Nervous System

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Author:
ash3ach
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218940
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Nervous System
Updated:
2013-05-10 12:40:44
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Life 103
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test 4
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  1. neurons
    • are nerve cells that transfer information within the body
    • Neurons use two types of signals to communicate: electrical signals (long-distance) and chemical signals (short-distance)
  2. ganglia
    Processing of information takes place in simple clusters of neurons called ganglia or a more complex organization of neurons called a brain
  3. Nervous systems process information in three stages which are?
    sensory input, integration, and motor output
  4. sensory neurons
    Sensors detect external stimuli and internal conditions and transmit information along sensory neurons
  5. Sensory information is sent to the brain or ganglia, where what integrate the information
    interneurons
  6. Motor output leaves the brain or ganglia via what, which trigger muscle or gland activity
    motor neurons
  7. central nervous system (CNS)
    integration takes place; this includes the brain and a nerve cord
  8. peripheral nervous system (PNS
    brings information into and out of the CNS
  9. Most of a neuron’s organelles are in the what?
    cell body
  10. dendrites
    highly branched extensions that receive signals from other neurons
  11. axon
    an axon joins the cell body at the what?
    • typically a much longer extension that transmits signals to other cells at synapses
    • An axon joins the cell body at the axon hillock
  12. neuron
  13. synapse
    junction between an axon and another cell
  14. synaptic terminal
    of one axon passes information across the synapse in the form of chemical messengers called neurotransmitters
  15. chemical messenger
    neurotransmitters
  16. Information is transmitted from a what cell to a what cell?
    Information is transmitted from a presynaptic cell (a neuron) to a postsynaptic cell (a neuron, muscle, or gland cell)
  17. Most neurons are nourished or insulated by cells called
    glia cells  (nurse cells)
  18. membrane potential
    • Every cell has a voltage (difference in electrical charge) across its plasma membrane called a membrane potential
    • Messages are transmitted as changes in membrane potential
  19. resting potential
    The resting potential is the membrane potential of a neuron not sending signals
  20. An action potential occurs if a stimulus causes the membrane voltage to cross a particular
    threshold
  21. An action potential is a brief all-or-none what of a neuron’s plasma membrane
    depolarization
  22. Action potentials are signals that carry information along what?
    axons
  23. In a mammalian neuron at resting potential, the concentration of what+ is greater inside the cell, while the concentration of what+ is greater outside the cell
    • K+
    • Na+
  24. Sodium-potassium pumps use the energy of ATP to maintain these K+ and Na+ gradients across the plasma membrane
    These concentration gradients represents what?
    the chemical potential energy
  25. The opening of what in the plasma membrane converts chemical potential to electrical potential
    ion channels
  26. A neuron at what potential contains many open K+ channels and fewer open Na+ channels; K+ diffuses out of the cell
    resting
  27. Anions trapped inside the cell contribute to the what charge within the neuron
    negative
  28. Neurons contain what that open or close in response to stimuli
    gated ion channels
  29. action potential
  30. refractory period
    • after an action potential, a second action potential cannot be initiated
    • The refractory period is a result of a temporary inactivation of the Na+ channels
    • Inactivated Na+ channels behind the zone of depolarization prevent the action potential from traveling backwards
  31. Action potentials travel in only one direction which is?
    toward the synaptic terminals
  32. The speed of an action potential increases with the axon’s
    diameter
  33. myelin sheath
    • In vertebrates, axons are insulated by a myelin sheath, which causes an action potential’s speed to increase
    • made by glia
  34. what are the 2 types of glia cells that make the myelin sheath?
    oligodendrocytes in the CNS and Schwann cells in the PNS
  35. Schwann cell
  36. nodes of Ranvier
    Action potentials are formed only at nodes of Ranvier, gaps in the myelin sheath where voltage-gated Na+ channels are found
  37. saltatory conduction
    Action potentials in myelinated axons jump between the nodes of Ranvier in a process called saltatory conduction
  38. Saltatory conduction
  39. electrical synapses
    At electrical synapses, the electrical current flows from one neuron to another
  40. chemical synapses
    • At chemical synapses, a chemical neurotransmitter carries information across the gap junction
    • Most synapses are chemical synapses
  41. The presynaptic neuron synthesizes and packages the neurotransmitter in what located in the synaptic terminal
    synaptic vesicles
  42. The action potential causes the release of the what
    neurotransmitter
  43. synaptic cleft
    The neurotransmitter diffuses across the synaptic cleft and is received by the postsynaptic cell
  44. chemical synapse
  45. Excitatory postsynaptic potentials (EPSPs)
    depolarizations that bring the membrane potential toward threshold
  46. Inhibitory postsynaptic potentials (IPSPs)
    are hyperpolarizations that move the membrane potential farther from threshold
  47. Unlike action potentials, postsynaptic potentials are graded and do not what
    regenerate
  48. Most neurons have many synapses on their what and what?
    dendrites and cell body
  49. A single EPSP is usually too small to trigger an action potential in a
    postsynaptic neuron
  50. temporal summation
    If two EPSPs are produced in rapid succession, an effect called temporal summation occurs
  51. The same neurotransmitter can produce different effects in different types of cells
    there are 5 classes of neurotransmitters what are they?
    • acetylcholine
    • biogenic amines
    • amino acids
    • neuropeptides
    • gases
  52. acetylcholine
    • a common neurotransmitter in vertebrates and invertebrates
    • In vertebrates it is usually an excitatory transmitter
    • One proposed cause of Alzheimer's disease is reduced synthesis of Acetlcholine
  53. what 3 drugs affect receptors?
    • nicotine
    • dextromethorphan
    • atropine
  54. biogenic amines (4)
    • epinephrine
    • norepinephrine
    • dopamine
    • serotonin
    • They are active in the CNS and PNS
    • Dopamine used in reward driven learning–Cocaine and methamphetamine act on dopamine receptors
    • Diseases associated with dopamine include schizophrenia and ADHD
  55. Two amino acids are known to function as major neurotransmitters in the CNS:
    • gamma-aminobutyric acid (GABA)
    • glutamate
    • GABA is never incorporated into a protein
    • GABA is inhibitory
    • Glutamate is excitatory
  56. Several neuropeptides, relatively short chains of amino acids, also function as neurotransmitters
    they include what 2?
    • Neuropeptides include substance P and endorphins, which both affect our perception of pain
    • Opiates bind to the same receptors as endorphins and can be used as painkillers
    • Naked mole rats lack sensitivity to substance P and thus insensitive to pain on their skin

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