Neuron Structure and Function

Neurons are the information processing units of the brain responsible for sending, receiving, and transmitting electrochemical signals throughout the body.

Neurons, also known as nerve cells, are essentially the cells that make up the brain and the nervous system. Neurons do not touch each other, but where one neuron comes close to another neuron, a synapse is formed between the two.

These cells develop fully around the time of birth but, unlike other cells, cannot reproduce or regenerate once they die.

1.0Parts of a Neuron

The neuron contains the soma (cell body), which extends the axon (a nerve fiber conducting electrical impulses away from the soma), and dendrites (tree-like structures that receive signals from other neurons). 

2.0Structure of Neuron

1. Dendrites

• Dendrites are the tree-root-shaped part of the neuron which are usually shorter and more numerous than axons. 
• Their purpose is to receive information from other neurons and to transmit electrical signals to the cell body.
• In the central nervous system, neurons are long and have complex branches that allow them to receive signals from many other neurons.

2. Soma (Cell Body)

• The soma, or cell body, is essentially the core of the neuron. 
• The soma’s function is to maintain the cell and to keep the neuron functioning efficiently. 
• The soma contains a cell nucleus that produces genetic information and directs the synthesis of proteins. These proteins are vital for other parts of the neuron to function.

3. Axon

• The axon, also called a nerve fiber, is a tail-like structure of the neuron that joins the cell body at a junction called the axon hillock.
• The function of the axon is to carry signals away from the cell body to the terminal buttons to transmit electrical signals to other neurons. Acting as a conduit, the axon carries these signals to other neurons, muscles, or glands.

• Axoplasm is the cytoplasm within an axon. It is responsible for transporting proteins and other cellular components from the neuron’s cell body to the synaptic terminals and vice versa. 
• This transport is crucial for the maintenance and function of the axon.

• At the end of the axon, synaptic terminals release neurotransmitters, facilitating communication with target cells at specialized junctions called synapses.

3.0Differences between Neurons and other cells

4.0Types of Neurons

On the basis of function :

1. Sensory Neurons: Sensory neurons (sometimes referred to as afferent neurons) are nerve cells that carry nerve impulses from sensory receptors toward the central nervous system and brain.
2. Motor Neurons: Motor neurons (also referred to as efferent neurons) are the nerve cells responsible for carrying signals away from the central nervous system towards muscles to cause movement.
3. Relay Neurons: A relay neuron (also known as an interneuron) allows sensory and motor neurons to communicate with each other. Relay neurons connect various neurons within the brain and spinal cord.

On the basis of Structure:

1. Unipolar neurons: Unipolar neurons, feature a single process extending from the cell body (soma), which is an axon
2. Bipolar neurons: Bipolar neurons bear an oval shaped cell body possessing two processes: one axon and one process functioning as a dendrite.
3. Pseudounipolar neurons: Pseudounipolar neurons consist of one short process, which splits into two other processes.
4. Multipolar Neurons: Multipolar neurons are the dominant type of neurons in vertebrates. They are characterized by multiple processes: a single axon and numerous dendrites.