neurons

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jen_scott09
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83004
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neurons
Updated:
2011-05-01 22:39:11
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neural tissue
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chapter 12
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  1. ´╗┐List 3 primary fxns of the nervous system?
    • Sense - get info
    • Analyze - sort and process info received (linked to experience)
    • Effect - tell body what to do in response
  2. List 2 structural divisions of nervous system and major characterists of each
    • Central Nervous System - CNS
    • Neural tracts and no CT sheaths
    • Peripheral Nervous System - PNS
    • Nerves and have CT sheaths
  3. List 2 structural divisions of CNS and their fxns
    • Spinal cord
    • Sort info
    • Relay info
    • Basic reflex processing
    • Brain
    • Sort
    • Relay info
    • Reflex processing
    • Memory
    • Language
    • Homeostasis
  4. Briefly define Peripheral Nervous System (PNS)
    all neural tissue outside the CNS. It delivers sensory information to the CNS and carries motor commands to peripheral tissue and systems.
  5. List 2 Structural divisions of PNS and major characteristic
    • Cranial Nerves are nerves connected to the brain.
    • Spinal Nervesare nerves connected to the spinal cord
  6. List 3 functional divisions of PNS
    • Afferent Neuron Division
    • Efferent Neuron Division
    • Interneuron Divison
  7. Define Afferent Neuron Division
    • (Sensory)
    • a division of PNS that brings sensory information to CNS from receptors in peripheral tissues and organs
  8. Define Efferent Neuron Division
    • (Motor)
    • a division of PNS that carries motor commands away from CNS to muscles, glands and adipose tissue
  9. List 2 divisions of the Efferent division
    • Somatic Nervous System (SNS)
    • Autonomic Nervous System (ANS)
  10. What is the fxn of the Somatic Nervous System
    Control skeletal muscles, both voluntary and involuntary
  11. What is another name for involuntary muscle contraction
    Reflex
  12. What is the fxn of the Autonomic Nervous System
    also called the visceral motor system, it provides automatic regulation organs and organ systems at the subconscious level
  13. Define Interneuron Division
    they are asociation neurons and are most numerous neurons in body. Nost associated with the CNS but some are autonomic ganglia. They are responsible for distribution of sensory information and the coordination of motor activity.
  14. List 2 divisions of the ANS
    • Sympathetic - speeds up heart rate
    • Parasympathetic Division - slows down heart rate
  15. Whats a soma?
    cell body of neuron
  16. Whats the fxn of the cell body
    • Houses nucleus and perikaryon
    • receives and processes info
  17. Whats the fxn of the dendrites
    Receive info from other neurons
  18. Whats the axon and its fxn
    its the "tail" of the neuron that is capable of spreading and electrical impulse known as an action potential
  19. Describe hillock
    the "neck" area of the neuron where the axon attaches to the soma
  20. Describe axon collateral
    collective brances that extend from the main axon
  21. Describe axon terminal
    very end of axon or telodendria aka. synaptic terminals
  22. What is myelin made of
    lipids
  23. What is the fxn of myelin
    insulate and speed the AP along the axon
  24. What CNS neuroglial cell produces myelin
    oligodendrocytes
  25. What PNS neuroglial cell produces myelin
    Schwann cells
  26. What is a node of Ranvier and what material is not present in the node area?
    the gaps in myelin on the axon. They are there for ion channels to continue electrical currents.
  27. What structures are found in node of Ranvier
    ion channels
  28. What is saltotory propagation
    myelinated fibers. AP jumps from node of Ranvier to node of Ranvier. Because it jumps, it is much faster than non-mylinated. uses less E cuz contacts less surface area
  29. What is continuous propagation
    non-myelinated fibers. covers/depolarizes entire length of axon. requires more ion channels therefore uses more E. MUCH slower than saltatory propagation
  30. List 3 structural types of neurons
    • Unipolar
    • Bipolar
    • Multipolar
  31. Describe unipolar neurons
    one process attached to cell body that splits into receiving and sending. found in sensory areas like skin for touch and temp
  32. Describe bipolar neurons
    2 distinct processes off the soma, one for sending and one for receiving. found in sensory areas (eyes, mouth, nose) for senses.
  33. Describe multipolar neurons
    The "common neuron". multiple dendrites and a single axon. All motor and intermeurons and some sensory neurons.
  34. List 4 kinds of neuroglial cells in CNS
    • Ependymal cells
    • Astrocytes
    • Oligodendrocytes
    • Microglia
  35. List the 2 kinds of neuroglial cells in PNS
    • Satellite cells
    • Schwann Cells
  36. Define Ependymal Cells
    located in space around central canal of central canal of spinal cord and in spaces of brain. Helps make cerebral spinal fluid and acts as filter and blood-brain barrier
  37. Define Astrocytes
    largest and most numerous in CNS, they maintin a stable environment for neurons, fill in damaged areas of CNS and forms scar tissue after injury
  38. Define Oligodendrocytes
    Produce myelin in the CNS and physically support and organize CNS
  39. Define Microglia
    sm glial cell that fxns as phagocytes (clean up crew)
  40. Define Satellite cells
    poduce myelin for neurons and assist in healing process in PNS
  41. Define ganglia
    cells that support nuerons
  42. Define Schwann Cells
    found in ganglia, they produce myelin for neurons in PNS as well as assist in healing
  43. What is white matter
    myelinated neuro tissue in CNS such as axons, Tracts and Nerves.
  44. What is grey matter
    non myelinated neuro tissue in CNS including somas, dendrites, some axons and are found at sites of connection processing - areas will lots of cell bodies like on the surface of the brain and in the ctr of the spinal cord
  45. Describe the Na+ chem concentration gradient and K+ concentration gradient across cell membrane and why is it important
    • Extra cellular fluid (ECF) - high levels of Na+, Cl- and Ca2+ ions
    • Intra cellular fluid (ICF) - high levels of K+ and negatively charged proteins (Pr-)
    • Important because it creates potential energy because of the differences in charges
  46. What role does the sodium and potassium pump have in setting up, maintaining and restoring resting membrane potential?
    High level of Potassium ions within a cell at rest keep a neg charge while a high level of sodium outside the cell make it a + charge thus creating a polarized neuron. It is these 2 ions that control the set up, maintaining and restoring resting membrane potential
  47. Define leakage channels
    passive channels that are always open but are ion specific. They are located on the plasma membrane
  48. What do leakage channels have to do with cell membrane potential
    They maintain the resting Resting membrane potential
  49. What are 3 types of gated channels
    • chemically gated channels
    • mechanically gated channels
    • voltage gated channels
  50. What are some things that act as keys for gated channels
    NT and hormones. ACh common key
  51. What is depolarization
    Any shift from resting potential toward a more positive potential
  52. What are 2 common ions that will depolarize a cell
    Na+ or Ca+2
  53. Define threshold stimulus
    stimulus with depolarization large enough to open voltage-gated channels which initiates an action potential
  54. What ion channels open and which close during repolarization?
    Na+ channels close and K+ channels open
  55. Define hyperpolarization
    • making the inside of the cell more negative than RMP
    • Move + ions like K+ out of cell or - ions like Cl- into cell
  56. Describe Type A nerve fibers
    lg diameter and myelinated. FAST (140m/sec). Usually deal with balance and protective reflexes
  57. Describe Type B fibers
    sm in diameter and myelinated. Not as fast as A but still (18m/sec). found for heart rate, breathing, muscles and facial
  58. Describe Type C fibers
    smallest and non-myelinated. Slowest (1m/sec). internal organ control
  59. Describe the structure of an Electrical synapse
    the pre and post synaptic membranes are locked together at gap junctions thus resulting in AP quickly and efficiently propagating from one cell to the next. Rare except in heart, some areas of brain and in the eye.
  60. What is biggest problem with Electrical synapse
    reliability
  61. Define Chemical synapse
    pre and post synaptic neurons do not touch. Space in between is called synaptic cleft
  62. Define Synaptic delay
    the time it takes signal to cross cleft and NT to bind to post synaptic cell
  63. Define post synaptic potential
    Electrical potential generated in the post-synaptic cell in response to NT. Graded potentials and can be Excitatory Post-synaptic potential (EPSP) or Inhibitory Post-synaptic Potential (IPSP)
  64. What does Graded mean
    The size of the stimulus determines the local depolarization or hyperpolarization

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