neuro exam 1 material

Card Set Information

neuro exam 1 material
2013-02-18 21:22:34
neuro anatomy notes

notes from slides
Show Answers:

  1. The central nervous system consists of...
    The brain and spinal cord
  2. The peripheral nervous system consists of...
    cranial nerves and spinal nerves
  3. What are the major subdivisions of the brain?
    Cerebrum, Diencephalon, Brainstem, Cerebellum
  4. What makes up the brainstem (rostral to caudal)?
    Midbrain, pons, medulla
  5. What lobes are separated by the sylvian (lateral) fissure?
    The frontal and parietal lobes are separated from the temporal lobe by the lateral fissure
  6. The parietal and frontal lobes are separated from the temporal lobe by what structure?
    Sylvian (lateral) fissure
  7. The parieto-occipital sulcus separates what lobes of the brain?
    Separates the occipital lobe from the parietal and temporal lobes
  8. The cingulate gryus surrounds what structure?
    The corpus callosum
  9. What gyrus encompasses the corpus callosum?
    The cingulate gyrus
  10. Name the 4 lobes of the brain
    Frontal, parietal, occipital, temporal
  11. Define neural circuits
    Groups of interconnected neurons that process a specific type of information
  12. A myotactic reflex is an example of...
    A neural circuit
  13. Describe interneurons
    Also known a local circuits, characterized by short axons and project only locally
  14. Define neural systems
    collections of neuronal circuits that interact to serve a broader function, by conveying a particular type of information or accomplishing a specific task
  15. Name three types of neural systems
    • Sensory systems (visual, auditory, etc)
    • Motor systems
    • Association systems
  16. What are neural pathways? What are they comprised of?
    Neural pathways are neuroanatomic substrates of neural systems

    • Comprised of...
    • - nuclei (neuronal cell body clusters in CNS)
    • - regions of cortex (layered sheets of neuronal cell bodies within CNS)
    • - fiber tracts (bundles of axons in CNS)
    • - peripheral nerves
  17. Describe the distribution of gray and white matter in the brain
    Gray matter is located externally (on the periphery of the cortex) and internally (in the diencephalon).  White matter is located internally (in between the areas of gray matter).
  18. What are gray matter and white matter composed of?
    • Gray matter = neuronal cell bodies
    • White matter = fiber tracts

  19. ID structure and function
    Internal capsule

    White matter tract containing axons entering and leaving the cerebral cortex

  20. ID and function

    A collection of nuclei which relay information to and from the cerebral cortex

  21. ID structure, location, and function
    Superior colliculus

    • The roof of the tectum
    • (location:  rostral midbrain)

  22. ID structure, location, and function
    Crus cerebri

    • White matter tract containing axons leaving the cerebral cortex
    • (location: rostral midbrain)

  23. ID structure, location, and function
    • Substantia nigra
    • Part of basal ganglia circuitry - involved in control of movement
    • (location: rostral midbrain)

  24. ID structure, location, and function
    • Contains various nuclei and major ascending (sensory) pathways
    • (location:  mid-pons)

  25. ID structure, location, and function.

    • Contains pontine nuclei and major descending (motor) pathways. Forms "bulge" in pons.
    • (location:  mid-pons)

  26. ID structure, location, and function.
    Inferior Olive

    • Neurons provide one of the major inputs to the cerebellum (extends most of the length of the medulla)
    • (location:  middle medulla)

  27. Identify structure, describe function, and identify location
    • Pyramid
    • Contains major descending pathway (corticospinal axons)
    • (location:  middle and caudal medulla)
  28. Distribution of white and gray matter in spinal cord? Cervical vs lumbar?
    The bulk of the white matter is located externally, while the bulk of the gray matter is located internally.

    White matter decreases from superior to inferior.  Gray matter increases superior to inferior.

  29. ID and Function
    A.  Posterior funiculus - contains ascending tracts, bordered by midline medially and dorsal horn laterally

    B.  Lateral funiculus - contains mainly descending tracts, bordered by dorsal horn superiorly (and medially), ventral horn inferiorly, and posterior funiculus inferiorly

    C.  Anterior funiculus - contain mainly descending tracts, bordered by ventral horn and lateral funiculus superiorly

  30. ID and function
    A.  Ventral horn - contains motor neurons and interneurons

    B.  Dorsal horn - contains sensory neurons and interneurons
  31. List the 5 steps in neural circuit construction
    1.  Formation of primitive neural system from neural ectoderm

    2.  Generation of neurons and glia

    3.  Migration of neurons from site of generation to final destination

    4.  Interconnection of neurons by axonal growth

    5.  Formation and maintenance of synaptic connections
  32. Notochord forms from...
  33. Inductive signals from ______ lead to formation of neural plate from ectoderm
  34. Inductive signals from notochord lead to formation of _______ from ectoderm
    neural plate
  35. Formation of _______ by invagination of neural plate
    neural groove
  36. Lips of neural groove become...
    neural crests
  37. Ventral groove becomes...
    (early neuralation)
    floor plate
  38. Lips of neural groove meet and fuse to form...
    neural tube
  39. Anterior neural folds form _____, rest of neural tube becomes ________
    brain, spinal cord
  40. Sensory and autonomic ganglia come from...
    (late neuralation)
    neural crest cells
  41. ______ induce differentiation of adjacent cells into motor neurons
    floor plate cells
  42. Four migratory paths of neural crest cells
    • 1.  Sensory ganglia
    • 2.  Autonomic ganglia
    • 3.  Adrenal secretory cells
    • 4.  non-neuronal cells (e.g. melanocytes)
  43. Three developmental defects
    • Spina bifida
    • Anencephaly - brain doesn't develop
    • Encephalocoele - brain herniation
  44. List the three primary brain vesicles and the two flexures
    • 1. Prosencephalon (forebrain)
    • 2. Mesencephalon (midbrain)
    • 3. Rhombencephalon (hindbrain)

    • 1. Cepahalic flexure (nesencephalon)
    • 2. Cervical flexure (rhombencephalon)
  45. Ventricles form from...
    the lumen of the neural tube
  46. List the five secondary brain vesicles
    • 1.  Telencephalon
    • 2.  Diencephalon
    • 3.  Mesencephalon
    • 4.  Metencephalon
    • 5.  Myelencephalon
  47. Review Adult Brain Derivatives Table
  48. The roof of the fourth ventricle is formed by...
  49. The floor of the fourth ventricle is formed by...
    Pons (rostrally) and medulla (caudally)
  50. From what type of epithelium is the neural tube composed?
    Pseudostratified (columnar)

    • pial surface
    • -----------------------------------
    • neuroepithelial cells
    • -----------------------------------
    • neural tube lumen (ventricle)
  51. In mitosis, cells lose their connection with the _____, surface.  
  52. After proliferation is complete, precursor cells exit the cell cycle and become postmitotic.  Timing of this event is called ________ of the cell
  53. Asymmetrical mitotic division of a precursor cells results in...
    one postmitotic neuroblast and one progenitor cell with limited mitotic potential
  54. Noggin and chordin are antagonist to...
  55. Neural precursors (stem cells) are generated through induction by ________ activity
  56. Gradient of ______ and _______ influence precursor identity and establish local organizers, such as roof plate and ventral plate
    TGF-B (dorsal centers), sonic hedgehog (ventral centers)
  57. 1. ______ promotes differentiation of neuroblasts into neurons

    2. ______ inhibits neurogenesis

    3.  ______, ______, and ______ promote formation of olgiodendrocytes

    4.  ______ and ______ promote differentiation of neuroblasts to astrocytes
    • 1. bHLH genes
    • 2. notch
    • 3. Olig1, olig2, and Nkx2.1
    • 4. notch, neureglin
  58. The two main purposes for migration
    1. Allows for interaction of different classes of neurons by bringing them together at specific times and places.

    2.  Ensure final position of each neuron and integration into appropriate functional circuit
  59. Microglial cells come from what embryonic cell layer?
  60. Two main methods of neuron migration (PNS and CNS)
    1. PNS - neural crest cells guided by secreted molecules, adhesion molecules in extracellular matrix or cell surface molecules

    2. CNS - most cells attach to radial glia (eg cerebral cortex, cerebellum, hippocampus, spinal cord)
  61. Describe migration by neural glial cells
    Neurons attach glia as they extend from ventricular surface to pia
  62. What is an axon growth cone?
    Specialized structure at the tip of a growing axon

    Formed when axon reaches a decision point

    highly motile, exploring extracellular environment

    Determines direction of axon growth
  63. What are the dynamics of axonal growth cones (assembly and disassembly)?
    Assembly - cytoskeletal elements of filopodium response to attractive cues

    Disassembly - cytoskeletal elements response to repulsive cues
  64. Explain the growth cones at the optic chiasm (temporal vs nasal)
    Temporal retinal axons do not cross the midline due to repulsive cues

    Nasal retinal axons do cross the midline due to attractive cues
  65. What are 3 non-diffusible axon growth signals?
    1. Extracellular matrix adhesion molecules

    2. Cell adhersion molecules: CAMs, Cadherins

    3. Ephrins
  66. What are the 2 diffusible axon growth signals?
    1.  Chemoattraction

    2.  Chemorepulsion
  67. Extracellular matrix adhesion molecules:  give examples, where do they work, how do they work, and what do they do
    - Examples:  laminins, collagens, fibronectin

    - particularly important in embryonic periphery

    - interact with integrin receptors on growth cones

    - bind growth cone integrins trigger axon growth and elongation
  68. Cell adhesion molecules:  where are they located, how do they work, what do they do
    - Locations:  cell surface (axons, growth cones, glia) and within ECM

    - act as both ligands and receptors (bind together)

    - promote axonal extension and axon bundling
  69. Ephrins: what are they, how do they work
    - large family of ligands that bind with specific tyrosine kinase receptors (Ephs)

    - immature axons use ephrin-Eph binding to recognize appropiate pathways for extension and sites for synaptogenesis

    - in different situations, ephrin-Eph binding either promotes axong growth or limits axon growth via different signaling pathways
  70. What is chemoattraction?  Name the chemoattractant and its actions.
    - Chemoattraction - process by which tropic molecules guide axon growth toward source

    - Netrin:  acts at midline crossing points
  71. What is chemorepulsion? Name two classes of chemorepellants and their actions.
    - chemorepulsion - process by which chemorepellant molecules cause collapse of growth cone and block axon growth

    - Nogo:  produced by oligodendrocytes in adults, significant in injury response

    - slit, semaphorins - active during development
  72. What is meant by "selective synapse formation"?
    Neurons never form synapses with glial or connective tissue cells

    • Selective affinities exist between presynaptic and postsynaptic neurons and are:
    • - a major determinant of specific neuronal connectivity
    • - not absolute
    • - able to rearrange after injury
  73. What entities promote recognition of the postsynaptic site?
    CAMs, cadherins, and ephrins
  74. What happens once synaptic connectivity is established? Lost?
    Established - neurons become dependent on postysnaptic target cell for survival and maintenance

    Lost - presynaptic neuron will atrophy and die
  75. Trophic interactions:
    - are mediated by neurotrophins

    - determine size of neuronal populations during development

    - continue to play a role in neuron survival and function throughout life
    • 1. Presynaptic neuron
    • 2. Post synaptic neuron secretes neurotrophins
    • 3. Trophic factor receptors on presynaptic terminals
    • 4. Retrograde influence on gene expression
  76. What are ventral horn motor neurons regulated by?
    Availability of muscle fibers to innervate
  77. Neuron generation in embryos tend to produce excessive numbers of neurons.  What happens to neuron that do not establish appropriate synaptic connections?
    They do not receive trophic support and die by apoptosis
  78. Describe competitive synaptic interactions
    Initial polyneuronal innervation - each target cell receives input from multiple presynaptic neurons

    Activity-dependent competition reduces number of neuron contacting each target
  79. What is essential for neurite growth and elaboration in developing sympathetic neurons
    NGF (Nerve Growth Factor)
  80. What are irratative lesions?  What are some symptoms?
    Lesions that produce pathologic activity in the axon

    • Symptons:
    • - sensory: pain, tingling
    • - motor: muscle fasiculations, spasms
  81. What are destructive lesions.  What are some symptoms?
    Lesions that disrupt the integrity of the axon

    • Symptoms:
    • - sensory:  numbness, loss of sensation
    • - motor: weakness (paresis) or paralysis
  82. What are 3 types of neural repair?
    1.  Regrowth of peripheral nerve axons after axonal injury

    2.  Degeneration of injured CNS neurons, with limited recovery by astocytic scars

    3.  Limited replacement of lost neurons via neural stem cells (only in olfactory bulbs and hippocampus)
  83. What events follow injury to axons in peripheral nerves?
    - Axon distal to injury degenerates

    - Macrophages remove axonal debris

    - Schwann cells proliferate, express cell surface adhesion molecules and increase production of neurotrophic factors

    - neuronal cell body upregulates expression of genes that support axonal growth

    - Cut end of axon produces robust growth cone and many axonal sprouts

    - Axon extends toward target cell
  84. Compression vs cut injury in peripheral nerves
    Compression:  interrupts axons, but connective tissue sheath stays in tact, new axons grow down existing  connective tissue guides, great functional recovery

    Cut:  interrupts axons and connective tissue sheath, cut ends usually retract, appositions of cut ends and correct alignment of fascicles  essential for new axons to reach appropriate target, less functional recovery
  85. What series of events occurs following injury to axons in the CNS?
    - Axon distal to injury degenerates

    - slow clearance of axonal and myelin debris

    • - glia produced that discourage axonal growth
    •   -  semaphorins, slit for astrocytes
    •   -  NogoA from myelin membranes (oligodendocytes)

    - Neuronal cell body typically fails to upregulate gene expression that support axonal growth

    - cut end of axons produce small growth cones, and few axonal sprouts; upregulates receptors for semaphorin, ephrins, slit

    - astrocytic scars impede ability of axon to extend toward target
  86. What suggests that CNS provides a hostile environment for axonal growth, rather than an intrinsic inability to regenerate?
    Peripheral grafts.  Injured CNS neurons are able to extend new axons through peripheral nerve grafts, but growth stops when axons re-enter CNS (i.e. retinal axons)