Table of Content:
|Neurons||Nerve Fibres – Classification||Nervous System||Frequently Asked Questions|
Though nerve and neuron sounds similar but they are two different components of the body and are closely related to each other. Nerves are actual projections of neurons.
Neuron is an individual specialized cell which are primarily involved in transmitting information through electrical and chemical signals. They are found in the brain, spinal cord and the peripheral nerves. Neuron is also known as the nerve cell. There are two types of neurons – sensory neurons and motor neurons. A group of neurons form a nerve. Neurons are the structural and functional units of the nervous system.
Nerve is an enclosed, cable-like bundle of axons and nerve fibres found in the peripheral nervous system. There are three types of nerves autonomic nerves, motor nerves, and sensory nerves.
Let us know more in detail about the structural unit of the nervous system and nerve fibres.
Nerve Fibres – Classification
The nerve fibre (or axons), is a slender, long, projection of a nerve cell, or neuron, that normally transports electrical impulses called action potentials away from the nerve cell body in vertebrates. The function of the axon is to transmit information between muscles, glands and neurons.
These nerve fibres can be classified into the following types:
- Based on structure – myelinated or non-myelinated nerve fibres.
- Based on origin – spinal or cranial nerve fibres.
- Based on distribution – somatic or autonomic nerve fibres.
- Based on function – sensory or motor nerve fibres.
- Based on the secretion of the neurotransmitter – cholinergic nerve fibres that secrete acetylcholine and adrenergic nerve fibres that secrete noradrenaline
- Based on diameter and conduction of impulse – type A (thickest), type B and type C (thinnest). Type A nerve fibres can be further classified into – type A alpha, type A beta, type A gamma and type A delta.
The neural or nervous system is a complex network of nerve cells or neurons. The nervous system is specialized to carry messages while the endocrine system provides chemical integration through hormones. To better understand the nervous system, one must realize the difference between a neuron and a nerve. Neurons are cells that form the core of the nervous system as they have the ability to receive and transmit signals. They have characteristic elongated shape and consist of three parts:
- Nerve cell body: It consists of the eukaryotic cell components like the nucleus, endomembrane system, and organelles.
- Dendrites: Tiny projections branching out at the neuron’s receiving end, of the nerve cell body. They act like tiny antennas that pick up signals from other cells.
- Axon or nerve fibre: A long, thin fibre that extends from the nerve cell body. It branches at its tips to end in synaptic terminals that are marked by swellings called synaptic knobs. Many axons happen to be insulated by a fatty myelin sheath, which is formed by cells called Schwann cells. Between the Schwann cells, one finds small gaps in insulation called the nodes of Ranvier.
A bundle of axons is termed as a nerve. Nerve signals travel rapidly along the axons of myelinated nerves as the electrical signals tend to hop along the axon from gap to gap, rather than having to flow along the whole axon. Scientists have named this type of nerve conduction the saltatory conduction.
Frequently Asked Questions
What is nerve fibre?
The nerve fibre is a slender, long, projection of a nerve cell, or neuron, that normally transports electrical impulses called action potentials away from the nerve cell body in vertebrates.
What are the properties of nerve fibre?
The two main properties of nerve fibres are – excitability and conductivity.
What are excitability and conductivity?
Conductivity is the ability of nerve fibres to transmit the impulse from the area of stimulation to the other areas. Whereas excitability is the physiochemical change that occurs in tissue when the stimulus is applied.
This is a brief introduction to neuron and nerves. Stay tuned with BYJU’S to learn more in detail about the neuron and nerves along with the YouTube videos.