Neuron And Nerves: Types, Function, Anatomy, Introduction, Difference

Edited By Irshad Anwar | Updated on Jul 02, 2025 06:47 PM IST

The nervous system has two important components: neurons and nerves. Neurons are special cells that carry electrical impulses which allows sensations, movements, and reflexes. Nerves are bundles of neurons through which these signals are transmitted between the brain, spinal cord, and other body parts. Understanding neurons and nerves is the prime topic of Class 11 under the chapter Neural Control and Coordination, and is important for competitive exams like NEET and AIIMS BSc Nursing, where biology is a major subject.

This Story also Contains

Neurons and Nerves
Neuron
Types of Neurons
Neuron Function
What is a Nerve?
Properties of Nerve Fibres
Types of Nerves
Functions of Nerves
Difference Between Nerve Cell and Neuron
Nervous System
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Neuron And Nerves: Types, Function, Anatomy, Introduction, Difference

Neurons and Nerves

Neurons are a class of 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.

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Neuron

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.

Sensory Neurons

They detect external stimuli.
They send information to the CNS.

Motor Neurons

They carry commands to the muscles.
They allow movement and coordination of the body.

Interneurons

Integrate sensory and motor neurons.
Communicate within the CNS.

Neuron Function

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.

What is a Nerve?

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 nerve.

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.

Afferent Nerves

Transmit sensory signals to the central nervous system (CNS).
Play an important role in sensation.

Efferent Nerves

Carry motor signals from the CNS.
Play an important role in involuntary and voluntary movements.

Mixed Nerves

Both sensory and motor fibres are included within the nerve.
They perform the complex functions of the body.

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.

Nervous System

The nervous system is one complex network in the body, used to control and coordinate all activities. It detects changes in the environment, processes information and even activates responses. There are basically two main parts of the nervous system: the Central Nervous System, which 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:

Somatic Nervous System (SNS): Controls all voluntary movements and transmits all sensory information.

Includes the Autonomic Nervous System, which governs actions that a person cannot consciously control, such as their heart rate and digestion, and further divides into the sympathetic (activating the "fight or flight" response) and parasympathetic (promoting the "rest and digest") systems.

The interaction between the CNS and PNS helps integrate the functions of sensory input, motor activities, and vital functions together so that the body can maintain its balance and responsiveness.

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Difference Between Brain and Spinal Cord	Reflex Action and Reflex Arc
Limbic System	Cerebrospinal Fluid

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Frequently Asked Questions (FAQs)

1. What are the functions of neurons?

Neurons are such cells which transmit electrical and chemical signals throughout the nervous system.

2. How do neurons communicate with one another?

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.

3. What are the major types of nerves in the human body?

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.

4. How does a neuron differ from a nerve?

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.

5. What are the treatments for damaged nerves?

It may be in the form of medication, physical therapy, surgical intervention, modification of lifestyle, etc. to alleviate symptoms and to heal the nerves.

6. What is nerve fibre?

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.

7. How do glial cells support neuronal function?

Glial cells, often called supporting cells, play crucial roles in maintaining neuronal health and function:

8. How do neurotransmitter receptors differ, and why is this important?

Neurotransmitter receptors can be broadly categorized into two types:

9. What is the difference between the central and peripheral nervous systems?

The central nervous system (CNS) consists of the brain and spinal cord, while the peripheral nervous system (PNS) includes all nerves outside the CNS. Key differences include:

10. How do neurons change during aging, and what are the implications?

During aging, neurons undergo several changes:

11. What is the concept of neural circuits, and why are they important?

Neural circuits are interconnected networks of neurons that work together to perform specific functions. They are important because:

12. What is the role of ion channels in neuronal function?

Ion channels are crucial for neuronal function as they:

13. What is the role of calcium ions in neuronal signaling?

Calcium ions (Ca2+) play a vital role in neuronal signaling:

14. How do neurons adapt to prolonged stimulation?

Neurons adapt to prolonged stimulation through several mechanisms:

15. How do neurons contribute to memory formation and storage?

Neurons contribute to memory formation and storage through several mechanisms:

16. How do neurons regenerate, and why is this process limited in the central nervous system?

Neurons have limited regenerative capacity, especially in the central nervous system (CNS). In the peripheral nervous system, damaged axons can regrow if the cell body is intact, guided by growth factors and supporting cells. However, in the CNS, regeneration is severely limited due to several factors:

17. What is neuroplasticity and why is it important?

Neuroplasticity refers to the brain's ability to change and reorganize itself by forming new neural connections throughout life. It's important because it allows the brain to:

18. What is the "all-or-nothing" principle in neuronal signaling?

The "all-or-nothing" principle refers to the fact that an action potential either occurs fully or not at all. Once the threshold potential is reached, the action potential will always have the same magnitude, regardless of the strength of the stimulus. Stronger stimuli do not produce larger action potentials; instead, they may increase the frequency of action potentials. This principle ensures reliable and consistent signal transmission in the nervous system.

19. How do neurotransmitters work in synaptic transmission?

Neurotransmitters are chemical messengers released by the presynaptic neuron into the synaptic cleft. They work by binding to specific receptors on the postsynaptic neuron. This binding can either excite or inhibit the postsynaptic neuron, depending on the type of neurotransmitter and receptor involved. The effect can be to open or close ion channels, leading to changes in the postsynaptic neuron's membrane potential. After their action, neurotransmitters are either broken down by enzymes or reabsorbed by the presynaptic neuron in a process called reuptake.

20. What is the difference between electrical and chemical synapses?

Electrical synapses allow direct electrical coupling between neurons through gap junctions, enabling rapid, bidirectional signal transmission. Chemical synapses, which are more common, use neurotransmitters to transmit signals across the synaptic cleft. Chemical synapses are slower but more flexible, allowing for signal amplification, inhibition, and complex information processing. While electrical synapses are always excitatory, chemical synapses can be either excitatory or inhibitory.

21. What is a neuron and why is it considered the basic unit of the nervous system?

A neuron is a specialized cell that transmits electrical and chemical signals in the nervous system. It's considered the basic unit because it's the primary functional component responsible for processing and transmitting information throughout the body. Neurons work together to form complex networks that enable sensation, thought, and movement.

22. How do neurotrophic factors influence neuronal development and survival?

Neurotrophic factors are proteins that promote the growth, survival, and differentiation of neurons. They:

23. How do neurons maintain their polarity, and why is this important?

Neuronal polarity refers to the distinct functional and structural differences between dendrites and axons. Neurons maintain polarity through:

24. What is the role of the axon initial segment in neuronal function?

The axon initial segment (AIS) is a specialized region at the start of the axon that plays crucial roles:

25. How do neurons maintain their energy demands?

Neurons have high energy demands due to constant signaling and maintenance of ion gradients. They maintain these demands through:

26. How do neurons communicate with each other?

Neurons communicate through a process called synaptic transmission. When a neuron is stimulated, it generates an electrical signal called an action potential that travels along its axon. At the synapse (the junction between two neurons), this electrical signal triggers the release of chemical messengers called neurotransmitters. These neurotransmitters cross the synaptic cleft and bind to receptors on the receiving neuron, potentially triggering a new action potential in that cell.

27. What are the main parts of a neuron and their functions?

The main parts of a neuron are:

28. What are the different types of neurons based on their function?

Based on function, neurons are classified into three main types:

29. How do neurons maintain their resting membrane potential?

Neurons maintain their resting membrane potential through the action of ion pumps and channels in the cell membrane. The sodium-potassium pump actively moves sodium ions out of the cell and potassium ions into the cell, creating an electrochemical gradient. Additionally, the cell membrane is more permeable to potassium ions at rest. This combination of active transport and selective permeability results in a negative resting potential inside the neuron, typically around -70 mV.

30. What is an action potential and how is it generated?

An action potential is a brief, all-or-nothing electrical signal that travels along a neuron's axon. It's generated when a stimulus causes the neuron's membrane potential to reach a threshold (usually around -55 mV). This triggers voltage-gated sodium channels to open, allowing sodium ions to rush into the cell, causing rapid depolarization. The membrane potential briefly reverses, then potassium channels open, allowing potassium to flow out and repolarize the membrane. This process creates a wave of depolarization that propagates along the axon.

31. How does the myelin sheath enhance nerve impulse transmission?

The myelin sheath enhances nerve impulse transmission through a process called saltatory conduction. It acts as an electrical insulator, preventing the loss of electrical charge along the axon. The myelin sheath is interrupted at regular intervals by nodes of Ranvier, where the axon membrane is exposed. This arrangement allows the action potential to "jump" from node to node, significantly increasing the speed of impulse transmission compared to unmyelinated axons.

32. What is the significance of the nodes of Ranvier in myelinated neurons?

Nodes of Ranvier are gaps in the myelin sheath along a myelinated axon. Their significance includes:

33. What is the difference between myelinated and unmyelinated neurons?

Myelinated neurons have a fatty insulating layer called myelin sheath around their axons, while unmyelinated neurons lack this covering. The myelin sheath, produced by glial cells, increases the speed of nerve impulse transmission through saltatory conduction. Unmyelinated neurons conduct impulses more slowly but are still essential for certain functions in the body, such as pain sensation and autonomic regulation.

34. What is the role of inhibitory neurons in neural networks?

Inhibitory neurons play crucial roles in neural networks:

35. What is the concept of neuronal ensembles, and how do they relate to brain function?

Neuronal ensembles are groups of neurons that fire together to perform specific functions. Key points include: