Introduction
Nerves are individual nerve cells which are a collection of neurons and part of our nervous system. These are located throughout our bodies under our skin, through and around our organs, and towards the centre area of the brain. Neurons are the cells that are present in the nervous system that transmits information to other nerve cells, muscles, or gland cells. The relation between neuron and nerve is nervous tissue is made up of different types of neurons that have an axon and an axon is the long stem-like part of the cell that transmits messages to the next cell.
Difference Between Nerve And Neuron Nerve :
It is a bundle of axons wrapped by the collective tissues.
It is covered by three layers perineurium, endoneurium, and epineurium.
These are found in the peripheral nervous system.
There are three types of nerves: afferent nerves, efferent nerves, and mixed nerves.
It is composed of many nerve fibers, blood vessels, and lymphatics.
Neuron :
It is an individual cell which is the functional unit of the nervous system
It has three major parts soma, dendrites and an axon
It is present in both the central and peripheral nervous system
There are three types of neurons motor neurons, sensory neurons and interneurons
It is composed of the axon, cell body, and dendrites
Nerve Cell Parts
Nerve cells are also called neurons. It consists of three parts which are as follows:
Cell Body - It contains the nucleus and other cell organelles. It is also known as (soma) the factory of the neuron. It provides and produces all the proteins for the dendrites, axons and synaptic terminals.
Dendrites - These are extended from the cell body and receive nerve impulses from other neurons. Dendrites are the antennae of the neuron and covered by a large number of synapses.
Axon - It is a long extension of the cell body that transmits nerve impulses to other cells. The branches of the axon at the terminal are known as axon terminals. At these terminals, neurons communicate with other cells. Myelin sheath is present in the axon of many neurons as an outer layer. It is a part of the motor neuron.
Working of the Neuron
The basic principle on which a neuron works is an electrically excitable cell that takes up processes and transmits information through electrical and chemical signals. With this, human beings can react to the environment as neurons transport stimuli. As all neurons are electrically excitable, the impulse mostly arrives at dendrites which are processed into the cell body and then move along the axon. Throughout the length of an axon, it functions as an electric cable by simply transmitting the signal. Once this impulse reaches the end of the axon means synapses a special molecule called a neurotransmitter is released by the neuron. This molecule stimulates the second neuron creating a new wave of electrical impulse. In the end, the impulse reaches the required part.
Different Types of Neurons in the Nervous System
There are basically three types of neurons which are as follows:
Sensory Neurons - These are the nerve cells that are activated by sensory input from the environment. Physical and chemical both inputs can activate sensory neurons that correspond to our five senses. Many sensory neurons have only one axon which is split into two branches called pseudounipolar.
Motor Neurons - These are present in the spinal cord part of the central nervous system which connects to muscles, glands, and organs throughout the body. The impulse from the spinal cord to skeletal and smooth muscles is transmitted through these neurons.
Interneurons - These are the ones that are present in between which connect the spinal motor and sensory neurons. These form circuits of various complexity while communicating signals between sensory and motor neurons.
Fun Facts
7 trillion nerves are there in the human body.
Neurons are of different shapes and sizes depending on their location.
The body at rest is controlled by the nervous system.
If all the nerves present in the body are lined up they would stretch for almost 45 miles.
Your nervous system is responsible for your ability to perceive your surroundings — to see, hear, and smell what's around you. In reality, your neurological system is responsible for your ability to wonder how you know where you are! Your capacity to know where you are and recall if you've been there previously also suffers.
Your nervous system has a role in your ability to act on information that suggests danger. In addition to allowing you to analyse the threat consciously, your nervous system activates instinctive responses to assist you in coping with danger, such as an increase in heart rate and blood flow to your muscles.
The connecting cells that make up your nervous system are essential to all of these functions. Like the heart, lungs, and stomach, the nervous system is made up of specialised cells. Nerve cells (or neurons) and glial cells are examples of this (or glia). Neurons are the nervous system's basic functional components, and they generate electrical signals called action potentials that allow them to send information over large distances quickly. Glia is also necessary for nervous system function. However, they primarily serve to sustain neurons.
Though nerve and neuron may sound identical, they are two distinct body parts that are closely related to one another. Nerves are genuine neuron projections.
A neuron is a single specialised cell that is responsible for conveying information via electrical and chemical impulses. They are found in the brain, spinal cord, and peripheral nerves. A nerve cell is another name for a neuron. Sensory neurons and motor neurons are the two types of neurons. A nerve is made up of several different types of neurons. In the peripheral nervous system, a nerve is an enclosed, cable-like bundle of axons and nerve fibres in the peripheral nervous system. Autonomic nerves, motor nerves, and sensory nerves are the three types of nerves.
FAQs on Neuron and Nerves
1. What is a neuron and what are its main structural parts?
A neuron, also known as a nerve cell, is the fundamental functional unit of the nervous system. It is a specialised cell designed to transmit information to other nerve cells, muscles, or glands. Its three main structural parts are:
- Cell Body (Soma): Contains the nucleus and other essential organelles. It is responsible for producing the proteins needed for the rest of the neuron.
- Dendrites: These are short, branching extensions that receive signals and nerve impulses from other neurons and transmit them towards the cell body.
- Axon: A long, slender projection that carries nerve impulses away from the cell body to other neurons or effector organs. Many axons are covered by a fatty myelin sheath which speeds up signal transmission.
2. What is the fundamental difference between a neuron and a nerve?
The core difference between a neuron and a nerve is one of scale and structure. A neuron is a single cell, whereas a nerve is a bundle of fibres from multiple neurons.
- Neuron: An individual, microscopic cell that processes and transmits electrical and chemical signals. It is found in both the Central Nervous System (CNS) and Peripheral Nervous System (PNS).
- Nerve: A macroscopic, cable-like bundle of axons belonging to multiple neurons, wrapped in protective tissue. Nerves are found exclusively in the Peripheral Nervous System (PNS), connecting the CNS to the rest of the body.
3. How are neurons classified based on their function?
Based on their function in the nervous system, neurons are classified into three main types:
- Sensory Neurons (Afferent): These neurons transmit signals from sensory receptors (e.g., in the skin, eyes) towards the central nervous system (brain and spinal cord). They carry information about stimuli like touch, light, or sound.
- Motor Neurons (Efferent): These neurons carry signals away from the central nervous system to effector organs like muscles and glands, instructing them to respond (e.g., contract a muscle).
- Interneurons: Found exclusively within the central nervous system, these neurons act as connectors, transmitting signals between sensory neurons and motor neurons. They are crucial for processing information and enabling complex reflexes.
4. How does a neuron transmit an electrical signal?
A neuron transmits a signal through an electrochemical process called an action potential. When a neuron is stimulated beyond a certain threshold, it generates an electrical impulse that travels down its axon. This impulse is created by the rapid movement of ions (like sodium and potassium) across the neuron's membrane. Once the impulse reaches the end of the axon, it triggers the release of chemical messengers called neurotransmitters into a tiny gap called the synapse, which then stimulate the next neuron in the chain.
5. Why are the terms 'neuron' and 'nerve' often confused?
The confusion arises because both terms are fundamental to the nervous system and are closely related in function. People often use 'nerve' colloquially to describe anything related to the nervous system's signalling. However, the distinction is critical: a neuron is the individual 'wire,' while a nerve is the entire 'cable' containing many of these wires bundled together. Thinking of a neuron as a single cell and a nerve as an organ-like structure made of many cells helps clarify the difference.
6. How can the relationship between neurons and nerves be compared to electrical wiring?
An excellent analogy is the electrical wiring in a building. In this comparison:
- A single neuron is like an individual copper wire, carrying a specific electrical signal.
- The myelin sheath around an axon is like the plastic insulation around the wire, preventing signal loss and speeding up transmission.
- A nerve is like a thick electrical cable that bundles together many individual wires (axons), all heading in the same direction to power a specific part of the building (a part of the body).
7. What is the precise distinction between a neuron, a nerve, and a nerve fibre?
While related, these three terms refer to different components:
- Neuron: This refers to the entire nerve cell, including the cell body (soma), dendrites, and the axon.
- Nerve Fibre: This term specifically refers to the long, slender projection of a neuron, which is the axon (and sometimes a long dendrite). It is just one part of the neuron.
- Nerve: This is the largest structure, a bundle composed of many nerve fibres (axons) from different neurons, held together by connective tissue.
Essentially, a nerve is made of nerve fibres, and each nerve fibre is part of a neuron.
8. If a neuron is just one cell, how does it contribute to complex actions like thinking or moving a muscle?
A single neuron cannot perform complex actions on its own. The power of the nervous system comes from the immense network these cells form. Complex actions are a result of:
- Neural Circuits: Neurons are connected in vast, intricate circuits. An action like moving a muscle involves signals passing through a chain of sensory neurons, interneurons in the brain or spinal cord for processing, and finally motor neurons.
- Integration of Signals: A single neuron can receive thousands of inputs from other neurons. It integrates these signals—some excitatory (telling it to 'fire') and some inhibitory (telling it to 'wait')—to make a 'decision' about whether to pass the message along. Thinking and consciousness emerge from the coordinated activity of billions of these interconnected neurons.
9. What are the different types of nerves in the peripheral nervous system?
Nerves in the peripheral nervous system are classified based on the direction they carry signals:
- Sensory Nerves (Afferent Nerves): These are composed of axons from sensory neurons and carry sensory information from the body towards the CNS.
- Motor Nerves (Efferent Nerves): These are composed of axons from motor neurons and carry commands from the CNS to muscles and glands.
- Mixed Nerves: This is the most common type of nerve. They contain a mix of both sensory and motor fibres, allowing them to transmit information in both directions.
