Neuron And Nerves: Types, Function, Anatomy, Introduction, Difference
Neurons are specialized cells that transmit electrochemical impulses, while nerves are bundles of axons that relay signals between the CNS and body. Together, they form the core communication network enabling sensation, movement, and reflexes. This guide covers structure, types, functions, signalling mechanisms, comparison tables, disorders, NEET MCQs & diagrams.
This Story also Contains
- Nervous System Overview
- Introduction to Neurons and Nerves
- Neuron – Structure & Function
- Nerves – Structure & Function
- Difference Between Nerve Cell and Neuron
- Disorders of Neurons and Nerves
- Neuron and Nerves NEET MCQs (With Answers & Explanations)
- Recommended Video on Neuron and Nerves
Nervous System Overview
The nervous system is a complex network in the body that controls and coordinates activities. It detects changes in the environment, processes information and even activates responses. There are basically two main parts of the nervous system:
Central Nervous System: It includes the brain, and the other division, the spinal cord. It makes decisions and is indeed the organ that makes most of the body's controls.
Peripheral Nervous System (PNS): It consists of nerves extending from the CNS to all parts of the body. It has two branches:
Introduction to Neurons and Nerves
Neurons are cells within the nervous system that are responsible for conducting electrical and chemical signals throughout the body. Such impulses permit feeling, movement, and reflexes. Neurons interrelate with other neurons to form networks complex enough to be connected with different parts of the body, including the brain.
Nerves, however, may be defined as bundles of axons, which are the long, slender projections of the neuron covered in connective tissue. They act to provide thoroughfares of communication, carrying signals between the CNS and the PNS. They ensure that the brain gets the sensory information and issues appropriate motor commands to muscles and glands.
Neuron – Structure & Function
A neuron is a special cell in the nervous system. It transmits information through electrical and chemical signals. It has three components: dendrites, which receive incoming signals, a cell body, which processes them and an axon, which sends signals to other cells. Neurons perform various functions, including sensation, movement, and reflexes through communication between different neurons, muscles, and glands.
Structure of Neurons
They have complex, finely detailed structures to better suit efficient signal transmission. Parts of a neuron have individual roles in receiving, processing, and sending information.
Cell Body (Soma)
Contains the nucleus and organelles.
It is central to metabolic activities.
Dendrites
Receive signals from other neurons.
Conduct impulses towards the cell body.
Axon
A long, slender projection.
It carries the impulses away from the cell body.
Synapse
A gap between two neurons.
Neurotransmitters are released here.
Types of Neurons
The types of neurons are classified based on their function and the direction of transmission of the signal.
Types of Neurons | Description |
Sensory Neurons |
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Motor Neurons |
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Interneurons |
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Functions of Neurons
Neurons use electrochemical signals to communicate. This is carried by ions moving in and out of the cell, thereby allowing very rapid transmission of information through the nervous system.
Electrical Signaling
Generation of action potential.
Propagation down the length of the axon.
Chemical Signaling
Release of neurotransmitters.
Transmission across the synapse.
Nerves – Structure & Function
A nerve is defined as a bundle of fibres made up of many neurons that transmit signals between the brain, spinal cord, and the rest of the body. Nerves carry sensory information to the brain and send motor commands from the brain to muscles and organs that help create sensations, movement, and functions in the body.
Structure of Nerves
Nerves are protected and supported internally to allow efficient and reliable transmission of the axons within them.
Epineurium
Outer, protective connective tissue sheath.
Protects nerves.
Perineurium
Surrounds fascicles (groups or bundles of nerve fibres).
Holds structure.
Endoneurium
Encloses individual nerve fibres.
Maintains insulation.
Properties of Nerve Fibres
The main features of nerve fibres are:
The ability to respond to stimuli and to generate impulses.
The ability to transmit impulses down the fibre.
A temporary state immediately after an impulse that does not permit return flow.
The response is full if the stimulus exceeds a threshold; otherwise, no response at all
The response to steady stimuli diminishes over time.
Impulses are transmitted faster by myelinated fibres than by unmyelinated ones.
Types of Nerves
Nerves are classified based on function and also on the direction of signal transmission, similar to neurons.
Types of Nerves | Description |
Afferent Nerves |
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Efferent Nerves |
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Mixed Nerves |
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Functions of Nerves
Nerves play an important role in the maintenance of the body's functioning by transmitting signals and in reflex actions.
Signal Transmission
Allow effective communication at very high speeds.
Comprise physiological responses of the body.
Reflex Actions
Immediate involuntary responses to a stimulus.
Prevent damage to the body.
Difference Between Nerve Cell and Neuron
The major difference between nerve and neuron are:
Aspect | Neuron | Nerve Cell |
Definition | The specialized cell that transmits signals in the nervous system. | Any cell in nerves, including neurons and supportive cells. |
Function | Processes and transmits information via electrical impulses. | Supports nerve structure and function, and may or may not transmit signals. |
Types Included | Only neurons (sensory, motor, interneurons). | Includes neurons and glial cells (support cells). |
Primary Role | Active communication in the nervous system. | Can support, insulate, or protect neurons. |
Disorders of Neurons and Nerves
Different disorders have been associated with neurons and nerves and are responsible for various signs and symptoms, which may further affect functions.
Neuropathy
Nerve injury and its effects.
Its symptoms, causes, and diagnosis.
Multiple Sclerosis
Directed autoimmune disorder towards myelin.
Nerve transmission of the signal.
Amyotrophic Lateral Sclerosis (ALS)
It causes progressive degeneration of the motor neurons.
Control and movement of muscles are affected.
Neuron and Nerves NEET MCQs (With Answers & Explanations)
Important questions asked in NEET from this topic are:
Structure of neurons and nerves
Types of neurons of nerves
Neurons vs Nerves
Practice Questions for NEET
Q1. The major constituents of neurofilaments are
Microtubules
Intermediate filaments
Actin filaments
Protofilaments
Correct answer: 2) Intermediate filaments
Explanation:
The main structural element in the neurons of the brain is neurofilament. They are fibrous proteins having a diameter of 10 nm.
The proteins involved as structural elements in the neurons are divided into six types based on protein structure and gene organization. Neurofilaments are classed as Type IV intermediate filaments which are found in the cytoplasm of neurons. Neurofilaments majorly consist of intermediate filaments. They provide the structural support for axons as well as regulate the diameter of the axons. These intermediate filaments are also found in cyton and dendrites and transmit nerve impulses.
Hence, the correct answer is option (2) intermediate filament.
Q2. Myelinated nerve fibres are found in
Spinal nerves
Cranial nerves
Autonomic nervous system
Both a and b
Correct answer: 4) Both a and b
Explanation:
There are two types of axons, namely, myelinated and unmyelinated. The myelinated nerve fibers are enveloped with Schwann cells, which form a myelin sheath around the axon. The gaps between two adjacent myelin sheaths are called nodes of Ranvier. Myelinated nerve fibers are found in spinal and cranial nerves. Unmyelinated nerve fiber is enclosed by a Schwann cell that does not form a myelin sheath around the axon and is commonly found in autonomous and somatic neural systems.
Hence, the correct answer is option 4) Both a and b.
Q3. Nerve fibers are surrounded by an insulating fatty layer called
Adipose tissue
Myelin sheath
Hyaline sheath
Peritoneum
Correct answer: 2) Myelin Sheath
Explanation:
The myelin sheath is an insulating fatty coating that envelops nerve fibers. By enabling electrical impulses to leap between the Nodes of Ranvier, which are openings in the myelin sheath, the sheath speeds up the transmission of nerve signals. Saltatory conduction is the mechanism that speeds up and improves neuron transmission.
Hence, the correct answer is option 2) Myelin sheath.
Also Read:
Recommended Video on Neuron and Nerves
Frequently Asked Questions (FAQs)
A nerve fibre is a long, thread-like extension of a neuron, referring to the axon, which transmits electrical impulses. It is responsible for carrying signals between neurons, muscles, and organs in the body.
They communicate via synapses where neurotransmitters are released from one neuron that binds to receptors on the next neuron, which relays or transmits the signal.
Sensory signals are carried from it to the CNS by afferent nerves, and motor signals from the CNS by efferent nerves, while mixed nerves are served by both sensory and motor fibres.
A neuron is one cell that transmits the signal, while the nerve is a cluster of the axons of several neurons, acting merely as a pathway for the transmission of signal.
It may be in the form of medication, physical therapy, surgical intervention, modification of lifestyle, etc. to alleviate symptoms and to heal the nerves.
Neurons are such cells which transmit electrical and chemical signals throughout the nervous system.