chapter 2 Flashcards
(115 cards)
1
Q
two kinds of cells in nervous system
A
neurons and glia
2
Q
santiago ramon y cajal demonstrated that
A
neurons are separate from one another
3
Q
neurons differ more strongly from other body cells in their
A
shape
4
Q
which chemicals flow most freely across a cell membrae
A
water, oxygen, co2
5
Q
chemicals that cannot flow freely across a cell membrane enter a neuron through
A
specialized protein channels
6
Q
which of the following is most likely to cross the membrane by simple diffusion
A
small, uncharged particles
7
Q
where do the metabolic activities occur that provide energy for all other activities of the cell
A
mitochondria
8
Q
the endoplasmic reticulum is
A
network of thin tubes that transport newly synthesized proteins
9
Q
what receives excitation from other neurons and conducts impulses to muscle or gland cells
A
motor neurons
10
Q
dendrites
A
are branching fibers that get narrower near the end
11
Q
the surface of a dendrite is lines with specialized junctions through which the dendrite receives info from other neurons. what are these junctions called
A
synaptic receptors
12
Q
which of the following is not a characteristic of a dendrite
A
it is in contact with dendrites of other neurons
13
Q
some dendrites contain additional short outgrowths called
A
dendritic spines
14
Q
dendritic spines
A
increase the surface area available for synapses
15
Q
incoming synapses are primarily found on
A
dendrites and cell bodies
16
Q
the information sender of the neuron conveying an impulse toward either other neurons or a gland or muscle is called the
A
axon
17
Q
which of the following is the correct order of transmission of information within a neuron
A
dendrite, cell body, axon
18
Q
compared to dendrites, axons usually
A
are covered with myelin sheath
19
Q
nodes of ranvier are
A
gaps in the myelin of axons
20
Q
a presynaptic terminal is also known as
A
an end bulb
21
Q
which of the following is not true of axons
A
they carry information towards the soma (cell body)
22
Q
what is the point from which an axon releases chemicals into the synapse
A
presynaptic terminal
23
Q
an axon has many branches, each of which swells at its tip. these are known as
A
presynaptic terminals
24
Q
an axon releases chemicals
A
into the junction between neurons
25
a neuron can have any number of ___ but only one ___
dendrite; axon
26
as a general rule, where do axons convey information
away from the cell body
27
which of the following is not a characteristic of an axon
carries info toward cell body
28
if you were to accidentally touch a hot stove with your hand, you would quickly pull your hand away. the information carried to the muscle in your arm to make them contract was carried by
efferent neurons
29
if all of a neurons dendrites or axons were contained within the spinal cord it would be considered a(n)
intrinsic neuron
30
what would a neuron in the pons be called that receives information only from other cells in the pons and sends information only to other cells in the pons
intrinsic
31
glial cells?
do not transmit information over long distances
32
which of the following is a characteristic of glial cells in the human brain
they are more numerous than neurons
33
glial cells:
occupy the same total space as do neurons
34
which function is NOT performed by glia
transmitting information
35
one type of glia helps synchronize the activity of axons. they are called
astrocytes
36
which of the following is not true of astrocytes
they make up myelin sheaths in the periphery of the body
37
which type of glia remove waste material in the nervous system
astrocytes
38
what type of glial cells myelinate axons in the brain and spinal cord
oligodendrocytes
39
which type of glia release chemicals that modify the activity of neighboring neurons
astrocytes
40
what type of glia builds myelin sheath around axons in the periphery of the body
schwann cells
41
__ in the brain and spinal cord and ___ in the periphery are specialized types of glia that build the myelin sheaths that surround neurons
oligodendrocytes; schwann cells
42
glial cells whose function most closely resembles that of the immune system are called
microglia
43
radial glia:
guide the migration of neurons during embryonic development
44
of the following the most important consideration in developing a drug that will act in the brain is
if the drug will cross the blood brain barrier
45
the risk of having part of the brain unprotected by the blood brain barrier is
viruses or toxic chemicals that are most likely to damage it
46
in the brain, an arrangement of endothelial cells
does not allow most molecules to pass bc the cells are so tightly packed
47
what happens to viruses that manage to cross the bbb and enter the brain
stay in the nervous system throughout persons life
48
which would be most likely to cross bbb
small, uncharged molecules that can dissolve in the fats of the capillary walls
49
major disadvantage of bbb
certain required chemicals must be actively transported
50
compared to passive transport, major disadvantage of active transport is
requires expenditure of energy
51
two requirements for brain to metabolize glucose
thiamine and oxygen
52
why does the brain need thiamine
enable it to metabolize glucose
53
who is most likely to suffer from a thiamine deficiency
alcoholics (korsakoffs syndrome)
54
korsakoffs syndrome
is marked by severe memory impairments
55
the membrane of a neuron is specialized to
control the exchange of chemicals between the inside and outside of the cell
56
the membrane of a neuron is composed of __ with __ embedded in them
fat molecules, proteins
57
what is the difference in voltage called that typically exists between the inside and the outside of a neuron
resting potential
58
resting potential is mainly the result of
negatively charged proteins inside the cell
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resting potential of the inside of a neuron's membrane
-70 millivolts
60
the selectivity of a neuron membrane is analogous to?
blood brain barrier
61
allowing only certain people to cross the street and at only certain times is comparable to a neuron's
selective permeability
62
when a neuron's membrane is at rest, which of the following molecules crosses through it most slowly
potassium
63
when the neuronal membrane is at rest the sodium channels
are closed
64
when a neurons membrane is at rest, the concentration gradient tends to move sodium __ the cell and the electrical gradient tends to move it __ the cell
into; into
65
^potassium?
out of; into
66
the sodium-potassium pump, repeatedly transports __ sodium ions out of the cell while drawing __ potassium ions into it
three; two
67
electrical gradients lead to what kind of movements?
the movement of ions to areas having the opposite electrical charges
68
under which conditions would the sodium-potassium pump be far less effective in creating a concentration gradient?
if selective permeability of the membrane did not exist
69
the net effect of each cycle of the sodium potassium pump is to
decrease the number of positively charged ions within the cell
70
one major cause for the resting potential of a neuron's membrane?
sodium potassium pump
71
sodium potassium pump pumps sodium __ and potassium __
out; in
72
concentration gradients lead to what kinds of movement?
movement of ions to areas of their lowest concentrations
73
which of the following events would increase the concentration gradient of sodium
increased activity of the sodium potassium pump
74
concentration gradient for potassium tends to
push potassium out of the cell
75
when the neuron is at rest, what is responsible for moving potassium ions out of the cell
concentration gradient
76
when the neuron is at rest what is responsible for moving potassium ions into the cell
both sodium potassium pump and electrical gradients
77
when membrane is at rest what attracts potassium ions inside the cell
electrical gradient
78
when neuron is at rest what attracts sodium ions outside of the cell
sodium potassium pump
79
which of the following is an advantage of having a resting potential
cell is prepared to respond quickly to a stimulus
80
stimulation of a neuron takes place
at the synapse
81
result if a stimulus shifts the potential inside a neuron from the resting potential to a more negative potential
hyperpolarization
82
which of the following would produce hyperpolarization of a neuron
applying a negative charge inside the neuron with a microelectrode
83
result if a stimulus shifts the potential inside a neuron from the resting potential to a potential slightly closer to zero
depolarization
84
neuron will only produce an action potential only if the depolarization exceeds what level
the threshold of excitation
85
at what point do sodium gates start to allow sodium into the neuron
in response to any depolarization
86
if depolarization is less than a cells threshold
sodium crosses the membrane only slightly more than usual
87
which of the following would depolarize a neuron
increasing membrane permeability to sodium
88
the action potential of a neuron depends mostly on what movement of ions
sodium ions entering the cell
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in the normal course of an action potential
sodium remains much more concentrated outside than inside a neuron
90
voltage-activated channels are channels for which a change in the voltage across the membrane alters their
permeability
91
at the peak of the action potential, the electrical gradient of potassium
pushes potassium out of the cell
92
when the potential across a membrane reaches threshold, the sodium channels
open to let sodium enter rapidly
93
just after the peak of the ap what movement of ions restores the membrane to approximately the resting potential
potassium ions leave the cell
94
a drug that decreases the flow of potassium through the potassium gates of the membrane would:
slow the rate of the membrane to its resting potential
95
local anesthetic drugs such as novocain
block sodium gates
96
all or none law for axons
size of the AP is independent of the strength of the stimulus that initiated it, neuron produces an ap of maximal strength, or none at all
97
presence of all or non law suggests that neurons can only convey different messages by changing their
rate or pattern of action potentials
98
primary feature of a neuron that prevents the ap from traveling back from where it just passed is the
refractory period
99
during the relative refractory period
sodium gates are reverting to their usual state
100
where do most ap begin
axon hillock
101
what happens once an ap starts
regenerated to other points along the axon
102
what will affect the speed of an ap
resistance of the membrane
103
what will not affect the speed of an ap
length of the axon
104
how is the speed of an ap down an unmyelinated axon best described
faster in thick axons than in thin ones
105
presence of myelin and diameter of axon
affect the speed of an ap
106
increase of myelin sheath is to
increase velocity of transmission along an axon
107
if you were to stub your toe and feel the pressure a second or two before you feel the pain then which of the following is probably true
pressure sensitive neurons are large and myelinated
108
in a myelinated axon, where are sodium gates abundant
nodes of ranvier
109
to what does saltatory conduction refer?
transmission of an impulse along a myelinated axon
110
saltatory conduction__ the velocity of ap and __ the amount of energy used by the neuron
increases; decreases
111
what disease is related to the destruction of myelin sheaths
MS
112
which of the following is not governed by all or none law
local neurons
113
in what direction does a local neuron transmit information
equally well in any direction
114
which of the following describes the transmission of information in a local neuron
signal decreases in strength as it travels
115
why are local neurons more difficult to study
they are so small
