Worksheet V: The Neuron

1. List 4 functions of the nervous system.            _____________________________
                                                                            _____________________________
                                                                            _____________________________
                                                                            _____________________________

2. ______________________ is study of the normal functioning and disorders of the nervous system.

3.  The two main divisions of the nervous system are:        _____________________________
                                                                                            _____________________________
4.  The CNS includes the _____________________ and the _________________________.

5.  Identify the the divisions of the PNS based on the descriptions given below.
    a. Voluntary; runs from CNS to skeletal muscle.        _____________________________
    b.  Collects sensory information from receptors in the
    skin and skeletal muscle and sends to CNS.               _____________________________
    c.  Sends nerve impulses from receptors to CNS.       _____________________________
    d. Sends nerve impulses from the CNS to effectors.   _____________________________
    e.  Collects sensory information from receptors in the
    internal viscera and sends to CNS.                             _____________________________
    f.  Involuntary; from CNS to smooth and cardiac muscles
    and glands.                                                                 _____________________________
    g.  Division of ANS associated with fight or flight.   _____________________________
    h. Division of ANS associated with maintaining normal
    metabolism activities.                                                 _____________________________
            
6. Name the 2 most general cell types in the nervous system.    _____________________________  
                                                                                                    _____________________________

7. Identify the type of neuroglial cell based on the descriptions given below.
    a.  Star-shaped cells that regulate passage of molecules
    from blood to the brain; wrap around neurons and support. _________________________
    b.  Form myelin sheaths around axons in CNS; support.    ____________________________
    c.  Phagocytic cells that migrate throughout CNS;
    remove foreign and degenerative materials; thought to
    be involved in Down’s syndrome and Alzheimer’s disease.___________________________
    d. Flattened cells that support ganglia and control
    chemical environment within PNS.                                     ____________________________
    e.  Ciliated epithelial cells that line ventricles and central
    canal; help circulate cerebrospinal fluid.                             ____________________________
    f.  Form myelin sheath of PNS.                                          ____________________________
    g.  Important in axon repair; PNS.                                      ____________________________

8.  A neuron is composed of 3 main parts.  These are:        ____________________________
                                                                                            ____________________________
                                                                                            ____________________________

9.  Identify the part of the neuron based on the descriptions given below.
    a.  Granular rough endoplasmic reticulum-protein synthesis. ________________________
    b.  Long thin fibrils composed of microtubules and             
    microfilaments-support and transportation of nutrients.   ___________________________
    c. Contains most cytoplasm and organelles (e.g. nucleus). __________________________
    d.  Pigment associated with aging; harmless byproduct
    of lysosome activity.                                                    _____________________________
    e.   Highly branched thick extensions of cytoplasm.    _____________________________
    f.  Conduct impulse towards cell body.                        _____________________________
    g.  Often associated with receptors.                             _____________________________
    h.  Also called a nerve fiber.                                        _____________________________
    i.  Conducts impulses away from cell body.                _____________________________
    j.  Conical region of cell body where nerve impulses are
    started.                                                                         _____________________________
    k. Expanded terminal ends of an axon.                       _____________________________
    l.  Cytoplasm of an axon.                                            _____________________________
    m. 90 degree major side branches of an axon.            _____________________________
    n. Single, long, thin process leading out from cell body.___________________________
    o.  Membrane enclosed sacs that house neurotransmitters.__________________________
    p. Branched area of an axon collateral.                        _____________________________
    q.  Collective name for Schwann cells on an axon.     _____________________________
    r. Space between Schwann cells.                                _____________________________

10.  ________________ moves materials along an axon in the ______ stream at a rate of ____ per day or in the _____
stream at a rate of _____ mm per hour.

11.  Substances can move in either direction along an axon.  If the substances are sent outward towards the synaptic end
bulb it is called ________________ flow.  If substances are brought back towards the cell body, the event is called
________________ flow.
12.  A group of cell bodies outside the CNS is a(n):        ____________________________
13. A group of cell bodies inside the CNS is a(n):            ____________________________
14. A group of nerve fibers inside the CNS is a(n):        ____________________________
15. A group of nerve fibers outside the CNS is a(n):        ____________________________
16. Unmyelinated axons compose a substance called:        ____________________________
17. Myelinated axons compose a substance called:        ____________________________
18. Neurons are classified by 2 means.  They are:      
                                                                        ____________________________                                                                                                                                                                                                                ____________________________
19. Identify the kinds of neurons based on the descriptions given below.
    a.  Have one process extending from their cell body.        ____________________________
    b. Conduct nerve impulses from receptors to the CNS.     ___________________________
    c. Have one dendrite and one axon.                                  ____________________________
    d. Found in the retina of the eye, the inner ear, and
    olfactory cells.                                                                   ____________________________
    e. Sensory neurons are these kind of neurons.                  ____________________________
    f. Found in the brain and spinal cord.                               ____________________________   
    g. Have several dendrites and one axon.                          ____________________________
    h.  Conducts impulse from CNS to muscle or gland.        ____________________________
    i. Within CNS; Unite sensory to motor neurons.              ____________________________

20.  The __________________ is a connective tissue sheath around an entire nerve.
21. The ___________________ is a connective tissue sheath around a fascicle.
22.  The ___________________ is a connective tissue sheath around a nerve fiber.
23.  ______ ions are 28-30 times more concentrated inside the membrane than outside while ____ ions are
10-14 times more concentrated outside the membrane than inside.

24.  The outside of the membrane is ______ (+/-) and the inside is (+/-).  The membrane is said to
be:    _____________________________.

25. Three factors are responsible for the resting state of a nerve cell's membrane.  They are:
                                _____________________________
                                _____________________________
                                _____________________________
26.  The Na/K pump is what kind of macromolecule?        _____________________________
27.  Where is the Na/K pump  located?            _____________________________
28.  The Na/K pump pumps ____ (How many?) Na+ out for every _____ (How many?) K+ in.
29.  Gated channels are what kind of macromolecule?        _____________________________
30.   Where are the gated channels located?            _____________________________
31.  During the resting potential, potassium gated channels are __________ (more/less) leaky than Na+ gated channels.
32.  The outside of a nerve cell's membrane is positive relative to the inside.  This difference in potentialis referred to as the:                    _____________________________
33. The inside of a nerve cell's membrane averages ______ mV while the outside averages ______mV.
34. Nerve cells, like muscle cells, respond to stimuli; that is they are:________________________.
35.  Gated channels sensitive to changes in charge are said to be _______________sensitive while gated channels sensitive
to neurotransmitters are said to be ___________________ sensitive.
36.  A __a__ stimulus will initiate a nerve impulse from the __b__.  This stimulus causes the opening of
voltage-sensitive __c__ gated channels, increasing their permeability 10,000 times.  As __c__ ions rush in a
charge reversal occurs locally.  These __d__ (positively/negatively) charged ions are attracted to adjacent __e__
(positive/negative) regions, an event called __f__, triggering the opening of the next voltage-sensitive __c__ gated
channel.  This sequence continues as a wave of __g__ along the entire length of the axon.  As the internal charge
nears __h__ mV, __i__ gated channels close and __j__ gated channels open allowing __k__ ions __l__ (out/in).
This event, called __m__, helps restore the membrane to its original polarized state.  Both events, __g__ and __m__,
are called the __n__.
    a. ____________________________        h. ___________________________    
    b. ____________________________        i. ___________________________
    c. ____________________________        j. ____________________________
    d. ____________________________        k. ____________________________
    e. ____________________________        l. ____________________________
    f. _____________________________    m. ____________________________
    g. _____________________________    n. ___________________________

37. The ____________________________ period is the time during which a neuron cannot generate an impulse, not matter
how strong the stimulus.  It corresponds to the time when the ______ gated channels are _________________ (open/closed).

38.   The ____________________________ period is the time during which a neuron can generate an impulse,
but only with a stimulus greater in strength than threshold (i.e. with a suprathreshold stimulus).  It roughly corresponds to
the time when the ______ gated channels are _________________ (open/closed).

39. A nerve impulse, initiated from the ____________________ , travels in __________ (one/both) direction(s) to the end
regions of the axon called ____________________________.

40.  A threshold stimulus causes a nerve impulse to travel the full length of the axon while a subthreshold stimulus generates
no impulse.  This phenomenon is called the: ___________________________________.  Two kinds of cells act this way. 
They are: __________________________ and ____________________.

41.  Myelinated axons have voltage-sensitive gated channels located in the: _____________________.   Because of this extra
spacing between channels, the charge shifts appear to jump from one group of channels to the next.  This type of conduction
is called ___________________ conduction.

42.  Name 3 factors that increase the speed of a nerve impulse.                                                                                                                                                                                                    ____________________________
                                ____________________________
                                ____________________________
43. Identify the type of nerve fiber (A, B, C, D, etc.) based on the descriptions given below.
    a. Sensory and motor neurons.                                     ____________________________   
    b. Preganglionic nerve fibers; white matter CNS.        ____________________________   
    c. Large diameter and heavily myelinated.                  ____________________________   
    d. Speeds of 130 m/sec.                                              ____________________________   
    e.  Speeds of 0.5 m/sec.                                              ____________________________
    f. Postganglionic nerve fibers; gray matter of CNS & PNS.________________________
    g. Speeds of 10 m/sec.                                                ____________________________
    h. Unmyelinated.                                                        ____________________________
    i. Medium diameter and lightly myelinated.               ____________________________

44. A junction between two neurons is called a(n):        ____________________________

45. A junction between a muscle and nerve cell is called a(n)    ____________________________

46. A junction between a gland and nerve cell is called a(n):    ____________________________

47. List 3 functions of synapses.                ____________________________
                                                                    ____________________________
                                                                    ____________________________
48. Name 2 general kinds of synapses.                  ____________________________
                                                                               ____________________________
49. The most common (in adults) of these general synapses is the: __________________________.

50.  The space between 2 cells at a synapse is called the:    ____________________________

51.  The neuron that delivers the impulse to the synapse is referred to as the __a__ neuron while the neuron that takes
the impulse away from the synapse is referred to as the __b__ neuron.  If the axon of the __a__ neuron meets the dendrites
of a __b__ neuron the synapse is called __c__.  If the axon of the __a__ neuron meets the cell body of a __b__ neuron the
synapse is called __d__.  If the axon of the __a__ neuron meets the axon of a __b__ neuron the synapse is called __e__.
    a. ____________________________        d. ___________________________
    b. ____________________________        e. ___________________________
    c. ____________________________

52.  __a__ are made by the neuron, usually from __b__.  They are stored in __c__ in the enlarged terminal endings of the a
xon called __d__.  The __c__ release their __a__ in response to a __e__ ion influx into the __d__ .  The process whereby
the __c__ release their __a__ into the __f__ is called __g__.  The __a__ diffuses across the __f__ and binds to receptors on
the __h__ membrane.   If the receptors cause sodium gated channels to open, the postsynaptic neuron's internal polarity will
be made __i__ (more/less) negative bringing/driving the postsynaptic neuron's membrane potential __j__ (closer to/further
away from) threshold.  This change of the resting potential __k__ (closer to/further away from)  threshold is called a(n) __l__. 
However, if the receptors cause potassium and/or chloride ion gated channels to open, the postsynaptic neuron's internal
polarity will be made __m__ (more/less) negative bringing/driving the postsynaptic neuron's membrane potential __n__
(closer to/further away from) threshold.  This change of the resting potential __o__ (closer to/further away from)  threshold is
called a(n) __p__.
    a. ____________________________        i. ___________________________    
    b. ____________________________        j. ___________________________
    c. ____________________________        k. ____________________________
    d. ____________________________        l. ____________________________
    e. ____________________________        m. ___________________________
    f. _____________________________      n. ____________________________
    g. ____________________________        o. ____________________________
    h. ____________________________        p. ____________________________

53.  If both Na+ and K+ gated channels are opened at the same time the resting potential will be made _________ (more/less)
negative. This is because _____ ions move in more rapidly than _____ ions move out.

54. The time for an impulse to cross the synaptic cleft is called: ____________________________.
55.  Thousands of successive impulses will deplete neurotransmitter stores and cause the neuron to lose polarity.  This event is called:                _____________________________.

56. A single nerve impulse in the presynaptic neuron __a__ (can/cannot) cause a nerve impulse in the postsynaptic neuron.
However, the effects of several successive or simultaneous impulses can be added.  __b__ is when neurotransmitter builds
up because of several presynaptic neurons firing at the same time.  __c__ is when neurotransmitter build up is caused by one
presynaptic neuron firing in succession.  If the number of EPSPs is greater than the number of IPSPs and the sum is less than
threshold, then __d__ (no nerve impulse is generated/a nerve impulse is generated).  If the number of EPSPs is greater than the
number of IPSPs and the sum is greater than threshold, then __e__ (no/a) nerve impulse is generated.  If the number of IPSPs is
greater than the number of EPSPs, then __f__ (no/a) nerve impulse is generated.
    a. _____________________________        d. ___________________________
    b. _____________________________        e. ___________________________
    c. _____________________________        f. ____________________________

57. The most common and best studied neurotransmitter is:    _____________________________.

58.  ACh is released in units called __a__.  Once ACh binds to receptors on the postsynaptic membrane, the enzyme __b__ breaks
ACh into __c__ and __d__.  The enzyme __e__ combines acetyl CoA and __d__ to form ACh and CoA.  ACh is almost always
__f__ (excitatory/inhibitory) except when released by the vagus nerve where it is __g__ (excitatory/inhibitory).
    a. _____________________________        e. ___________________________
    b. _____________________________        f. ___________________________
    c. _____________________________        g. ____________________________
    d. _____________________________        
59. Identify the kind of neurotransmitter based on the descriptions given below.
    a.  Formed from acetylCoA and choline.                      ______________________________
    b.  Released in the spinal cord and retina; inhibitory.    ______________________________
    c.  Made from the amino acid glutamic acid.                 _____________________________
    d. Made from the amino acid tyrosine; released at some
    myoneural (smooth muscle) and neuroglandular jcts.    _____________________________
    e. Inhibitory in CNS; Purkinje cells of cerebellum.        _____________________________
    f.  Important NT in cerebral nuclei; subconscious
    control of skeletal muscles.                                            _____________________________
    g. Release at all myoneural junctions involving
    skeletal muscle.                                                              _____________________________
    h. Valium enahances action of this NT.                         _____________________________
    i.  Strychnine blocks receptors for this NT; causes
    uncontrolled muscle spasms.                                          _____________________________
    j. Huntington's Chorea caused by decreased amounts
    of this NT.                                                                      _____________________________
    k. Important NT in mood, sensory perception, and sleep.  ___________________________
    l.   Chains of 2-40 aa found in brain.                             _____________________________

60. Neuron cell bodies lose their ____________________  at  approximately 6 months.

61. _____________________ cells create a passageway for the damaged axon ends to grow through and rejoin.

62. Compare temporal to spatial summation. __________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________

63. Draw a graph with correctly labeled axes showing an action potential, EPSP, and IPSP. _______








64. Draw a graph (and verbally describe) with correctly labeled axes showing how EPSPs can lead to an action potential. ______________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________







65. How does anterograde flow differ from retrograde transport? _____________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________

66. How is the resting potential established in a neuron and muscle cell? _____________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________

67. How is an action potential propagated along the axon towards the synaptic end bulb? ________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________

68. Summarize the events at the synapse. ____________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________

69. Why are chemically-sensitive gated channels associated with receptors at the synapse and voltage-sensitive
channels found along the axon? _______________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________

70. How do organophosphate pesticides work and what initial symptoms would occur in humans that ingest
these chemicals? __________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________

71. In terms of a gated channel what is the difference between a threshold stimulus and a subthreshold stimulus? _____________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
_____________________________________________________________________________

72. Why (how) does a myelinated axon speed up a nerve impulse compared to an unmyelinated axon?
_____________________________________________________________________________
______________________________________________________________________________
____________________________________________________________________________

73. A group of interconnected neurons with specific functions is called a(n): ___________________.




74. List five patterns found in neuronal pools.
                                _____________________________
                                _____________________________
                                _____________________________
                                _____________________________
                                _____________________________

75. Identify the kind of neuronal pool described below.
    a. Information relayed in stepwise fashion.......    __________________________________
    b. Several neurons or neuronal pools process
    same information at the same time.................    __________________________________
    c. Collateral branches of an axon synapse back
    on presynaptic neurons and further enhance the
    impulse...........................................................    __________________________________
    d. Spread of information from one neuron to
    several neurons..............................................    __________________________________
    e. Several neurons synapse on the same post-
    synaptic neuron............................................... ___________________________________

76. Describe the steps of axon repair in the PNS.  What prevents CNS neurons from repairing as well as PNS neurons?