Essentials of Human Anatomy

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Essentials of Human Anatomy Physiology
The Nervous System Chapter 7
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Nervous System Functions

• 1. Sensory input gathered information
• Allows you to monitor changes occurring in
  outside of the body (changes stimuli)
• 2. Integration
• Process and interpret the sensory input and
  decide if action is needed
• 3. Motor output
• A response to integrated stimuli activates
  muscles or glands

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Structural Classification of the Nervous System

• Central Nervous System (CNS)
• Brain
• Spinal cord
• Peripheral Nervous System (PNS)
• Nerves that extend from the brain and spinal cord

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Functional Classification of the Peripheral
Nervous System

• Sensory (afferent) division
• Nerve fibers that carry information to the
  central nervous system

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Functional Classification of the Peripheral
Nervous System

• Motor (efferent) division
• Nerve fibers that carry impulses away from the
  central nervous system

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Functional Classification of the Peripheral
Nervous System

• Motor (efferent) division
• Two subdivisions
• Somatic nervous system Voluntary
• Autonomic nervous system Involuntary
• Sympathetic
• Parasympathetic

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Organization of the Nervous System
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Nervous Tissue Support Cells

• Supporting Cells in the CNS
• Lumped together as neuroglia (AKA- glia or glial
  cells)
• Nerve glue
• Includes many types of cells that support,
  insulate, protect the delicate neurons
• Each type has specific functions

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Nervous Tissue Neurons

• Neurons Nerve cells
• Cells specialized to transmit messages
• Nerve impulses
• Major regions of Neurons
• Cell body Contains the nucleus and is the
  metabolic center of the cell
• Processes Fibers that extend from the cell body
  (dendrites and axons)

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Neuron Anatomy

• Cell body
• Nucleus
• Metabolic Center

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Neuron Anatomy

• Extensions outside the cell body
• Dendrites Conduct impulses toward the cell body
• Axons Conduct impulses Away from the cell body

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Axons and Nerve Impulses

• Axons end in axonal terminals
• Axon terminals contain vesicles that contain
  neurotransmitters
• Axon terminals are separated from the next neuron
  by a gap
• Synaptic cleft just the space between adjacent
  neurons
• Synapse junction between neurons including the
  membranes of both neurons the space between them

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Nerve Fiber Coverings

• Myelin
• Covers nerve fibers
• Whitish, fatty material
• Waxy appearance
• Protects insulates the fibers
• Increases the transmission rate of nerve impulses
• Schwann cells produce myelin sheaths in
  jelly-roll like fashion
• Nodes of Ranvier gaps in the myelin sheath
  along the axon

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Application of Neurons

• Multiple sclerosis (MS)
• Chronic, potentially debilitating disease that
  affects the central nervous system, which is made
  up of the brain and spinal cord.
• Myelin sheath is destroyed- It hardens to a
  tissue called the scleroses
• Transmitted nerve impulses are short-circuited
• Affected person loses control of his/her muscles
  and becomes increasingly more disabled
• Autoimmune disease
• Protein component of the sheath is attacked
• No cure
• Interferon injections
• Hormone like substance released by some immune
  cells- provides relief
• website

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Multiple Sclerosis
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Neuron Cell Body Location

• Most neurons are found in the central nervous
  system
• White matter- dense collections of myelinated
  fibers
• Gray matter unmyelinated fibers cell bodies
• Nuclei clusters of cell bodies within the white
  matter of the central nervous system
• Ganglia collections of cell bodies outside the
  central nervous system (PNS)

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Functional Classification of Neurons

• Sensory (afferent) neurons
• Carry impulses from the sensory receptors to the
  CNS
• Cutaneous sense organs (Vision, hearing,
  equilibrium, taste smell)
• Proprioceptors detect stretch or tension in
  skeletal muscles, tendons and joints
• Pain receptors

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Functional Classification of Neurons

• Motor (efferent) neurons
• Carry impulses from the central nervous system to
  the viscera and/or muscles and glands
• Interneurons (association neurons)
• Connect sensory and motor neurons in neural
  pathways

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Neuron Classification