Central Nervous System

Our bodies would hardly function without the complex network of neurons that is the nervous system. This network helps coordinate our motor activities, our reflexes, actions and sensations. The nervous system can be categorised into two major divisions, chiefly, the peripheral nervous system (PNS) and the central nervous system (CNS).

So what is the central nervous system? The CNS acts as the main processing centre of our body and comprises the brain and spinal cord. Moreover, both these organs are encased in a protective sheath of three layers of membranes. These are called membranes. Furthermore, the brain is encapsulated within the tough and rigid skull, whereas the spinal cord is shielded within the vertebrae or our backbones.

Additionally, a third protective form, called the cerebrospinal fluid, also acts as a buffer between the brain and the skull and between the vertebrae and the spinal cord.

Let us take a deeper look at the central nervous system function and its various parts.

The Brain

The brain is the most complex of the two major central nervous system parts. The outermost portion of the brain called the cerebral cortex houses an estimated 15 to 33 billion neurons, which in turn are connected to other neurons, forming a neural network.

Additionally, the brain is made up of more than 1000 billion glial or support cells and 100 billion neurons. Coupled with the brain, these use up almost 20 per cent of the human body’s total energy.

The brain is roughly divided into three main regions – the forebrain, midbrain and the hindbrain. Together, they comprise four lobes of our brain: the frontal lobe, the parietal lobe, the occipital lobe and the temporal lobe. The largest of these three regions is the forebrain which forms the external layer of the brain. It also consists of the cerebral cortex, and glands such as the pineal, the hypothalamus and the thymus gland.

The midbrain forms the connecting link between the hindbrain and forebrain. It also connects the spinal cord to our brain. The hindbrain is the lower segment of the brain and contains components such as the medulla oblongata, the pons and the cerebellum.

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 Pop Quiz 1

1. What are the Parts of the Central Nervous System?

1. Brain 

2. Spinal cord

3. Frontal lobe

4. All of the above

One significant central nervous system function is the integration of sensory information and the interpretation of our environment. Like an all-knowing processing unit, our CNS helps us to sense and understand what is happening around us with the help of our eyes, ears, nose, tongue and skin. 

Let us read further to find out more about the spinal cord.

The Spinal Cord

Our spinal cords carry sensory information to and fro between the brain and the body and covers the entire length of the back. It meets the brain at the brainstem, from where 31 spinal nerves enter inside the spinal cord. It also forms a connection with the peripheral nervous system, which has nerves spreading across our skin, joints and muscles.

Motor commands in the form of nerve impulses are transmitted from the brain to the muscles, via the spine, comprising yet another essential central nervous system function. The spinal cord contains a complicated mesh of circuits that regulate our reflexes and involuntary actions such as trembling with fear or cold.

Besides the spinal cord, the CNS also consists of an outer layer of grey matter and an inner layer of white matter. Both these tissues are made up of glial cells that help provide support to the neurons. 

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Neurons are the smallest fundamental units of the brain, which helps our bodies to process and transmit information to other organs, glands, muscles and neurons. Each neuron has a cell body called axon and extensions called dendrites.

Rack Your Brains: Consult your teacher or look up some books in the library to learn more about the importance of the central nervous system.

On the whole, the central nervous system is a highly functional and multi-tasking organ system which is unlike most other systems. It controls mostly all kinds of voluntary as well as involuntary actions. It also helps us process our thoughts, our dreams, perceptions and feelings.

For more CNS important questions, check out our broad range of in-depth study material, CNS notes and question papers. You can also download our Vedantu app for better access to these notes, along with online interactive sessions for enhanced clarity.