Structure Of A Nerve

What Is A Nerve?

The nervous system is formed by the cells and tissues that, in structure, are part of a systematized network having certain grades; it is through these specialized cells that the functions of the body are coordinated and controlled through electricity transferred between them. It further coordinates the integration of sensual information and the activities of muscles, while maintaining homeostasis.

On these grounds, nerves may be considered the conduit through which organs communicate with each other. This is by information on the structure nervous system, functions of the nervous system and functions of nerves in impulse transmission. It also contains information on the various types of neurons and the functions of the neurons.

What Is A Nerve?

Nerves are surrounded by connective tissue sheaths that may conduct electrical impulses between the central nervous system and the peripheries of the body or the organs or muscles in the body system. These are communicated via pathways by which the brain and spinal cord convey information to various parts of the body. They, therefore, become very vital in sensory perception; motor control and coordination of body functions.

The Basic Function Of Nerves

At the most primitive level, the nerves are primarily used for signal transmission from sensory receptors to the central nervous system and from the CNS to muscles and glands. For example, information regarding stimuli such as touch and temperature of the surroundings is carried to the brain with the help of sensory nerves. Mixed nerves have both sensory and motor nerve fibres to provide complete intercommunication between different parts of the body.

Types Of Nerves

• Sensory Nerves: These are afferent nerves, which carry messages from the sensory receptors in the skin, eyes, ears, nose, and tongue through the spinal cord to the brain, which makes it possible for a person to see more light, hear more sound, and feel more touch.

• Motor Nerves: These are efferent nerves, which carry messages from the brain to the muscles and glands in the body to command all sorts of voluntary and.

• Mixed Nerves: Such nerves contain both sensory and motor fibers and, therefore provide two-way traffic communication between the CNS and peripheral tissues.

Anatomy Of A Nerve

The anatomy of the nerve is described below-

Structure Of A Nerve

The detailed structure is explained below:

Neuron:

The aggregation of a large number of axons together forms a bundle; this bundle is covered by several layers of connective tissue to make a nerve. Axons are long, slender projections of the neuron that carry electrical impulses. The structure of the nerve accounts for the effective transmission of signals and also protects the axon from damage.

Detailed explanation of a neuron's structure

The neuron is, in fact, the simplest unit of the nerve, which is in a literal sense carrying the electrical impulse. The major components of the neuron are pointed out in the following lines.

Cell Body—Soma: There lies the nucleus and organelles, and hence it forms the metabolic part of the neuron.

Dendrites: These are the small branches coming out and receiving the signals from other neurons and passing them to the cell body.

Axon: It is the elongated projection that conducts electrical impulses away from the cell body towards other neurons or effector cells.

Myelin Sheath

It is a layer of fat, and thus it insulates the axon. The speed of transmission of impulses thus increases. The Schwann cells produce it in the peripheral nervous system and the oligodendrocytes produce it in the central nervous system.

Nodes Of Ranvier

Gaps between the myelin sheaths. They allow the impulse to travel rapidly and continuously through a process called saltatory conduction.

Axon Terminals

The ends of the axon. Neurotransmitters then spill out into other neurons or muscle cells and communicate with them.

Supporting Structures

The supporting structures are described below-

• Endoneurium: The very thin layer of Connective Tissue surrounding individual nerve fibres within a nerve.

• Perineurium: It is a covering of areolar connective tissue that goes into wrapping each fascicle of nerve fibres. The two main functions are extra protection and adding strength.

• Epineurium: It refers to the outermost connective tissue wrapping layer around the entire nerve. Its main function is to provide some structural integrity and protection.

Types Of Nerve Fibers

The types of nerves are described below-

Classification Based On Diameter And Speed Of Conduction

• Fibres (Alpha, Beta, Gamma, Delta): These are the myelinated nerve fibres of varying diameters and thus have varying conduction velocities. They are ascribed to conduct motor commands and sensory information at a fast pace.

• B Fibers: These are the myelinated fibres of intermediate diameters and conduction velocities. They are responsible for autonomous functions.

• C Fibers: Unmyelinated ones of small diameters with slow conduction velocities that transmit painful sensations and temperature.

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