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2011-12-05 17:33:12
Nervous Tissue Physiology

Nervous Tissue and Physiology
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  1. What are the main fxns of the nervous tissue:
    • maintain homeostasis
    • functionality
    • communication
    • coordination
  2. List the three types of nerves:
    • Motor: muscles
    • Sensory: CNS
    • Interneurons: connect CNS and PNS
  3. List the three divisions of the afferent divisions:
    • Visceral: carries signals from the heart, lungs, stomach, and urinary bladder
    • Somatic: carries signals from the skin, muscles, bones and joints
    • Speical: sight, taste, sounds, ect.
  4. List the two divisions of the efferent division:

    List the three divisions of the autonomic division of the efferent divison:
    • Autonomic: carries signals to glands, cardiac muscle, and smooth muscle
    • Somatic: carries signals to skeletal muscles

    • Autonomic divisions
    • Sympathetic: arouse body for action
    • Parasympathetic: calming effect
    • Enteric
  5. List the six characteristics of neurons:
    • Excitability: changes in environment
    • Conductivity: electrical signals
    • Secretion: neurotransmitters
    • No mitosis
    • Longevity
    • High metabolic rate: aerobic
  6. Define and Describe the Soma:
    • Definition: the control center of the neuron
    • Describe: 1 nucleus, 1 nucleolus, no centrioles
  7. Define Dendrites:
    thick branched processes that are the primary site for receiving signals from other neurons
  8. Define Axon Hillock:
    connects axon to the soma, site of signal initation (trigger zone)
  9. Define Axon:
    nerve fiber
  10. Define Nucleus:
    a group of cell bodies (somas) in the CNS
  11. Define Ganglia:
    a group of cell bodies in the PNS
  12. Define Tract:
    a bundle of axons (nerve fibers) in the CNS
  13. Define Nerve:
    bundle of axons (nerve fibers) in the PNS
  14. A neuron that has one axon and multiple dendrites, the most common type of neuron, is called:

  15. Neurons that have one axon and one dendrite are called:

  16. Neurons that only have one single process (an axon) leading away from the soma is called:

  17. _______ are the most common type of neuron
  18. Define neruoglia or glial cells:
    cells that bind neruons together and provide a supportive framework for the nervous tissue
  19. Describe the Fxn of the nervous system:
    • Sensory: ability to decect things (tactile receptors)
    • Intergration: decision process/store information
    • Motor: preform an action
  20. List the Periphereal Nervous system functional classification of neruons:
    • Afferent: Sensory neurons conduct signals from receptors to the CNS
    • Efferent: Motor neurons conduct signals from the CNS to effectors such as muscles and glands
  21. List the Central Nervous system fuctional classification of neurons:
    Interneurons: assosciation neurons are confined to the CNS
  22. Define, describe the fxns, and features of Neuroglia:
    • Definition: Supportive Cells
    • Fxn: Binds and supports neurons "neuroglue", transfer wastes and nutrients
    • Features: mitotic ( can divide), and Insulates neurons from other neurons ( neurons can't touch)
  23. List the Neuroglia of the CNS:
    • Astrocytes
    • Oligodendrocytes
    • Microglia
    • Ependymal
  24. List the Neuroglia of the PNS:
    • Schwann cells
    • Statellite ( regulate chemicals)
  25. Describe the structure, fxn, and location of Astrocytes:
    • Structure: "star shaped" b/c of extenstions going out, clings onto blood vessel and neuron
    • fxn: provides support, forms blood brain barrier, secret growth factors, regulates nurtients/wastes
    • location: CNS
  26. Describe the Astrocytes role in the Blood Brain Barrier:
    The blood does not go into the brain to the astrocytes bridges the gap
  27. Describe the structure, fxn and location of Ependymal cells:
    • Structure: cuboidal (similar to epithelium), no basement membrane
    • fxn: lines the cavity and secrets CSF into the interior
    • location: CNS
  28. Describe the structure, fxn and location of the microglia:
    • Structure: macrophages
    • fxn: cleans up debris, bacteria. if there is infection the cells multiply
    • location: CNS
  29. Describe the structure, fxn and location of oligodendrocytes:
    • structure: 20% protein, 80% lipids
    • fxn:secret myelin, act as barrier, insulates, increase conduction speed
    • location: CNS
  30. List the structure, fxn, and location of schwann cells:
    • structure: cell - cell membrane, nucleus, cytoplasm
    • fxn: myelin, wraps around axon in sections
    • location: PNS
  31. List the fxn and location of the Nodes of Ranvier:
    • fxn: unmyelinated spaces between cells
    • location: PNS and CNS
  32. Distinguish between neurons and glial cells:
    • Neurons
    • Excitablility
    • conductivity
    • serections (neurotransmitters)
    • longevity
    • no mitosis
    • high metabolic rate

    • Glial Cells
    • binds/supports neurons
    • miotic
    • insulate
    • transfer nutrients/wastes
  33. Describe what multiple sclerosis is and how it effects the nervous system:
    • Multiple sclerosis: "hard condition", oligodendrocytes are replace by scar tissue
    • Nervous system: nerve conduction is disrupted, autoimmune disorder triggered by a virus
    • Symptoms: speech defects, blindness, numbness
  34. what is an electrical potential? (include the word polarized in your answer)
    there is a seperation of charge across the membrane, in which one side is more electronegative, and one side more electropositive making the membrane polaized.
  35. List two ways in which electrial potential can be increased:
    • force increases with decreasing distance of charge seperation
    • force increases with the quantity of the charge
  36. List the factors that influence and maintain resting membrane potential:
    • Ion difference between ICF and ECF
    • membrane permability to ions
    • depolarization
    • repolarization
  37. The flow of sodium into a cell or potassium out of a cell is an example of :
  38. Which ion is responsible for depolarization? repolarization? hyperpolarization?
    • depolarization: Na+
    • repolarization: K+
    • hyperpolarization: K+, Cl-
  39. Which ion has a stronger influence on the membrane's charge? why?
    K+ has the strongest influence, the membrane is most permible to it.
  40. Compare and contrast local (graded potentials) and action potentials:
    • Local (graded) pontential
    • vary magnititude depending on what the stimulus is
    • can be summated
    • decrease with distance at thershold singal triggers
    • can be reversible (refractory peroid)
    • can be excitatory ( depolarizing) or inhibitory (hyperpolarizing)

    • Action Potentialsdoes not decrease with distance
    • can not summate
    • irreversible
  41. At what point does a local potential become and action potential?
    at threshold
  42. True/False: All local potentials are all or nothing and have uniform strength
    False: all action potentials are all or nothing adn have uniform strength.
  43. What division of the nervous system carries signals from the CNS to effectors such as muscles and glands?

    somatic sensory
    spinal cord
  44. The majority of cells in the nervous system are ________ which provide a supportive framework for nervous tissue.

    satellite cells
    multipolar neurons
    unmyelinated fibers
    glial cells
    anaxonic neurons
    glial cells
  45. Which of the following cell types is an important component of the blood-brain barrier and functions to nourish and regulate the composition of the extracellular fluid surrounding neurons?

    Schwann cell
    ependymal cells
    satellite cells
  46. ____ ions have the greatest influence on the resting membrane potential. In a typical neuron the resting membrane potential is about ______.

    K+ ; -70 mV
    Na+ ; +35 mV
    K+ ; +35 mV
    Ca2+ ; +35 mV
    ACh ; -70 mV
    Na+ ; -70 mV
    K+; -70 mV
  47. At resting membrane potential, the Na+ concentration is higher inside the cell than outside the cell.

  48. At resting membrane potential, the K+ concentration is higher inside the cell than outside the cell.

  49. Which of the following is FALSE regarding local potentials?

    The strength of a local potential decreases as it spreads from the point of stimulation.

    Local potentials are reversible if the stimulation stops before threshold is reached.

    Local potentials can be either excitatory (depolarizing) or inhibitory (hyperpolarizing).

    Local potentials, like action potentials, are "all-or-none": they either do not occur at all or exhibit the same peak voltage regardless of stimulus
    Local potentials, like action potentials, are "all-or-none": they either do not occur at all or exhibit the same peak voltage regardless of stimulus strength.
  50. List the events that occur before and during an action potential:
    • local potentials depolarize the membrane
    • threshold voltage is reached
    • volted-gated Na+ chanels open
    • voltage of the cell is positive
    • repolarization
    • membrane is hyperpolarized
    • resting membrane potential is restored
  51. Depolarization is caused by the movement of ____ ions _____ the cell.

    Na+ ; out of
    K+ ; into
    Na+ ; into
    Ca++ ; into
    K+ ; out of
    Ca++ ; out of
    Na+; into
  52. Repolarization is caused by the movement of ____ions ______the cell.

    Na+ ; into
    Na+ ; out of
    K+ ; out of
    Ca++ ; out of
    Ca++ ; into
    K+ ; into
    K+: out of
  53. Hyperpolarization is caused by the movement of ____ions _____the cell.

    K+ ; into
    Ca++ ; into
    Ca++ ; out of
    Na+ ; into
    K+ ; out of
    Na+ ; out of
    K+; out of
  54. Signal conduction in a nerve fiber is fastest in neurons that are:

    small and myelinated
    large and unmyelinated
    small and unmyelinated
    large and myelinated
    small and myelinated
  55. The _______ is the phase of an action potential in which no stimulus, no matter how strong, will trigger a new action potential.

    inhibitory period
    absolute refractory period
    excitatory period
    relative refractory period
    absolute refractory period
  56. how do anesthetics work to control pain?
    volted gated channels remain closed, RMP remains at -70mV, so the sensory signal isnt being transmitted
  57. Distinguish between absolute and relative refractory peiords?
    • absolute
    • the inbetween threshold
    • no stimulus can trigger an action potential

    • relative
    • hyperpolarization, below RMP
    • will need a stronger stimulus to trigger an action potential
  58. Describe the factors that affect the rate of impulse conduction along an axon:
    • the diameter of the nerve (bigger is better)
    • the presence or absence of myelin
  59. Distinguish between continuous and salatory conduction:
    • unmyelinated continuous (slow) conduction
    • Na+ leakage
    • anion attraction
    • non decremental, signal stays strong over a distance
    • regenerating AP along axon (new Na+ source)
    • aids in digestion regulation

    myelinated saltatory (fast ) conduction

    • AP is generated only at the node (myeling b/w nodes)
    • insulation: ions cant go in/out thru myelin, only when nerve is exposed can generate AP
    • signal is decremental( limited # of Na+ ions)
    • aids in motor fxn/sharp sensory
  60. Expalin what is ment by presynaptic and postsynaptic neuron:
    • presynaptic neruon: the neruon that the signal arrives at, and releases the neruotransmitter
    • postsynaptic neruon: the neuron that responds to the neruotransmitter

    • 1. local potential builds in nerver fiber with dendrites
    • 2. soma - on the other side of the soma is AP
    • 3. presynaptic neuron
    • 4. synaptic junction - neurotransmitter is released
    • 5. the next nerve responds to neurotransmitter
    • 6. repeats all the way to the brain

    * postsynaptic neuron is presynaptic neuron for the next neuron
  61. Describe the structure and fxn of chemical synapses:
    • structure: snyaptic knob, synaptic vessicles (contain neurotransmitters), synaptic cleft (space between receptors and postsynaptic neuron)
    • fxn: the way in which neruons communicate by neurotransmitters
  62. Describe the mechanisms used to clear neurotransmitters from synapses and why this is necessary:
    • Mechanisms
    • Diffusion into the ECF
    • Reuptake, amino acid (-) reabsorbtion
    • Degradation in synaptic cleft (breakdown enzymes)

    Why: postsynaptic neuro could continue firing indefinitely, causing a breakdown in physiological coordination
  63. Summarize the different classes of neurotransmitters:
    • Excitatory
    • ACh
    • Aspartic acid
    • gluatmic acid
    • epinephrine
    • norepiephrine
    • dopamine

    • inhibitory
    • amino acids
    • glycine
    • GABA

    • Situational
    • serotonin
    • histimine
  64. what are the three main types of neurotransmitters?

    which one is ACh?
    Excitatory, inhibitory, and situational

    ACh is excitatory
  65. Explain the difference between excitatory and inhibitatory postsnyaptic potentials and the mechanism by which each is generated:
    • Excitatory
    • EPSP (excitatory postsynaptic potential)
    • a change in voltage potential towards the threshold
    • Depolarization ( doesnt shoot up, only a slight amount of Na+ flowing in)
    • Potential is a little higher than normal (-70 mV vs. -60mV)
    • Neuron is most likely to fire

    • Inhibitatory
    • IPSP ( inhibitatory postsynaptic potential)
    • change in voltage potential goes away from threshold
    • Hyperpolarization( starts off more negative than RMP)
    • Neuron is less likely to fire ( will need a stronger signal)
  66. Explain the concept of summation and distinguish between temporal and spatial summation:
    summation: the process of adding up postsynaptic potentials and responding to their net effect, occurs in the trigger zone

    temporal summation: a single synapse genereates EPSP so quickly that each is generated before the previous one fadeds, allows EPSP to add up over time to a threshold voltage that triggers AP

    spatial summation: occurs when EPSP from several synapses add up to threshold at the axon hillock, several synapses acting together admit enought Na+ to reach threshold
  67. Put the following events in order:

    a. neurotransmitters (NT) travel across synaptic cleft
    b. Local potential occurs in soma
    c. voltage-gated calcium channels open
    d. membrane depolarzied to reach threshold at axon hillock
    e. threshold reached in postsynaptic neuron
    f. action potential occurs
    g. EPSP's summate
    h. NT released
    i. chemical, light, or heat stimulus occurs
    j. NTs open channels in postsynaptic neuron
    k. NTs open channels at the dendrite
    • i. chemical, light, or heat stimulus occurs
    • k. NTs open channels at the dendrite
    • b. Local potential occurs in soma
    • d. membrane depolarzied to reach threshold at axon hillock
    • f. action potential occurs
    • c. voltage-gated calcium channels open
    • h. NT released
    • a. neurotransmitters (NT) travel across synaptic cleft
    • j. NTs open channels in postsynaptic neuron
    • g. EPSP's summate
    • e. threshold reached in postsynaptic neuron
  68. what is the term used to describe a neuron's ability to process, recall and store information and make decisions?
  69. which of the following is in the correct order for the firing of an action potential?

    a. hyperpolarization, K+ channels open , threshold is reached, Na+ channels open
    b. Na+ channels open, K+ channels open, threshold is reached, hyperpolarization
    c. threshold is reached, hyperpolarization, k+ channels open, Na+ channels open
    d. threshold is reached, Na+ channels open, K+ channels open, hyperpolariztion
  70. which of the following is false regarding excitatory post snyaptic potenial (EPSP)?

    a. the membrane becomes deploarized with a single EPSP
    b. epsp are caused by the flow of positive ions out of the cell
    c. epsps make an action potenital more likely to occur
    d. epsp are local potentials that can summate
  71. action potentials are conducted most rapidly down axons that are:

    a. big and myelinated
    b. big and unmyelinated
    c. small and myelinated
    d. small and unmyelinated
  72. on a myelinated axon, the spaces between the myelin are called:

    a. nodes of ranvier
    b. internodes
    c. inital segments
    d. axon hillock
    e. neurolemma
  73. The myelination of nerves within the CNS is a role of the:

    a. astrocyes
    b. oligodendrocyte
    c. schwann cell
    d. ependymal cells
  74. which of the following best describes the relative refractory peroid of an action potenital?

    a. the time it takes to travel down the length of the axon
    b. the time it takes to jump from one node to another
    c. the phase in which no stimulation will generate an additoinal action potential
    d. the phase in which only a strong stimulation will generate an additional action potential