Neuron Definition, Function, Parts and Diagram

A system that is made up of nerve cells is called Nervous System. The Human Nervous System helps to coordinate the activities of our body. The nervous system serves as the master control system for all our actions, thoughts, and behaviors. Additionally, it facilitates the coordination and harmonious functioning of all other systems within our body. The nervous system works as a manager inside the body, and its job is to control and coordinate body muscles so that we can do things that include reading, cycling, writing, and dancing.

The nervous system also takes care of things we do automatically, like making our heart beat and helping us breathe. The human nervous system is like a messaging system in our body. It receives signals from the environment, interprets them, and then sends out responses to control our actions and reactions. It helps us sense and interact with the world around us.

Neuron: Basic Unit of Nervous System

The neuron is an important part of biology and it is a specialized cell in the nervous system that is responsible for transmitting information through electrical and chemical signals. The neuron is the basic building block of the brain and nervous system. It helps in the communication between different parts of the body and facilitates complex processes such as memory and sensory perception. The Neuron or nerve cell is the unit that makes up the whole nervous system.

The neuron serves as both the structural and functional unit of the nervous system. This means that the nervous system is comprised of multiple specialized cells called neurons. It is the largest cell in the human body which looks like an electric wire. The neuron stands out due to its ability to convey messages in the form of electrical signals referred to as electrical impulses or nerve impulses.

Parts of A Neuron

A neuron is a remarkable structure that is responsible for the transmission of information throughout the body. A neuron consists of several distinct parts, in which each part has its own unique function which helps in the proper functioning of the body. In Biology, a neuron or nerve cell has three components or parts, which are as follows:

1. Cell body or Soma
2. Dendrites (receivers of signals) 
3. Axon (transmitter of signals)
4. Synapses

Cell Body

The cell body of the neuron is like a typical animal cell which consists of a Nucleus (which contains the genetic material DNA and controls the cell activity). The cell body is also known as Soma and is a crucial part of the neuron. It is responsible for maintaining all the functions and metabolic processes of the neuron. The cell body also maintains the health of the neuron and supports its function as a fundamental building block of the nervous system.

Dendrites

A number of long and thin fibers are stretched out from the cell body of the neuron, these long fibers are called never fibers. The shorter fibers on the body of the neuron are called Dendrites. They serve as primary input receivers, responsible for receiving signals from other neurons and transmitting those signals to the cell body. These signals are known as neurotransmitters and are received at special points called Synapses. This Synapsis is the junction where communication between two neurons occurs.

Axon

The axons are the long, slender extension of a neuron that helps to transmit electric impulses away from the cell body. The axon has an insulating and protective cover or sheath of myelin around it (Myelin is made up of fat and protein). At the end of an axon, there are terminal branches that form synapsis with the dendrites of the other neuron. The length of axons can vary from just a few micrometers to over a meter, depending on the location of the neurons in the body.

Synapses

Synapses are the points of communication between neurons. When an electrical signal reaches the synapse, neurotransmitters are released into the synaptic cleft, the tiny gap between the axon terminal of one neuron and the dendrite of another. Neurotransmitters bind to receptors on the receiving neuron, transmitting the signal from one neuron to another, or to an effector cell like a muscle or gland.

Types of Neurons

As of now, it is clear from the above article that both axons and dendrites arise from the cell body of a neuron. Neurons are mainly of three types:

1. Sensory Neuron: These neurons transmit impulses or sensory information from the sensory cells (or receptors) toward the central neuron system (spinal cord and Brain). These neurons play a very important role in helping us respond to our environment, by relaying sensory signals to the brains.
2. Motor neurons: The motor neurons transmit impulses or signals from the central neuron system toward the muscle cells and glands and help in the movement and response of the body. These neurons play a very important role in controlling voluntary and involuntary movements of the body. Motor neurons also help in the regulation of glandular secretion.
3. Relay neurons or Interneurons: Interneurons or relay neurons occur in the central neuron system where they serve as a link between the other neurons, through which the neurons communicate.

Human Neural System

The human nervous system or human neural system is made up of a large number of specialized cells called Neurons. In lower invertebrates neurons are organized in a very simple way, while vertebrates have a more developed neural system. The human nervous system is divided into two parts based on their functions and structures: The Central Neural System and The Peripheral Neural System.

Central Neural System

The central neural system includes the brain and spinal cord, where the brain is the command center of the body while the spinal cord acts as a relay system that transmits signals between the brain and the rest of the body. The central neuron system plays a great role in coordinating voluntary and involuntary actions, sensory perceptions, memory, learning, and regulation of emotions. It receives information from the peripheral neuron system and sends commands to the muscles and organs, which help us to move, think, feel, and respond. It is responsible for transmitting and processing information throughout the body.

Peripheral Neural System

The peripheral neural system consists of nerves and ganglia outside the CNS. The peripheral neuron system consists of a network of nerves that connects the Central Neuron System to the rest of the body, it also helps in the communication between the brain and organs, muscles, and sensory receptors. The Peripheral neural system is further divided into two components: The Somatic Neural System and The Autonomic Neural System.

Somatic Neural System

The somatic neuron system controls all the voluntary movements and sensory perception of the body. It is responsible for the transmission of signals from the sensory organs such as eyes, ears, and skin to the Central Neural System. The somatic neuron system also carries commands from the CNS to the muscles.

Autonomic Neural System

The autonomic neural system helps in the regulation of involuntary bodily functions, such as heartbeat, digestion, and respiration. The Autonomic nervous system is further divided into two branches which are The Sympathetic Neural System and The Parasympathetic Neural System. They are briefly discussed below:

1. Sympathetic Neural System: The Sympathetic Neural System, is responsible for the fight-and-flight response as it prepares the body to respond to stressful situations by increasing the heart rate and increasing the size of the pupil.
2. Parasympathetic Neural System: The Parasympathetic Neural System, works as The Rest- and- Digest System as it promotes relaxation and conserves energy by slowing heart rate and bringing the pupil back to its original size.

Functions of Neuron

Neurons are primarily responsible for transmitting electrical and chemical signals, while they also play many secondary functions in the body.

1. Neurons receive input from other neurons or sensory receptors through their dendrites.
2. Neurons conduct electrical impulses along their axons and allow communication with other target cells.
3. The neurons analyze and interpret the information received, which helps in decision-making.
4. They play a great role in forming and storing memory.
5. Neurons are the motor areas of the brain and spinal cord and control muscle movement.
6. When an electrical or chemical impulse reaches the end of an axon, it releases neurotransmitters, which cross synapses to transmit signals to the next neuron or target cell.

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