Structure of a Neuron

Description: Neurons (nerve cells) are the cells considered to be the basis of nervous tissue. It consists of a cell body, dendrites, and axons. Information flows from the dendrites, which transmits it to the cell body, then down to the axon to its terminal.

Dendrites – A dendrite (tree branch) is where a neuron receives input from other cells.

Cell body – It is also called the soma. It is the spherical part of the neuron that contains the nucleus.

Axon – It is where electrical impulses from the neuron travel away to be received by other neurons

Function: Neurons generate and carry out nerve impulses. It also responds to stimuli, communicates and integrates, provides electrical insulations to nerve cells, and removes debris.

Location: In vertebrate animals, neurons are the core components of the brain, spinal cord, and peripheral nerves.

Five types of Neurons

Description: There are many different types of neurons, and they all have special functions in the brain, spinal cord & muscles that control our body. The five types of neurons are multipolar, unipolar, bipolar, pyramidal & Purkinje.

Multipolar
– It has a single axon and symmetrical dendrites that extend from it. It is responsible for receiving impulses from multiple neurons via dendrites. It is the most common form of neuron in the CNS.

Unipolar
– This neuron has a single axon that is responsible for sending electrical signals. It is usually only found in invertebrate species.

Bipolar
– It has two extensions extending from the cell body and is responsible for sending and receiving information from the world (ex: eyes, nose, and ear).

Pyramidal
– This neuron has one axon but several dendrites to form a pyramid-type shape. It has the largest neuron cells and is primarily found in the cortex.

Purkinje
– This inhibitory neuron has multiple dendrites that fan out from the cell body.

Two types of Neuroglia in PNS

– Neuroglia in the PNS includes Schwann cells & satellite cells.

Schwann cell

Description: It is also known as neurilemma cells, shaped like a rolled-up sheet of paper, with layers of myelin between each coil.
Function: Schwann cells provide myelination to peripheral neurons. They play essential roles in the maintenance, development, process, and regeneration of peripheral nerves. Functionally, they are similar to oligodendrocytes.
Location: Commonly found in close contact with axons in the peripheral nerves.

Satellite Cells

Description: They are small, flattened cells found in the ganglia of the peripheral nervous system
Function: They play an essential role in modulating the PNS following injury & inflammation. They may also help regulate the neuronal environment and be involved in neurotransmission. These resemble the astrocytes of the CNS.
Location: They are found on the surface of neuron bodies in sensory, sympathetic, and parasympathetic ganglia