[Biology Class Notes] on Neuron and Nerves Pdf for Exam

Nerves are individual nerve cells which are a collection of neurons and part of our nervous system. These are located throughout our bodies under our skin, through and around our organs, and towards the centre area of the brain. Neurons are the cells that are present in the nervous system that transmits information to other nerve cells, muscles, or gland cells. The relation between neuron and nerve is nervous tissue is made up of different types of neurons that have an axon and an axon is the long stem-like part of the cell that transmits messages to the next cell.

Difference Between Nerve And Neuron Nerve :

• It is a bundle of axons wrapped by the collective tissues.

• It is covered by three layers perineurium, endoneurium, and epineurium.

• These are found in the peripheral nervous system.

• There are three types of nerves: afferent nerves, efferent nerves, and mixed nerves.

• It is composed of many nerve fibers, blood vessels, and lymphatics.

Neuron :

• It is an individual cell which is the functional unit of the nervous system

• It has three major parts soma, dendrites and an axon

• It is present in both the central and peripheral nervous system

• There are three types of neurons motor neurons, sensory neurons and interneurons

• It is composed of the axon, cell body, and dendrites

Nerve Cell Parts

Nerve cells are also called neurons. It consists of three parts which are as follows:

• Cell Body – It contains the nucleus and other cell organelles. It is also known as (soma) the factory of the neuron. It provides and produces all the proteins for the dendrites, axons and synaptic terminals.

• Dendrites – These are extended from the cell body and receive nerve impulses from other neurons. Dendrites are the antennae of the neuron and covered by a large number of synapses.

• Axon – It is a long extension of the cell body that transmits nerve impulses to other cells. The branches of the axon at the terminal are known as axon terminals. At these terminals, neurons communicate with other cells. Myelin sheath is present in the axon of many neurons as an outer layer. It is a part of the motor neuron.

Working of the Neuron

The basic principle on which a neuron works is an electrically excitable cell that takes up processes and transmits information through electrical and chemical signals. With this,  human beings can react to the environment as neurons transport stimuli. As all neurons are electrically excitable, the impulse mostly arrives at dendrites which are processed into the cell body and then move along the axon. Throughout the length of an axon, it functions as an electric cable by simply transmitting the signal. Once this impulse reaches the end of the axon means synapses a special molecule called a neurotransmitter is released by the neuron. This molecule stimulates the second neuron creating a new wave of electrical impulse. In the end, the impulse reaches the required part.

Different Types of Neurons in the Nervous System 

There are basically three types of neurons which are as follows:

• Sensory Neurons – These are the nerve cells that are activated by sensory input from the environment. Physical and chemical both inputs can activate sensory neurons that correspond to our five senses. Many sensory neurons have only one axon which is split into two branches called pseudounipolar.

• Motor Neurons – These are present in the spinal cord part of the central nervous system which connects to muscles, glands, and organs throughout the body. The impulse from the spinal cord to skeletal and smooth muscles is transmitted through these neurons.

• Interneurons – These are the ones that are present in between which connect the spinal motor and sensory neurons. These form circuits of various complexity while communicating signals between sensory and motor neurons.

Fun Facts

7 trillion nerves are there in the human body.

Neurons are of different shapes and sizes depending on their location.

The body at rest is controlled by the nervous system.

If all the nerves present in the body are lined up they would stretch for almost 45 miles.

Your nervous system is responsible for your ability to perceive your surroundings — to see, hear, and smell what’s around you. In reality, your neurological system is responsible for your ability to wonder how you know where you are! Your capacity to know where you are and recall if you’ve been there previously also suffers.

Your nervous system has a role in your ability to act on information that suggests danger. In addition to allowing you to analyse the threat consciously, your nervous system activates instinctive responses to assist you in coping with danger, such as an increase in heart rate and blood flow to your muscles.

The connecting cells that make up your nervous system are essential to all of these functions. Like the heart, lungs, and stomach, the nervous system is made up of specialised cells. Nerve cells (or neurons) and glial cells are examples of this (or glia). Neurons are the nervous system’s basic functional components, and they generate electrical signals called action potentials that allow them to send information over large distances quickly. Glia is also necessary for nervous system function. However, they primarily serve to sustain neurons.

Though nerve and neuron may sound identical, they are two distinct body parts that are closely related to one another. Nerves are genuine neuron projections.

A neuron is a single specialised cell that is responsible for conveying information via electrical and chemical impulses. They are found in the brain, spinal cord, and peripheral nerves. A nerve
cell is another name for a neuron. Sensory neurons and motor neurons are the two types of neurons. A nerve is made up of several different types of neurons. In the peripheral nervous system, a nerve is an enclosed, cable-like bundle of axons and nerve fibres in the peripheral nervous system. Autonomic nerves, motor nerves, and sensory nerves are the three types of nerves.