Anatomy

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Author:
alannaheeres
ID:
108822
Filename:
Anatomy
Updated:
2011-10-13 21:43:57
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Nervous System
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Nervous System 1
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  1. Controls and integrates all body activities (along with the endocrine system)
    Nervous Tissue
  2. What are the three basic function?
    • 1. Sensory
    • 2. Integration
    • 3. Motor
  3. Sensing changes with sensory receptors
    Sensory function
  4. Interpreting and remembering those changes
    Integration function
  5. Reacting to those changes with effectors
    -Muscular contractions
    -Glandular secretions
    Motor function
  6. Nervous System Division:
    Consists of the brain and spinal cord
    Central nervous system (CNS)
  7. Consists of cranial and spinal nerves that contain both sensory and motor fibers
    Connects CNS to muscles, glands & all sensory receptors
    Peripheral nervous system (PNS)
  8. Subdivisions of the PNS
    Sensory neurons from sensory receptors to the CNS
    Motor neurons to skeletal muscle tissue
    Somatic (voluntary) nervous system (SNS)
  9. Sensory neurons from visceral organs to CNS
    Motor neurons to smooth & cardiac muscle and glands
    Autonomic (involuntary) nervous systems
  10. Autonomic nervous system:
    Fight or flight
    Sympathetic division
  11. Autonomic nervous system:
    Rest & digest
    Parasympathetic division
  12. Histology of Nervous Tissue
    Consists of two main cell types:
    • Neurons
    • Neuroglia (nerve glue)
  13. Half of the volume of the CNS
    Smaller cells than neurons
    50X more numerous
    Neuroglial Cells
  14. Cells can divide – rapid mitosis in tumor formation (gliomas)
    Neuroglial cells
  15. What are the 4 cell types in CNS?
    • 1. Astrocytes
    • 2. Oligodendrocytes
    • 3. Microglia
    • 4. Ependymal
  16. What are the 2 cell types in PNS?
    • 1. Schwann
    • 2. Satellite cells
  17. Star-shaped cells
    Form blood-brain barrier by covering blood capillaries
    Astrocytes
  18. Metabolize neurotransmitters
    Regulate K+ balance
    Provide structural suppor
    Astrocytes
  19. Most common glial cell type
    Each forms myelin sheath around more than one axon in CNS
    Oligodendrocytes
  20. Analogous to Schwann cells of PNS
    Oligodendrocytes
  21. Small cells found near blood vessels
    Phagocytic role -- clear away dead cells
    Microglia
  22. Derived from cells that also gave rise to macrophages & monocytes
    Microglia
  23. Form epithelial membrane lining cerebral cavities & central canal
    Produce cerebrospinal fluid (CSF)
    Ependymal cells
  24. Flat cells surrounding neuronal cell bodies in peripheral ganglia
    Satellite Cells
  25. Support neurons in the PNS ganglia
    Satellite Cells
  26. Cells encircling PNS axons
    Schwann Cells
  27. Each cell produces part of the myelin sheath surrounding an axon in the PNS
    Schwann Cells
  28. Functional unit of nervous system
    Neurons
  29. Neurons: Have capacity to produce action potentials
    Electrical excitability
  30. Single nucleus with prominent nucleolus
    Nissl bodies (chromatophilic substance)
    -- rough ER & free ribosomes for protein synthesis
    Neurofilaments give cell shape and support
    Microtubules move material inside cell
    Neuron Cell Body
  31. Neuron Cell Processes
    Dendrites & Axons
  32. Dendrites: Conducts impulses _________ the cell body (receptive zone)
    towards
  33. Typically short, highly branched & unmyelinated
    Surfaces specialized for contact with other neurons
    Contains neurofibrils & Nissl bodies
    Dendrites
  34. Axon: Conduct impulses ________ from cell body (conductive zone)
    away
  35. Long, thin cylindrical process of cell
    Arises at axon hillock
    Impulses arise from initial segment (trigger zone)
    Axons
  36. Side branches (collaterals) end in fine processe
    Axon terminals
  37. Swollen tips that contain vesicles filled with neurotransmitters
    Synaptic end bulbs
  38. What are axons surrounded by?
    A lipid and protein covering (myelin sheath)
  39. What is the myelin sheath produced by?
    Schwann cells
  40. Myelinated axons appear what color?
    White
  41. Axon Coverings in PNS:
    jelly-roll like wrappings made of lipoprotein
    Myelin
  42. Acts as electrical insulator
    Speeds conduction of nerve impulses
    Myelinated axons
  43. Axon Coverings in PNS:
    Regular spaces or gaps in myelin sheath
    nodes of Ranvier
  44. Axon Coverings in PNS:
    Slow, small diameter fibers
    Surrounded by glia cell processes but no myelin sheath wrapping
    Unmyelinated fibers
  45. Myelination in PNS:
    What myelinate (wrap around) axons in the PNS during fetal development?
    Schwann cells
  46. Forms outermost part with inner portion being the myelin sheath
    Schwann cell cytoplasm & nucleus
  47. Guides growing axons that are repairing themselves
    Tube
  48. Parts of a synapse:
    Synaptic end bulb
    Synaptic vesicles
    Presynaptic membrane
    Presynaptic end bulb
  49. What are the three parts of a synapse?
    • 1. Presynaptic neuron
    • 2. Synaptic cleft
    • 3. Postsynaptic neuron
  50. Parts of a synapse:
    Postsynaptic membrane
    Neurotransmitter receptor sites
    Postsynaptic neuron
  51. Transmission of Nerve Impulse:
    Axon terminals form synapses on dendrites and cell body
    • Neuronal excitation and inhibition
    • (excitatory and inhibitory neurotransmitters)
  52. Summation takes place at initial segment on axon hillock (concentration of Na ion channels)
    Nerve impulse generation
  53. At threshold Na channels open and nerve impulse is conducted down the axon
    Myelinated axon, Na channels open at nodes of Ranvier, saltatoryconduction
    Unmyelinated axon, Na channels open on adjacent patch of membrane, slower
    Nerve impulse conduction along axon
  54. Structural Classification of Neurons is based on:
    Number of processes found on cell body
  55. Several dendrites & one axon
    Most common cell type
    Multipolar
  56. One main dendrite & one axon
    Found in retina, inner ear & olfactory
    Bipolar neurons
  57. One process only (develops from a bipolar)
    Are always sensory neurons
    Unipolar neurons
  58. What are the three functional classifications of neurons?
    • 1. Sensory (afferent) neurons
    • 2. Motor (efferent) neurons
    • 3. Interneurons (association) neurons
  59. Transport sensory information from skin, muscles, joints, sense organs & viscera to CNS
    Sensory (afferent) neurons
  60. Send motor nerve impulses to muscles & glands
    Motor (efferent) neurons
  61. Connect neurons to neurons
    90% of neurons in the body
    Interneurons (association) neurons
  62. single cell stimulates many other
    Diverging
  63. One cell stimulated by many others
    Converging
  64. Impulses from later cells repeatedly stimulate early cells in the circuit (short-term memory)
    Reverberating
  65. Single cell stimulates a group of cells that all stimulate a common postsynaptic cell (math problems)
    Parallel-after-discharge
  66. Sprouting of new dendrites
    Synthesis of new proteins
    Changes in synaptic contacts with other neurons
    Plasticity maintained throughout life
  67. PNS can repair damaged dendrites or axons
    CNS no repairs are possible
    Limited ability for regeneration (repair)
  68. Axons and dendrites may be repaired if... (3 reasons)
    • 1. Neuron cell body remains intact
    • 2. Schwann cells remain active and form a tube
    • 3. Scar tissue does not form too rapidly
  69. 24-48 hours after injury, Nissl bodies break up into fine granular masses
    Chromatolysis
  70. Repair within the PNS:
    How long...
    Wallerian degeneration occurs (breakdown of axon & myelin sheath distal to injury)
    Retrograde degeneration occurs back one node
    By 3-5 days
  71. How long for regeneration when:
    Neuroglia on each side of injury repairs tube (Schwann cell mitosis)
    Axonal buds grow down the tube to reconnect (1.5 mm per day)
    Within several months

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