Nervous System

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Nervous System
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Basics

• Intricate communication network
• Regulates functions and behaviour of the body
• Composed of the brain, spinal cord, and nerves

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Characteristics of the NS

• Helps to maintain homeostasis
• Receives and processes information throughout the
  body
• Integrates mass amounts of information very
  quickly
• (over 300km / hour)

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How it works

• Receives information from a stimulus
• Responds with the body
• Examples???
• Stimulus Reception Response

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Stimuli

• We usually think of stimulus coming from the
  exterior
• Can also come from inside the body (medications
  in the bloodstream)

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Other Systems

• The nervous system must work with other systems
  in order to function
• the sensory system
• the motor system

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Example

• Eye would be part of the sensory system
• Receives the information from a stimulus
• Legs are part of the motor system which responds
  to the stimulus

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The Nervous SystemFlow Chart
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Anatomy of the NS
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2 Kinds of Cells

• Neurons
• active cells in the nervous system
• conduct nerve impulses (electrical signals)
• Glial Cells
• do not conduct nerve impulses
• glue cells provide support
• holds neurons together (telephone wire)

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Nerve Anatomy
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Nerve Anatomy

• Neurilemma
• Thin membrane that surrounds the axon
• Promotes regeneration of damaged axons
• Why feeling gradually returns to fingers
  following a paper cut
• Severed neurons are rejoined

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Nerve Anatomy

• Dendrites Receive information, conduct nerve
  impulses toward cell body.
• Axon Carries information toward other neurons
  or effectors, away from the cell body (more than
  100 in a human hair)
• Myelin Sheath Layer of white fatty protein,
  formed by the Scwann cells and insulates the axon
  by preventing loss of charged ions
• Nodes of Ranvier areas between sections of
  myelin sheath

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Myelin Sheath

• Variety of diseases / disorders involving the
  myelin sheath
• Multiple Sclerosis (MS)
• Covering is lost in some places, lesions
• Interferes with conduction of electrical signals
  to and from brain
• Problems walking, vision, fatigue, numbness,
  possibly cognitive dysfunction

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White and Gray Matter

• White Matter
• Nerves in the brain that contain both a myelin
  sheath and neurilemma
• Gray Matter
• Nerves in the brain and spinal cord that lack a
  myelin sheath
• Any damage is perminant

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Ganglia

• Neurons are not found randomly throughout the
  body
• Ganglia Locations at which the cell bodies of
  several neurons are clustered together
• Exist in the peripheral nervous system

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Kinds of Neurons

• Sensory Neurons
• Relay information from the environment to the
  central nervous system for processing
• Senses

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Kinds of Neurons

• Motor Neurons
• Relay information to the effectors (muscles and
  glands)
• Ex. Tells your muscles to move (fingers)

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Kinds of Neurons

• Interneurons
• Link neurons within the body
• Found mostly in the brain and spinal cord
• Integrate and interpret the sensory information
  and connect to motor neurons