The Central Nervous System

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					                The Central Nervous System
                         The Brain and Spinal Cord

The Spinal Cord

        Main pathway for information connecting brain and PNS
        Exits the skull through an opening called the foramen magnum
        Protected by the bony vertebral column (the spine)
        Two nerve tissue types: white matter and grey matter
        Grey matter = unmyelinated axons of motor neurons
        White matter = unmyelinated axons of interneurons
        Dorsal (“back”) nerve tract relays sensory information into the spinal
        Ventral (“front”) nerve tract relays motor information from the
        spinal cord to the effectors (muscles and glands)

The Brain

The human brain has 3 main regions, the forebrain, midbrain and hindbrain.
It contains approximately 100 billion neurons, making it the most complex
organ in the human body.

The cerebrum makes up a large part of the forebrain, and is responsible for
determining intelligence and personality, interpreting sensory impulses, and
motor functioning. The cerebrum is divided into two hemispheres (the left
and the right), which are connected by a thick band of fibers called the
corpus callosum. The folded surface of the cerebrum is known as the
cerebral cortex.

The cerebellum is the largest section of the hindbrain and functions to
coordinate movements of muscles and joints, as well as to control balance.
The pons (a bundle of fibers that acts as a bridge) connects the cerebellum
to the medulla. The medulla, or medulla oblongata, acts as the connection
between the central and peripheral nervous systems, as nerve tracts from
the spinal cord and higher brain centers run through it.
                        Video: The Brain

While watching the video, “The New Living Body: The Brain”, please answer
as many of the following questions as possible.

   1. What is the name for the wrinkly surface of the brain, which contains
      2/3 of the brain’s nerve cells? Answer: The Cortex.

   2. Explain what a Magnetic Resonance Imager (MRI) does. Answer: It
      allows you to look at sections or slices of the brain.

   3. Which brain hemisphere controls movement on the left side of the
      body? Answer: The right hemisphere.

   4. Describe the function of the cerebellum. Answer: Involved in
      controlling limb movement, balance and muscle tone.

   5. What is the name for the area of the brain responsible for sight?
      Answer: The Visual Cortex.

   6. How does a young child’s brain develop? Answer: Neural connections
      are formed in response to stimuli.

   7. What does the brain use for energy? Answer: Glucose.

   8. Which neurotransmitter is missing in the brain of people who suffer
      from Parkinson’s Disease? Answer: Dopamine.

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