Nerve fibres

In vertebrates, an axon (from Greek v áxn, axis), also known as a nerve fibre (or nerve fibre), is a long, slender projection of a nerve cell, or neuron, that normally carries electrical impulses known as action potentials away from the nerve cell body. Group A nerve fibres, group B nerve fibres, and group C nerve fibres are the three kinds of nerve fibres. Myelinated groups A and B are myelinated, but unmyelinated group C is unmyelinated. Both sensory and motor fibres are included in these groupings. Type I,II,III and IV are four different types of sensory fibres.

Now we will take a deeper look at nerve fibres,how nerve fibres differ from muscle fibres in having dendrites and lastly will take a look at properties of nerve fibres notes.

Nerve fibres-

In vertebrates, an axon (from Greek v áxn, axis), also known as a nerve fibre (or nerve fibre), is a long, slender projection of a nerve cell, or neuron, that normally carries electrical impulses known as action potentials away from the nerve cell body. The axon’s job is to communicate information between neurons, muscles, and glands. 

The axons of certain sensory neurons (pseudounipolar neurons), such as those for touch and temperature, are called afferent nerve fibres, and the electrical impulse travels down them from the periphery to the cell body, and then along another branch of the same axon to the spinal cord. Many hereditary and acquired neurological illnesses have been linked to axon malfunction, which can impact both functions.

Nerve fibres are one of two forms of cytoplasmic protrusions from a neuron’s cell body; dendrites are the other. Axons differ from dendrites in several ways, including shape (dendrites often taper, whereas axons usually maintain a constant radius), length (dendrites are restricted to a small region around the cell body, whereas axons can be much longer), and function (dendrites are restricted to a small region around the cell body, whereas axons can be much longer) (dendrites receive signals whereas axons transmit them). 

Some neurons lack an axon and instead send messages through their dendrites. Axons can emerge from dendrites known as axon-carrying dendrites in some animals.  Although no neuron has more than one axon, invertebrates such as insects and leeches have axons that are made up of many sections that act independently.

How nerve fibres differ from muscle fibres in having dendrites-

First we will read about what we mean by muscle fibre- Muscle fibres are made up of just one muscle cell. They aid in the control of the body’s physical forces. They can help you move your limbs and tissues more efficiently if you combine them together.

 Muscle fibres come in a variety of shapes and sizes, with their own set of features.

Types- Slow oxidative (SO), rapid oxidative (FO), and quick glycolytic muscle fibres are the three kinds of muscle fibres (FG). All three kinds of skeletal muscles are found in varied amounts in most human skeletal muscles. Muscle fibres can also change size or fibre type composition to respond to different demands.

Type 1: Slow oxidative (SO) fibres contract slowly and create ATP by aerobic respiration (oxygen and glucose). They are slow to exhaust and perform low-power contractions over lengthy periods of time.

Type 2 A: Rapid oxidative (FO) fibres have fast contractions and predominantly employ aerobic respiration, but they might exhaust more quickly than SO fibres because they may transition to anaerobic respiration (glycolysis).

Type 2 B: Fast glycolytic (FG) fibres produce rapid contractions and employ anaerobic glycolysis as their primary source of energy. The FG fibres wear down faster than the others.

Coming onto how nerve fibres differ from muscle fibres- Only skeletal muscles have alternate bright and dark bands. Contractile proteins are unique proteins found in muscles. Dendrites are the cytoplasmic extensions of a neuron’s cell body that receive stimulation from neighbouring neurons. Dendrites are found in nerve fibres rather than muscle fibres.

Properties of nerve fibres notes-

1. The nerve fibre is simply a conductor that is very irritable. The dynamic neuronal excitement propagates in waves along it, with bigger axons propagating faster than tiny axons.

2.During excitation, the activity of one segment of the axon acts as a stimulus to activate the next portion, and so on. The electric potential of nerve fibres varies as they become active, with the outside of each active segment becoming negative in comparison to the resting portion.

3.The passage of impulse between active and resting areas is controlled by muscle action currents. The permeability of the axon membrane influences the transmission of nerve impulses, allowing sodium ions to enter and potassium ions to exit the axon.

Conclusion-

So we have learned what we mean by nerve and muscle fibres,their types.Also sensory nerves with receptors sensitive to stretch, tension, and pressure are found in muscles and their tendons. These neurons provide information about muscle dynamics, limb posture, and movement to both conscious and unconscious parts of the central nervous system (proprioception), so in totality it helps in the functioning of the entire body.