Nervous System

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Nervous System Sense Organs
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• Nervous system - brain, spinal cord, nerves,
  sense organs, receptors
• Controls coordinates body movements and senses
  controls consciousness helps monitor other
  systems

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• Two major divisions central nervous system
  peripheral nervous system
• Central brain and spinal cord
• Peripheral neurons not part of brain spinal
  cord

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• Central Nervous System (CNS) spinal cord
  carries messages to/from brain where they are
  interpreted and analyzed
• Brain oversees daily operations of body and
  interpreting information

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• Cerebrum largest portion of the brain site of
  higher brain functions
• Cerebral Hemispheres right and left divisions
  of the cerebrum site of control centers for
  various functions

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• Corpus callosum-lies within the central groove of
  the cerebrum connecting the right left
  hemispheres.

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• Cerebral cortex outer layer of cerebrum
  important in processing senses and motor
  responses
• Control centers for various functions are found
  in different areas of brain (pg 1005 fig. 50-3)

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• Brain Stem connects cerebrum to spinal cord
• Upper Brain Stem -(thalamus hypothalamus)
  contains important relay centers of info.
  entering and exiting the brain

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• Thalamus directs incoming signals to proper
  area of brain
• Hypothalamus controls much of the bodys
  hormone production

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• Lower Brain Stem 3 divisions (midbrain, pons,
  medulla oblongata)
• Midbrain relay center for auditory/visual info.
• Pons connects cerebrum and cerebellum

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• Medulla Oblongata controls heart respiration
  rate relay center
• Cerebellum coordinates muscle action

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Figure 35-9 The Brain
Section 35-3
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• Spinal Cord column of nerve tissue runs from
  medulla oblongata through vertebral column
• 31 pairs of spinal nerves part from spinal cord
  and branch out to rest of body

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• Peripheral Nervous System
• Neurons not included in brain and spinal cord
• Afferent neurons carry info. to spinal cord
• Efferent neurons carry info. From spinal cord

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• Sensory Division
• Part of PNS that aquires info. from internal and
  external environment (ex. Pressure, heat, etc.)

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• Motor Division
• Part of PNS that allows the body to react to
  sensory information (movement of muscles, etc.)

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• Somatic Nervous System motor division
  controlling movement of skeletal muscles

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• Autonomic Nervous System motor division
  controlling movement of smooth muscles
  involuntary controls internal conditions

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• Sympathetic division- fight or flight response.
  Activated by physical emotional stress.
• Parasympathetic division-signals the body to
  revert back to normal activity after fight or
  flight response.

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• Neurons specialized cells that transmit
  information throughout the body
• Axon threadlike projection from the cell body
  of neuron moves nerve impulses away from the
  cell body

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• Dendrites smaller projections connecting
  neurons carry nerve impulses toward neurons
• Myelin sheath-axon insulator speeds up the
  nerve impulse

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• Axon terminal-stores neurotransmitters that are
  used to send chemical messages to other neurons.

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• Sensory Receptors
• Receptors designed to detect a stimulus
• Mechanoreceptors respond to movement pressure
  and tension

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• Photoreceptors respond to variations in light
• Chemoreceptors respond to chemicals
• Thermoreceptors respond to changes in temp.
• Pain receptors respond to tissue damage