The Nervous System

What makes us tick?  Hopefully, there aren’t too many “nervous ticks” involved, but the nerves are central to who we are.  They are signal pathways and, when combined into interwoven bundles, are control centres.

A few days ago a gentleman, who was giving our company an interesting talk on the harmful effects of drugs and alcohol on performance, asked for a few details of the nervous system.  So, I thought a simplified summary of the whole nervous system (both Central and Peripheral) could be just the ticket…

The Nervous System

The Nervous System is your body’s decision and communication centre. The Central Nervous System (CNS) is made up of the brain and the spinal cord whereas the Peripheral Nervous System (PNS) is made up of nerves (neurons). Together they control every part of your daily life, from breathing and blinking to helping you memorize facts for a test. Nerves reach from your brain to your face, ears, eyes, nose, and spinal cord… and from the spinal cord to the rest of your body. Sensory nerves gather information from the environment, send that info to the spinal cord, which then speed the message to the brain. The brain then makes sense of that message and fires off a response. Motor neurons deliver the instructions from the brain to the rest of your body. The spinal cord, made of a bundle of nerves running up and down the spine, is similar to a superhighway, speeding messages to and from the brain at every second.

Central Nervous System vs Peripheral Nervous System

Sources: Brain, Brain, Autonomic Sites, Nerves

Central Nervous System

This consists of 2 structures: the brain and spinal cord. Different sections of the brain regulate and control various regions of our bodies.  The main ones are:

  • Cerebrum (or brain) is divided into two regions, or “hemispheres”, that are connected by an information highway, the corpus callosum.  Often the right hemisphere is associated with creativity, whereas the left is associated with logic.
  • Cerebellum (or “little brain”) regulates the coordination of movement and balance.
  • Brain stem controls vital, life support, involuntary activities (breathing and heart rate).

– Each half of the Cerebrum is further divided into four different lobes:

  • Frontal lobe is the higher, control centre where consciousness lies and is involved in problem solving.
  • Parietal lobe perceives stimuli such as taste and somatosensory (touch) as well as aiding speech and reading.
  • Occipital lobe is devoted to the most information intensive sense of all, vision.
  • Temporal lobe controls hearing and speech, as well as being involved in the integration of 2 or more senses into a meaningful concept (Gestalt).

Peripheral Nervous System

This consists of sensory and motor nerves, whereby the sensory carry information to the CNS, whilst the motor carry information away from the CNS. It can be divided into the Autonomic Nervous System (ANS) and the Somatic System.  The former regulates involuntary, subconscious activities such smooth muscle tone, the heart rate and digestion, whilst the latter controls voluntary, skeletal, muscle movement. The Autonomic Nervous System can be further divided into the Sympathetic and the Parasympathetic systems.  These work in a complimentary manner and are 2 halves of control processes that maintain optimal, body conditions (homeostasis).

  • Sympathetic response prepares us for “fight or flight”, which is most commonly known for its increased heart rate, dilated bronchial muscles, increased blood pressure, and digestive slowdown.
  • Parasympathetic response is described as “rest and digest”, which  promotes energy conservation such as a slower heart rate, decreased blood pressure, and bronchial muscle and urinary bladder constriction.

 

Further Reading

Dustin Curtis is a neuroscientist turned graphic designer and his web site combines the best of both these worlds: interesting concepts of the brain and stunning visuals, Check it out.

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5 Responses to The Nervous System

  1. I’m writing a workbook on healing trauma. I would like permission to use the graphic you have on your site “http://climatereview.net/ChewTheFat/?p=1015” on “The Nervous System”. Do you, or someone else you’re aware of, have rights to this graphic that I might be able to get permission to use. Thanks, Richard Miller

  2. Jimbo says:

    Greetings Richard,

    How are things?

    I was looking for a graphic to sum up the CNS and PNS in one holistic place. At the time, I couldn’t find one that suited, so I created the one in this post. I used individual parts from others to help me create this summary:

    http://bthsbioteacher.wikispaces.com/Nervous+System+Vocab
    http://www.nature.com/nrn/journal/v6/n10/images/nrn1765-f1.jpg
    http://pharmacology-online.blogspot.com/2011/04/neurotransmitter-chemistry-of-autonomic.html

    I can’t speak for my sources, but my graphic is open source and I’m happy for you to use it as you see fit.

    Cheers,
    James

  3. George Ellis says:

    I would also like permission to reproduce this great graphic (http://climatereview.net/ChewTheFat/?p=1015) in a book, with acknowledgement. Can I take it from the above response to Jimbo that this is OK? if so what acknowledgement do you want? Many thanks, George Ellis

    • Jimbo says:

      Greetings George,

      Please feel free to reproduce this graphic in your book. A short, standard acknowledgement would be appreciated.

      Many thanks, James

  4. George Ellis says:

    Sorry I meant response to Richard.

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