Nervous System

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Nervous System

• Cali Hazel, Mary Kuttler.

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Evolution of the Nervous System

1. Protists do not have a nervous system due to the
   simplicity of their structure. They are capable
   of response to their environment but not in this
   way.
2. This is the start of cephalization (development
   of the brain). Cnidarians have the simplest
   nervous system of the Animal Kingdom, they have a
   network of nerves that conducts signals from
   sensory cells to muscle cells. But their nervous
   system is not centralized.
3. Many flatworms have a netlike nerve system like
   cnidarians but some have a more organized and
   complex system with a  brain and spinal chord.
   The nervous system of Planarians is in the form
   of a ladder.
4. The nervous systems of mollusks are very diverse.
   Some have bivalves and no cephalization while
   others have slight cephalization. The most
   advanced group of mollusks  have complex sense
   organs and are highly cephalized.

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• Annelids and Arthropods have repeating segments
  and an anterior brain. Each individual segment
  has a ganglion, which is a nerve chord.
• Sea stars have a central nerve ring and a nerve
  that extends from the ring into each arm. Each
  arm also contains a nerve net.
• The nervous system of vetrebrates is the most
  cephalized and contains complex sense organs to
  inhibit very complex activities.

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Nervous Systems in Humans

• The human nervous system is broken into two main
  parts.
• The central nervous system
• The peripheral nervous system
• Both systems are broken into two parts
• In the central nervous system collections of
  neurons are called nuclei and collections of
  axons are call tracts.
• In the peripheral nervous system collections of
  neurons are called ganglia and collections of
  axons are called nerves.

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Central Nervous System

• Brain
• Weigh approximately 3 lbs.
• Contains 100 billion nuerons (nerve cells).
• Contains trillions of glia (support cells).
• The two hemispheres communicate through a bundle
  of nerve fibers called the corpus callosum

• Spinal Chord
• Is around 43cm long in adult women.
• Is around 45 cm long in adult men.
• Weighs around 35-40g.
• The vertebral column is the back bone (collection
  of bones) that houses the spinal cord and is
  about 70 cm long.

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The Brain

• Cerebral Cortex - Thought, Voluntary movement,
  Language, Reasoning, Perception
• Cerebellum - Movement, Balance, Posture
• Brain stem - Breathing, Heart Rate, Blood
  Pressure
• Hypothalamus - Body Temperature, Emotions,
  Hunger, thirst, Circadian Rhythms
• Thalamus - Sensory processing, Movement
• Limbic System - Emotions, Memory
• Hippocampus - Learning, Memory
• Basal Ganglia - Movement
• Midbrain - Vision, Audition, Eye Movement, Body
  Movement

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Periphial Nervous System

• Somatic Nervous System
• Contains peripheral nerve fibers.
• The fibers send sensory information to the
  central nervous system.
• Also they send sensory information to motor nerve
  fibers that project to skeletal muscle.

• Autonomic Nervous System
• Three Parts, the sympathetic nervous system, the
  parasympathetic nervous system and the enteric
  nervous system.
• Controls smooth muscle of the internal organs
  (viscera) and glands.

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• The Sensory (afferent) neurons carry information
  into the central nervous system from sense organs
  
• the motor (efferent) neurons  carry information
  away from the central nervous system (for muscle
  control).
• the Cranial neurons  connect the brain with the
  periphery
• the spinal neurons  connect the spinal cord with
  the periphery.
• Somatic neurons connect the skin or muscle with
  the central nervous system 
• the visceral neurons connect the internal organs
  with the central nervous system.

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Bibliography

• "Blindness Causes Structural Brain Changes,
  Implying Brain Can Re-organize Itself to Adapt."
  Science Daily News Articles in Science,
  Health, Environment Technology. 2010. Web. 05
  Apr. 2011.
• Chudler, Erik H. "Neuroscience For Kids - Explore
  the Nervous System." UW Faculty Web Server. 2010.
  Web. 05 Apr. 2011.
• Gregory PhD, Michael J. "The Nervous System
  Organization." Clinton Community College. 2006.
  Web. 05 Apr. 2011.
• Evers, Christine A., Lisa Starr, Cecie Starr, and
  Ralph Taggart. "34." Biology The Unity and
  Diversity of Life. 11th ed. Belmont, CA Thomson
  Brooks/Cole, 2006. 574-95. Print.