Chapter 7: The Nervous System

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Chapter 7 The Nervous System
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I. Functions of the Nervous System

• A. Sensory Input- gathering information to
  monitor changes occurring inside and outside the
  body
• B. Integration- to process and interpret sensory
  input and decide if action is needed
• C. Motor Output- A response to integrated
  stimuli, the response activates muscles or glands

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II. Organization of the Nervous System

• A. Structural Classification- Two Subdivisions
• 1. Central Nervous System (CNS) - occupies
  the dorsal cavity,
• integration and commanding
• centers
• a. includes the brain and
• spinal cord
• 2. Peripheral Nervous System
• (PNS) - contains mainly the
• nerves that extend from the
• brain and spinal cord
• a. includes cranial and spinal
• nerves

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B. Functional Classification- concerned only with
the PNS and has two subdivisions

• 1. Sensory or Afferent division- Nerve fibers
  that carry information to the central nervous
  system
• 2. Motor or Efferent division- Nerve fibers that
  carry impulses away from the central nervous
  system. The Two subdivisions are the somatic and
  autonomic nervous system.
• a. Somatic nervous system voluntary
• b. Autonomic nervous system involuntary
  further divided into the sympathetic and
  parasympathetic divisions.
• i. Sympathetic division- the fight-
• or-flight system. Its activity is
• evident when we are frightened, in
  emergency, or threatening situations.
• ii. Parasympathetic division-
• sometimes called the resting and
  digesting system. It is
• most active when the body is at rest
  and not threatened.

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Organization of the Nervous System
Sensory neurons
Motor neurons
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B. Neurons- excitable little cells that make
use of their potential!

• 1. Cells specialized to transmit messages
• 2. Major regions of neurons
• a. Cell body- nucleus and metabolic center
• b. Processes- fibers that extend from the body
• 1) dendrites- convey messages towards the cell
  body
• 2) axons- conduct messages away from the cell
  body, axons usually end with terminals that
  contain vesicles (small sacs) that
  contain neurotransmitters
• c. Synapse- the space between two neurons

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• 3. Nerve Fiber Coverings
• a. Schwann Cells- produce myelin sheaths-
  wrapped membranes that enclose the axon
• b. Nodes of Ranvier- gaps in myelin sheaths
  along the axon- allows the impulse to travel
  quickly down the neuron