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

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.

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This Story also Contains

1. Neurons and Nerves
2. Neuron
3. Types of Neurons
4. Neuron Function
5. What is a Nerve?
6. Properties of Nerve Fibres
7. Types of Nerves
8. Functions of Nerves
9. Difference Between Nerve Cell and Neuron
10. Nervous System
11. Recommended Video on Neuron and Nerves

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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• Chemical Control and Integration

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:

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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Recommended Video on Neuron and Nerves