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?