ANAPHY

• Organization of Nervous System

  
• Functions of the Nervous System

  • For sensory input—gathering information
  • For integration—to process and interpret sensory input and decide if action is needed
  • For motor output—to effect a response by activating muscles or glands (effectors) via motor output

  
• Structural Classification of the Nervous System

  • Central nervous system (CNS)
  • Peripheral nervous system (PNS)

  
• Central nervous system (CNS)


  Organs: Brain, Spinal cord

  Function: Integration; command center, Interpret incoming sensory information, Issues outgoing instructions

  
• Peripheral nervous system (PNS)


  Nerves extending from the brain and spinal cord, part of your nervous system that lies outside your brain and spinal cord

  Spinal nerves: carry impulses to and from the spinal cord, mixed nerves that interact directly with the spinal cord to modulate motor and sensory information from the body's periphery

  Cranial nerves: carry impulses to and from the brain, send electrical signals between your brain, face, neck and torso

  Functions: Serve as communication lines among sensory organs, the brain and spinal cord, and glands or muscles

  
• Functional Classification of the Peripheral Nervous System

  • Sensory (afferent) division
  • Motor (efferent) division

  
• Parasympathetic Nervous System


  A network of nerves that relaxes your body after periods of stress or danger, helps run life-sustaining processes, like digestion, during times when you feel safe and relaxed
• Sympathetic Nervous System


  A network of nerves that helps your body activate its "fight-or-flight" response, increases activity when you're stressed, in danger or physically active
• Nervous tissue has support cells grouped together as "neuroglia" 'nerve glue' 'glial cells'

  
• Types of Support Cells- Neuroglia

  • Astrocytes
  • Microglia
  • Ependymal cells
  • Oligodendrocytes
• Astrocytes


  Abundant, star-shaped cells that brace neurons, form barrier between capillaries and neurons, control the chemical environment of the brain
• Microglia


  Spiderlike phagocytes that dispose of debris
• Ependymal cells


  Line cavities of the brain and spinal cord, cilia assist with circulation of cerebrospinal fluid
• Oligodendrocytes


  Wrap around nerve fibers in the central nervous system, produce myelin sheaths

  
• Glial cells or Neuroglia are support cells that do not transmit nerve impulses and never lose their ability to divide

  
• 2 Major Varieties of Support Cells

  • Satellite cells
  • Schwann cells
• Satellite cells


  Protect neuron cell bodies
• Schwann cells


  Form myelin sheath in the peripheral nervous system

  
• Major Regions of Neurons

  • Cell body
  • Processes

  
• Cell body


  Nucleus and metabolic center of the cell, contains Nissl bodies, neurofibrils, and a large nucleolus
• Dendrites


  Conduct impulses toward the cell body
• Axons


  Conduct impulses away from the cell body, end in axon terminals containing neurotransmitter vesicles, separated from next neuron by a synapse

  
• Myelin sheath


  Whitish, fatty material covering axons, produced by Schwann cells in the PNS and oligodendrocytes in the CNS, with gaps called nodes of Ranvier

  
• Most neuron cell bodies are found in the central nervous system

  
• Terminologies


  • Gray matter
  • Nuclei
  • Ganglia
  • Tracts
  • Nerves
  • White matter
• Functional Classification of Neurons

  • Sensory (afferent) neurons
  • Motor (efferent) neurons
  • Interneurons (association neurons)

  
• Sensory (afferent) neurons


  Carry impulses from the sensory receptors to the CNS, include cutaneous receptors in the skin and proprioceptors in muscles, joints, and tendons

  
• Motor (efferent) neurons


  Carry impulses from the central nervous system to viscera, muscles, or glands

  
• Interneurons (association neurons)


  Found in neural pathways in the central nervous system, connect sensory and motor neurons

  
• Structural Classification of Neurons

  • Multipolar neurons
  • Bipolar neurons
  • Unipolar neurons

  
• Multipolar neurons


  Many extensions from the cell body, all motor and interneurons are multipolar, most common structure

  
• Bipolar neurons


  One axon and one dendrite, located in special sense organs such as nose and eye, rare in adults
• Unipolar neurons


  Have a short single process leaving the cell body, sensory neurons found in PNS ganglia
• Functional Properties of Neurons

  • Irritability
  • Conductivity

  
• Irritability


  Ability to respond to stimuli
• Conductivity


  Ability to transmit an impulse
• Multipolar neurons


  • Many extensions from the cell body
  • All motor and interneurons are multipolar
  • Most common structure

  
• Bipolar neurons


  • One axon and one dendrite
  • Located in special sense organs such as nose and eye
  • Rare in adults
• Unipolar neurons


  • Have a short single process leaving the cell body
  • Sensory neurons found in PNS ganglia
• Saltatory conduction


  Faster impulse transmission in myelinated neurons