neuron showing the parts of neurons like dendrites, cell body, and axon.