Cells of Central Nervous System

Neurons and glial cells constitute parts of the cells of the central nervous system. In addition to sensing changes in their environment, neurons send electrochemical signals to communicate with each other. Neuronal and glial cells offer support, nourishment, insulation, and the removal of metabolic waste. Neuroscientists have believed, for over half a century, that the human brain contains 100 billion nerve cells. The article explains how brain cells work using a new method developed by the neuroscientist Suzana Herculano-Hazel. This method yields a different number – 86 billion brain cells.

About Cells of Central Nervous System 

Let’s list the cells of the central nervous system and their functions:-

1. Neurons

Neurons differ in size, shape, and structure based on their purpose and location. Axons, dendrites, and cell bodies are the three essential parts of a neuron.

Cell body

This is the central section of the neuron, also known as the soma. Neuronal cell bodies contain genetic information, help maintain their structures, and provide energy for the activities of the cells of the central nervous system.

Neurons also have nuclei as well as specialised organelles in their soma. The membrane surrounds and protects it, and allows it to interact with its environment.

Axon

Axons resemble long, tail-like structures. Axon hillocks are specialised junctions between axons and the cell body. An insulating substance known as myelin surrounds many axons. Axons conduct electrical signals with the help of myelin. There is typically only one axon per neuron.

Dendrites

Cell bodies have fibrous roots called dendrites that branch off from the cell body. They receive and transmit signals from other neurons through axons. There are multiple dendrites on some neurons, known as dendritic trees.

Each neuron cell of the central nervous system has a specific number of dendrites depending on the function it performs. There are particular types of neurons in the cerebellum known as Purkinje cells. They can receive thousands of signals via their highly developed dendritic trees.

Schwann cells

Myelinating cells of the PNS and cells that support peripheral neurons are Schwann cells. Schwann cells wrap their plasma membrane around an axon to create a myelin sheath.

Axon Terminal

In the cells of the central nervous system, axon terminals are the button-like ends of axons where the axon connects to another nerve cell or an effector cell. Neurotransmitters are docked at synaptic vesicles at the axon terminal.

2. Glial Cells

Non-neuronal glial cells, also known as glial cells or the neuroglia, are found within the primary nervous system and in the nervous system (peripheral), and provide physical and metabolic support to neurons, including insulating and communicating neurons, and transporting nutrients and waste.

Astrocytes

About half the brain cells are astrocytes; the most numerous type of glial cell.

The primary function of astrocytes, which make up the cells of the central nervous system, is to preserve the conditions for neuronal signalling. They are star-shaped cells found in the brain and spinal cord.

Synapses are controlled by neurotransmitters surrounding them. Neurotransmitter levels in synapses can be sensed by these cells, emitting molecules that influence neuronal activity.

Astrocytes are therefore crucial to the formation and maintenance of synapses and the communication between neurons. Glial cells of this type are accountable to clean up synaptic debris after the synaptic transmission.

Oligodendrocytes

The CNS is also home to oligodendrocytes, another kind of glial cell. They look like balls that have spikes all over them. Shiny, white membranes cover their spike tips. The white membranes are responsible for wrapping around the neuron’s axon. This protective coating over the axon, created by these oligodendrocytes, is known as the myelin sheath.

Microglial

Microglia have a cell body that is oval and has several branches that project from it. These branches help them in transmission. They serve as the first line of defence in the case of brain injury or disease.

Ependymal cells

Epidermis cells are columnar cells discovered in the CNS and commonly arranged into membranes.

Located along the spinal cord and brain ventricles, the respective membrane is termed an ependyma. Cilia, which are hairlike structures on these cells, line the interior spaces of the ventricles. 

What is the most common primary central nervous system (CNS) tumour? 

Conventionally, a central nervous system (CNS) tumour is defined as one that affects the brain or spinal cord. Nevertheless, in the International Classification of Diseases for Oncology, Third Edition (ICD-O-3), tumours in the meninges, pituitary glands, pineal glands, and nerves are classified as CNS tumours. Based on ICD-O-3, brain tumours are defined as tumours of any brain parenchyma. Both brain and central nervous system tumours are included in this report. 

Let’s see more about the most common primary central nervous system (CNS) tumour.

The most common type of CNS tumour is glioblastoma. The incidence of CNS tumours has grown rapidly in recent years. In addition to their mental alteration and neurologic deficits, CNS tumours have a large social burden like other tumours. Therefore, the epidemiology of CNS tumours needs to be accurately understood to facilitate their early detection, treatment, and prevention. 

Many countries have established CNS tumour registries and published descriptive epidemiology. The lack of an accurate national CNS tumour epidemiology makes it difficult to develop policies for early detection and early treatment of tumours. Korea has conducted several trials investigating factors related to CNS tumours. The studies, however, have focused on a small number of cases diagnosed in hospitals. Korea, at that time, lacked national data on CNS tumours.

Conclusion

In the cranial cavity and spinal canal, the cells of the central nervous system, or CNS, are neurons grouped in nerve centres. This system runs along the body’s longitudinal axis. Vertebrates have a brain and spinal cord situated within their cranial cavity and spinal canal. These nerves make up the human body’s central nervous system. The mesencephalon, diencephalon, telencephalon, and medulla oblongata make up the human body’s CNS. And has two main types of cells. This looks after all the functions of the central nervous system.