Central nervous system

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The central nervous system (CNS) is comprised of the brain and the spinal cord. It is the 'control centre' for the entire nervous system.


The Spinal Cord

The main role of the spinal cord  is to act as an intermediate between the peripheral nervous system (PNS) and the brain. This can be in the form of sensory information being passed from PNS to the brain or the vice versa, which is in the form of motor information. The spinal cord itself is a runs the whole length of the spine, is a tubular bundle of nervous tissue and support cells called neuroglia. The spinal cord is segmented and each segment has a specific function.

The Brain

The brain receives information from the PNS as well directly from its own integrated nerves such as the optical nerve. It then processes this information and decides upon an appropriate response[1]

Anatomy of the brain

Structually, the brain is heavily folded. Each fold allows the brain to maximise its surface area and thus are present in more complex organisms. Sulci and Fissures are the names of shallow and deep folds respectivly. The brain is split into two hemisphers, left and right. Each hemisphere is responsible for the opposite side of the body and they are connected by the Corpus Callosum, a thick bundle of nerve fibres[2].

The area of the brain which developed most in complex organisms is the Cerebral Cortex and is responsible for higher mental functions. It consists of 4 lobes each with a different function, this is known as cortial specialisation. The frontal lobe is located anterior in respect to the other lobes and is responsible for decision making and planning among other things. The occipital lobe is responsible for processing visual stimuli and is located posterior to the other lobes. The parietal lobe is most superior to the other lobes and is responsible for processing other stimuli such as pain, pressure and touch. Finally the temporal lobe is most inferior to the other lobes and deals with sound stimuli and some memory functions. Sitting inferior to the brain itself is the cerabellum, a 'little brain' responsible for fine motor control[3].

The Limbic system is located deep to the Cerebral Cortex and contains structures such as the Hypothalamus, Hippocampus, Thalamus and Pituitary Gland. This region is responsible for dealing with stresses, danger and desires but also processes such as memory.

Finally the Brainstem is the link between the brain and spinal cord and consists of 3 regions. The Midbrain, Pons and, Medulla. Many vital functions are controled here such as heart rate and breathing[4].

The brain are composed primarily of two broad classes of cells: neurons and glial cells. Glial cells (also called neuroglia) plays an important role in structural support, metabolic support, insulation of nerve axons, and guidance of development[5].


  1. Kimball J. (2013) The Human Central Nervous System.fckLRAvailbale at: http://www.biology-pages.info/C/CNS.html
  2. (Parker et al. The Concise Human Body Book: An Illustrated Guide to Its Structure, Function and Disorders (2009) Dorloing Kindersley Ltc.)
  3. Crash Course (2014) 'Meet Your Master: Getting to Know Your Brain'. Available at www.youtube.com/watch?v=vHrmly4W9C0 fckLR[Last Accessed 26/11/14]
  4. (Parker et al. The Concise Human Body Book: An Illustrated Guide to Its Structure, Function and Disorders (2009) Dorloing Kindersley Ltc.)
  5. Kandel, Eric R.; Schwartz, James H. (James Harris); Jessell, Thomas M. (2000). Principles of neural science. New York: McGraw-Hill.

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