Chapter 11 Flashcards
1
Q
What are the functions of the nervous system?
A
- sensory input
- Integration
- Motor output
2
Q
What is the organization of the nervous system?
A
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
3
Q
The CNS contains the
A
Brain and spinal cord
4
Q
The PNS contains the
A
Paired spinal and cranial nerves
5
Q
The PNS has two functional divisions, what are they?
A
Sensory (afferent) division
Motor (efferent) division
6
Q
What fibers are in the sensory division?
A
Sensory afferent (Somatic afferent) fibers Visceral afferent fibers
7
Q
Sensory afferent fibers carry
A
Impulses from the skin, skeletal muscles, and joints to the brain (CNS)
8
Q
Visceral afferent fibers transmit
A
Impulses from visceral organs to the brain (CNS)
9
Q
The motor division transmits
A
Impulses from the CNS to effector organs, muscles, and glands
10
Q
What are the two main parts of the motor division?
A
Somatic and autonomic
11
Q
Is the somatic nervous system voluntary or involuntary?
A
Voluntary
12
Q
Is the autonomic nervous system voluntary or involuntary?
A
Involuntary
13
Q
The autonomic nervous system regulates
A
Smooth muscle and cardiac muscle
14
Q
What are the divisions of the autonomic nervous system?
A
Sympathetic and Parasympathetic
15
Q
The two principal cell types of the nervous system are
A
Neurons and supporting cells
16
Q
Supporting cells are
A
Cells that surround and wrap neurons
17
Q
Nerugoglia (glia cells) are ______ cells that
A
Supporting cells that
Provide a supportive scaffolding for neurons
18
Q
What are the most abundant, versatile, and highly branched glial cells?
A
Astrocytes (in CNS)
19
Q
Astrocytes in CNS cling to
A
Neurons and their synaptic endings
20
Q
Astrocytes in CNS cover
A
Capillaries
21
Q
Astrocytes in CNS are the barrier between what?
A
Neurons and capillaries
22
Q
What are small, ovoid cells with spiny processes?
A
Microglia in CNS
23
Q
Microglia in CNS are phagocytes that
A
Monitor the health of neurons
24
Q
Microglia in CNS are a type of (1) that (2)
A
(1) Macrophage
(2) Engulfs foreign particles
25
Ependymal cells in CNS range in shape from
Squamous to columnar
26
Ependymal cells in CNS line the
Cavities of the CNS (brain and spinal cord)
27
In ependymal cells in CNS, cilia circulate
Cerebrospinal fluid
28
Oligodendrocytes in CNS are (1) that (2)
(1) Branched cells
| (2) Wrap CNS nerve fibers
29
What forms the myelin sheaths?
Oligodendrocytes in CNS and Shwann cells
30
Shwann cells surround
Fibers of the PNS
31
Schwann cells are involved in
Regeneration in the PNS
32
Schwann cells form the
Tube and encourage axon growth
33
Satellite cells surround
Neuron cell bodies with ganglia in the PNS
34
Nerve cells are
Neurons
35
Neurons are composed of
A body, axon, and dendrites
36
Amitotic is the
Simple division of nucleus with replication of chromosomes
37
Are neurons mitotic or amitotic?
Amitotic
38
The plasma membrane of neurons function in
Electrical signaling
39
The nerve cell body is called
Perikaryon or Soma
40
The nerve cell body contains
The nucleus and a nuceolus
41
The nerve cell body is the major
Biosynthetic Center
42
The nerve cell body is the focal point for the
Outgrowth of neuronal processes
43
The nerve cell body has no (1) hence its (2) nature
(1) No centrioles (2) Amitotic nature
44
An Axon hillock is a
Cone-shaped area from which axons arise
45
The cluster of cell bodies in the CNS are
Nuclei
46
The cluster of cell bodies in the PNS are
Ganglia
47
Processes are
Arm-like extensions from the soma (body)
48
Processes are called what in the PNS and CNS?
PNS - Nerves
| CNS - Tracts
49
What are the two types of processes?
Axons and dendrites
50
Dendrites of motor neurons are short or long?
Short
51
Dendrites of motor neurons are what kind of processes?
Diffusely branched processes
52
Dendrites of motor neurons are the _______ regions of the neuron
Receptive or input
53
Dendrites of motor neurons create enormous
Surface area for receptions of signal from other neurons
54
Dendrites of motor neurons conduct impulse
Toward cell body
55
Axons arise from
The hillock
56
Axons are fat or thin?
Thin
57
T/F Axons can be short or very long
True
58
Long axons are called
Nerve fibers
59
How many unbranched axon per neuron?
Usually only one
60
Larger diameter of axons cause
Faster conduction
61
What are the functions of axons?
1. Generate and transmit ACTION POTENTIALS
2. Carries IMPULSES AWAY from cell body
3. Secrete NEUROTRANSMITTERS from axonal terminals
62
Myelin sheath is the
Whitish, fatty, segmented sheath around most long axons
63
The myelin sheath functions are
1. PROTECT the axon
2. Electrically INSULATE fibers from one another
3. INCREASE THE SPEED of nerve impulse transmission
64
Nodes of Ranvier are
Gaps in the myelin sheath between adjacent Shwann cells
65
Nodes of Ranvier are the sites where
Axon collaterals can emerge
66
In axons of the CNS both
Myelinated and unmyelinated fibers are present
67
In axons of the CNS myelin sheaths are formed by
Oligodendrocytes
68
The regions of the brain and spinal cord are
White matter and gray matter
69
White matter is a
Dense collection of myelinated fibers
70
White matter have (1) in regions of (2)
(1) Myelinated fibers
| (2) Brain and spinal cord
71
Where is gray matter found?
Mostly in the Soma (nerve cell body)
72
T/F Gray matter is myelinated
False; Unmyelinated
73
What are the types of neuron classification?
Structural and Functional
74
Structural neuron classification is divided into
Multipolar
Bipolar
Unipolar
75
Functional neuron classification is divided into
Sensory (afferent)
Motor (efferent)
Interneurons (association neurons)
76
Action potentials are also known as
Nerve Impulses
77
Action potentials are
Electrical impulses carried along the length of axons
78
Action potentials are always (1) regardless of (2)
(1) The same
| (2) Stimulus
79
What is the underlying functional feature of the nervous system?
Action Potentials
80
Voltage is the
Measure of potential energy generated by separated charges
81
There is a potential on either side of membranes when
1. The # of ions is different across the membrane
| 2. The membrane provides a resistance to ion flow
82
Types of plasma membrane ion channels
1. Passive/Leakage channels
2. Chemically gated channels
3. Voltage-gated channels
4. Mechanically gated channels
83
Chemically gated channels open with
Binding of a specific neurotransmitter
84
Voltage-gated channels open and close
In response to membrane potential
85
A chemically gated channel is closed when
A neurotransmitter is not bound to the extracellular receptor
86
A chemically gated channel is open when
A neurotransmitter is attached to the receptor
87
Example of a chemically gated channel is
Na+ -K gated channel
88
In a Na+ -K gated channel, when it is closed (1) and when it is open (2)
(1) Na+ cannot enter the cell and K+ cannot exit the cell
| (2) Na+ enters the cell and K+ exits the cell
89
A voltage-gated channel is closed when
The intracellular environment is negative
90
A voltage-gated channel is open when
The intracellular environment is positive
91
An example of a voltage-gated channel is
Na+ channel
92
In a Na+ channel, when it is closed (1) and when it is open (2)
(1) Na+ cannot enter the cell
| (2) Na+ can enter the cell
93
Resting Membrane Potential is the
Potential difference (-70 mV) across the membrane of a resting neuron
94
Voltage across the membrane is
-70 mV
95
Resting Membrane Potential is more
Negative on the inside
96
The resting membrane potential is established by
Na/K pump
97
The resting membrane potential is generated by
Different concentrations of Na+, K+, Cl- and proteins anions (A-)
98
Ionic differences are the consequences of
1. Differential permeability of the neurilemma to Na+ and K+
| 2. Operation of the sodium-potassium pump
99
Membrane potentials are used to
Integrate, send, and receive information
100
Membrane potential changes are produced by
1. Changes in membrane permeability to ions
| 2. Alterations of ion concentrations across the membrane
101
Changes in membrane potential are caused by
1. Depolarization
2. Repolarization
3. Hyperpolarization
102
In depolarization the inside of the membrane
Becomes less negative
103
In repolarization the membrane
Returns to it's resting membrane potential
104
In hyperpolarization the inside of the membrane
Becomes more negative than the resting potential
105
Graded potentials are short lived or long lived?
Short lived
106
Graded potentials decrease
In intensity with distance
107
With graded potentials, magnitude
Varies directly with the strength of the stimulus
108
Sufficiently strong graded potentials can
Initiate action potentials
109
In graded potentials, voltage changes
Are decremental (or gradually decreasing)
110
In graded potentials, the current is
Quickly dissipated
111
Why is the current quickly dissipated in graded potentials?
Due to the leaky plasma membrane
112
Graded potentials only travel
Over short distances
113
Action potential is a
Brief reversal of membrane potential with a total amplitude (change in voltage) of 100 mV
114
Action potentials are only generated
By muscle cells and neurons
115
T/F Action potentials decrease in strength over distance
False, they do not decrease
116
When an action potential is in resting state Na+ and K+ channels
Are closed
117
What accounts for small movements of Na+ and K+ when an action potential is in resting state?
Leakage
118
When an action potential is in resting state, each Na+ channel
Has two voltage-regulated gates
119
What are the two Na+ voltage-regulated gates?
Activation gates
| Inactivation gates
120
Are activation gates open or closed in resting state?
Closed
121
Are inactivation gates open or closed in resting state?
Open
122
When an action potential is in depolarization phase, Na+ permeability (1); membrane potential (2)
(1) Increases
| (2) Reverses
123
When an action potential is in depolarization phase, Na+ (activation) gates are (1); K+ gates are (2)
(1) Opened
| (2) Closed
124
Threshold is
A critical level of depolarization (-55 to -50 mV)
125
When an action potential is in repolarization phase, Na+ inactivation gates
Close
126
When an action potential is in depolarization phase, membrane permeability to Na+
Declines to resting levels
127
When an action potential is in depolarization phase, when Na+ gates close,
Voltage-sensitive K+ gates open
128
When an action potential is in depolarization phase, K+ (1) and internal negativity of (2) is (3)
(1) Exits the cell
(2) The resting neuron
(3) Restored
129
When an action potential is in Hyperpolarization phase, K+ gates
Remain open
130
When the K+ gates remain open during hyperpolarization phase, this causes
An excessive efflux (flowing out) of K+
131
What causes hyperpolarization of the membrane?
The efflux of K+
132
When an action potential is in hyperpolarization phase, the neuron is insensitive to
Stimulus and depolarization
133
Repolarization restores
The resting electrical conditions of the neuron
134
Repolarization does not restore
The resting ionic conditions
135
After repolarization, the Na+ - K+ pump
Redistributes the ion back to resting conditions
136
What are the phases of the action potential?
1. Resting state
2. Depolarization phase
3. Repolarization phase
4. Hyperpolarization phase
137
Threshold is typically reached when
The membrane is depolarized by 15 - 20 mV
138
The threshold is established by
The total amount of current flowing through the membrane
139
Are weak (subthreshold) stimuli or strong (threshold) stimuli relayed into action potentials?
Strong stimuli are relayed into action potentials
140
The all-or-none phenomenon says that
Action potentials either happen completely or not at all
141
The absolute refractory period is the
Time from the opening of the Na+ activation gates until the closing of inactivation gates
142
The absolute refractory period prevents the neuron from
Generating an action potential
143
The absolute refractory period ensures that each action potential
Is Separate
144
The absolute refractory period enforces
One-way transmission of nerve impulses
145
The relative refractory period is
The interval following the absolute refractory period
146
What are the position of the Na+ and K+ gates during the relative refractory period?
Na+ gates are closed
| K+ gates are open
147
What is occuring during the relative refractory period?
Repolarization
148
During the relative refractory period, the threshold level is
Elevated
149
An elevated threshold level during the relative refractory period allows
Strong stimuli to increase the frequency of action potential events
150
Rate of impulse propagation is determined by
1. Axon diameter
| 2. Presence of a myelin sheath
151
A current can pass through a myelin sheath
ONLY at the nodes of Ranvier (myelin sheath gaps)
152
Action potentials are triggered (1) and (2)
(1) ONLY at the nodes
| (2) Jump from one node to the next
153
Multiple sclerosis is
An autoimmune disease that mainly affects young adults
154
In MS the immune system
Attacks myelin proteins
155
In MS the axons
Are not damaged
156
The symptoms of MS are
Visual disturbances
Weakness
Loss of muscular control
Urinary incontinence
157
In MS the nerve fibers (1) and myelin sheaths in the CNS become (2)
(1) Are severed
| (2) Nonfunctional scleroses
158
Nonfunctional scleroses is when
Sheaths are reduced to hard lesions
159
A synapse is
A junction that mediates information transfer from one neuron to
a) another neuron
b) an effector cell
160
A presynaptic neuron conducts
Impulses toward the synapse
161
A postsynaptic neuron transmits
Impulses away from the synapse
162
What are the two types of postsynaptic potentials?
(1) EPSP - Excitatory postsynaptic potentials
| (2) IPSP - Inhibitory postsynaptic potentials
163
EPSPs are
Graded potentials that can initiate an action potential in an axon
164
EPSPS use only
Chemically gated channels
165
Postsynaptic membranes do not
Generate action potentials
166
Only ____ generate action potentials
Axons
167
The strength of an EPSP depends on
The amount of neurotransmitter bound to receptors
168
If EPSPs reach the axon hillock,
Action potential occurs down the axon
169
Can a single EPSP induce an action potential?
No
170
EPSPs must (1) to (2)
(1) Summate temporally or spatially
| (2) Induce an action potential
171
Temporal summation occurs when
Presynaptic neurons transmit impulses in rapid-fire order
172
Spatial summation occurs when
The postsynaptic neuron is stimulated by a large number of terminals at the same time
173
IPSPs can also summate
With EPSPs
174
When IPSPs summate with EPSPs,
They cancel each other
175
Neurotransmitters are
Chemicals used for neuronal communication with the body and the brain
176
T/F Only a handful of neurotransmitters have been identified
False, 50 different neurotransmitters have been identified
177
How are neurotransmitters classified?
Chemically and functionally
178
GABA stands for
Gamma - aminobutyric acid
179
GABA is the most
Prevalent neurotransmitter in the brain
180
Is GABA excitatory or inhibitory?
Inhibitory
181
Huntington's is the
Lack of CABA releasing neurons
182
Norepinephrine is a neurotransmitter that
Makes a person feel good
183
Norepinephrine reuptake is
Blocked by cocaine
184
Dopamine is a neurotrasmitter that
Makes a person feel good
185
Dopamine plays a part in
The regulation of skeletal muscle
186
Dopamine is deficient in
Parkinson's disease
187
Serotonin is a neurotransmitter that
Regulates mood
188
Serotonin is excitatory or inhibitory?
Inhibitory
189
Serotonin reuptake is
Blocked by Prozac
190
Endorphins are neurotransmitters that
Inhibit pain
191
Effects of endorphins are mimicked by
Morphine and heroin
192
Acetylcholine was the
First neurotransmitter identified
193
Acetylcholine is the best
Understood neurotransmitter
194
Acetylcholine is released
At the neuromuscular junction
195
Acetylcholine is synthesized and enclosed in
Synaptic vesicles
196
Acetylcholine is degraded by
The enzyme acteylcholinesterase (AChE)
197
Acetylecholine is released by
1. All neurons that stimulate skeletal muscle
| 2. Some neurons in the autonomic nervous system
198
The functional classification of neurotransmitters is divided into
Excitatory and inhibitory
199
Excitatory neurotransmitters cause
Depolarizations
200
Inhibitory neurotransmitters cause
Hyperpolarizations
201
T/F Some neurotransmitters have both excitatory and inhibitory effects
True
