Central Nervous System

What is the Central Nervous System (CNS)?

The CNS comprises of the brain and the spinal cord. It is the largest part of the nervous system.

Roles of the CNS
Image4. Central Nervous System

The role of the CNS is to control the parasympathetic and sympathetic pathways. This in turn controls the bodily funtions.

CNS structure
Image5. Structure of the CNS

The brain, also known as the encephalon, is found in the head. It is encased within the protective skull structure.

The spinal cord is found within the spinal cavity which runs along the centre of the back. It is protected by the vertebrae.


What is the meninges?

The meninges is a three layered protective membrane which encloses the brain and the spinal cord.

The three layers starting from the inner most are called: Pia mater, Arachnoid mater, Dura mater.

The Meninges
Image6. The Meninges

Cerebrospinal fluid (CSF) is found in the subarachnoid space (between the arachnoid mater and pia mater layers). The CSF also plays a role in the protection of the CNS.

The CSF is normally clear, however in infectious state the CSF can turn cloudy. The CSF is a good method diagnose infections of the nervous system. The CSF can be obtained via a lumbar puncture procedure.


What is the Blood Brain Barrier (BBB)?

The BBB is the term given to the structure which prevents chemicals and microscopic elements to pass from the blood to the neural tissue of the CNS, whilst allowing substances required for regular metabolic function (i.e. oxygen).

The structure is made up of tight-junctions between the cells which make up the blood vessels carrying blood to the brain. These junctions are responsible for the selectivity.

What is the nervous system?

What is the CNS?
What is the PNS?
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