Nervous System

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mdottery
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212514
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Nervous System
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2013-04-10 20:53:57
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Nervous system
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Nervous system
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  1. What does the Central Nervous system contain?
    Brain and spinal chord.
  2. What does the Peripheral Nervous system contain?
    cranial nerves, spinal nerves, sensory receptors, ganglia, somatic nervous system, sensory receptors, enteric nervous system, and autonomic nervous system.
  3. What does the nervous system do?
    Maintain homeostasis and integrate all body activities.
  4. What is a neuron contain?
    Cell body, nissl bodies, dendrites, axon, and axon hillock.
  5. What are the classified structures of neurons?
    Multipolar(several dendrites and one axon), bipolar(one dendrite and one axon), and unipolar(one process arising from the cell body that branches into two axon-like processes).
  6. What are the classified functions of neurons?
    Sensory neurons, motor neurons, and interneurons.
  7. What neuroglia is contained in CNS?
    Astrocytes(helps form blood brain barrier), Oligodendrocytes(produces myelin sheath), microglia(carry on phagocytosis) and ependymal cells(produce cerebrospinal fluid and line ventricles of the brain).
  8. What neuroglia is contained in PNS?
    Schwann cells(Forms myelin sheath)

    and

    Satellite cells(provides structure, flat neuroglial cells that surround cell bodies of ganglia and exchange of material)
  9. What are nodes of ranvier?
    unmyelinated gaps that occur at intervals along an axon
  10. What are neurotransmitters?
    Neurotransmitters bind to receptors and causes a voltage membrane difference by depolarization and re-polarization of the membrane potential.

    • The graded or action potential at
    • the end of the axon triggers the release of the neurotransmitters into the synaptic cleft
  11. What is the difference between myelinated and unmyelinated
    One contains and myelin sheath and the other doesn't
  12. List the levels of organization of the nervous system with functions
    CNS and PNS

    Sub divisions of the pns and functions

    -somatic nervous system (sns) voluntary:controls the skeletal muscles(motor)

    Automatic nervous system (ans) involuntary: affects the heart  and digestive system(motor)

    Enteric nervous system (ens) involuntary
  13. List the histology of the nervous tissue
    • Nervous tissues are designed to
    • transmit electrical impulses and includes:

    o    cell body--analyzes incoming information

    o    dendrites--receives incoming information

    o    axon--transmits information to other cells

    • o    neuroglia cells--protects,protects and
    • nourishes the neurons

    • o   myelin sheath--allows axons to send faster
    • signals

    o    terminal--synaptic ends
  14. What structure does the myelin sheath have?
    wrap around axons
  15. What are graded potentials?
    opening or cloosing of ligand-gated and mechanically gated channels in response to a stimulus
  16. How does grade potentials begin
    Responds to environmental stimulus
  17. What is a chemical synapse?
    impulses from a neuron to another cell through a synaptic cleft
  18. What is a threshold stimulus?
    a stimulus that is just strong enough to depolarize the membrane to threshold.
  19. What are post-synaptic neurons and pre-synaptic neurons?
    One carries impulses away from a synapse and the other carries an impulse toward a synapse
  20. What is a electrical synapse?
    impulses that conduct directly between the plasma membranes through gap junctions
  21. What are Excitatory postsynaptic potential(EpSP) and Inhibitory postsynaptic potential(IPSP)?
    EPSP is a depolarizing postsynaptic potential and IPSP is a hyperpolarizing postsynaptic potential
  22. What initiates graded potentials in
    sensory neurons, interneurons and motor neurons?
    Evironmental stimulus initiates sensory neurons

    neuro transmitters initiates interneurons

    neuro transmitters initiates motor neurons
  23. What is stimulus?
    Any stress that changes a controlled condition, excites a sensory receptor, muscle or nueron
  24. The action potential is an all-or-none
    phenomenon. Explain
    Once threshold depolarization occurs, voltage-gated channels open, and an action potential that is always the same size occurs
  25. What is a Resting membrane potential?
    • Comes from a electrical voltage, When the membrane sees no
    • action potentials and remains at a constant -70 mv
  26. What is Depolarization?
    • Depolarization-when a response makes the membrane less polarized(inside less negative)
    •  The first stage of
    • an action potential where voltage gated Na+ channels quickly open and sodium rushes into the cell, making the inside of the cell more positive than the resting membranes potential.
  27. What are action potentials and graded potentials?
    Action potentials-rapid electrical events occurring in two phases:depolarizing phase and repolarizing phase.

    Graded potentials-the opening or closing of ligand-gated and mechanically gated channels in response to stimuli
  28. What is a nerve impulse?
    A wave of depolarization and repolarization that self-propogates along the plasma membrane of a neuron
  29. What is repolarization?
    Repolarization-When the restingmembrane comes back to a resting state  of -70mv. Na+ and K+ are at equallibum
  30. Explain Hyperpolarization
    Hyperpolarization- when a response makes the membrane more polarized(inside more negative)where voltage gated K+ channels open and potassium goes out of the cell, making the outside become more negative than the resting membranes potential.
  31. Compare graded potentials with action potential
    • Graded potentials are: 
    • stimulated by sensory neurons, occur in the dendrites, weak potentials, communicate with other close neurons, may or may not cause a change in the membrane, has ion gates that open one at a time, unless there is a strong stimulus then all open to cause an action potential


    • Action potentials are: all or none potential, impulses are strong enough to cause change
    • in the membrane, has voltage gates that allow Na+ to enter and K= to exit the neuron
  32. What are the subdivisions of PNS?
    • Motor neurons:
    • Sympathetic nervous system --controls the activity of the heart (fight orflight)Parasympathetic nervous system---controls the body for rest and repair
  33. Summarize the events that take place
    during one action potential.
     ions, ion channels, gates and neurotransmitters have in propagation of an action potential?
    • Membrane resting state of -70 mv
    • sensory receptors detect an environmental stimuli at the
    • dendrites as graded potential

    graded potential nerve impulse travels down the neuron as neurotranmitters exit through the synaptic cleft.

    • neurotransmitters receptors receive the chemical stimuli if the chemical stimuli is strong membrane threshold will be
    • met -70mv to -55mv 

    • Na+ voltage gates open allowing Na+ to rush into the cell
    • depolarization occurs
    • ***action potential*** 
    • Na+ gates close

    • k+ ion gates open allowing it to exit the cell
    •  repolarization of the membrane
    • sodium/potassium pump begins to pump 3 Na+ ions out of the
    • cell and 2 k+ ions back into the cell 

    cell returns to a resting state of -70 m
  34. Describe the conditions that exist across the neuronal membrane during the resting state.
    A neuron has an electrical and chemical gradient across its outer cell membrane.

    More positively charged Na+ on the outside of the membrane and more negatively charged on the inside K+ of the membrane, because of the sodium/potassium pump,that moves 3 Na+ ions out for every 2k+ ions moving in.

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