ch. 12. nervous system cell - study guide Flashcards
2
Q
Consists of the brain and spinal cord
A
central nervous system
3
Q
Composed of nerves arising from the brain and spinal cord
A
peripheral nervous system
4
Q
PNS subdivision that transmits incoming information from the sensory organs to the CNS
A
afferent division
5
Q
produces the “fight or flight” response
A
sympathetic division
6
Q
subdivision that carries infromation from the CNS to skeletal muscle
A
somatic nervous system
7
Q
subdivision of efferent divsion that transmits information to smooth muscle, cardiac muscle, and glands
A
autonomic nervous system
8
Q
consists of all outgoing motor pathways
A
efferent nervous system
9
Q
coordinates the body’s normal resting activities
A
parasympathetic nervous system
10
Q
has the ability of phagocytosis
A
microglia
11
Q
helps to form the blood-brain barrier
A
astrocyte
12
Q
produces fatty myelin sheath in the PNS
A
schwann cell
13
Q
largest and most numerous of the neuroglia that forms the neurilemma
A
astrocyte
14
Q
produces myelin sheath in the CNS
A
oligodendrocyte
15
Q
type of neuroglia that forms the neurilemma
A
schwann cell
16
Q
“star-cell”
A
astrocyte
17
Q
disorder of this cell associated with multiple sclerosis
A
oligodendrocyte
18
Q
Which of the following is/are classified as nerve fibers?a) axonb) dendritesc) both a and bd) none of the above
A
c
19
Q
Which of the following conduct impulses toward the cell body?a) axonsb) dendritesc) Nissl bodiesd) none of the above
A
b
20
Q
A neuron with one axon and several dendrites is a:a) multipolar neuronb) unipolar neuronc) bipolar neurond) none of the above
A
a
21
Q
Which type of neuron lies entirely within the CNSa) afferentb) efferentc) interneurond) none of the above
A
c
22
Q
Which sequence best represents the course of an impulse over a reflex arc?a) receptor, synapse, sensory neuron, motor neuron, effectorb) effector, sensory neuron, synapse, motor neuron, receptorc) receptor, motor neuron, synapse, sensory neuron, effectord) receptor, sensory neuron, interneuron, motor neuron, effector
A
d
23
Q
A complete nerve, consisting of numerous fascicles and their blood supply, is held together by a fibrous coat called the:a) endoneuriumb) perineuriumc) epineuriumd) fascicles
A
c
24
Q
Small, distinct regions of gray matter within the CNS are usually called:a) white matterb) nucleic) gangliad) fascicles
A
b
25
Q
Nerves that contain mostly efferent fibers are called:a) sensory nervesb) motor nervesc) mixed nervesd) Schwann nerves
A
b
26
Gray matter in the CNS consists ofa) nerve fibersb) neurogliac) axonsd) cell bodies
d
27
Most nerves in the human nervous system are:a) sensory nervesb) motor nervesc) mixed nervesd) reflex nerves
c
28
True or false? Evidence now indicates that neurons may be replaced.
t
29
True or false? Regeneration of nerve fibers will occur if the cell body is intact and the fibers have a neurilemma.
t
30
True or false? There are no differences between the CNS and PNS concerning the repair of damaged fibers.
f
31
Compared to the inside of the cell, the outside of most cell membranes is:a) positiveb) negativec) equald) none of the above
a
32
The difference in electrical charge across a plasma membrane is called:a) depolarizationb) membrane potentialc) both a and bd) none of the above
b
33
A neuron's resting membrane potential is:a) 70 mVb) -70 mVc) 30 mVd) -30 mV
b
34
Which of the following statements is true concerning the sodium-potassium pump?a) 3 sodium ions are pumped out of the neuron for every 2 potassium ions into the neuronb) 2 sodium ions are pumped out of the neuron for every 3 potassium ions pumped into the neuronc) 3 sodium ions are pumped out of the neuron for every 3 chloride ions pumped into the neurond) 3 sodium ions are pumped out of the neuron for every 3 potassium ions pumped into the neuron
a
35
True or false? A membrane that exhibits a membrane potential is said to be polarized.
t
36
True or false? A slight shift away from the resting membrane potential is a specific region of the plasma membrane often called a stimulus-gated channel
f
37
True or false? Chlorine ions (Cl-) are the dominant extracellular cations.
f
38
During a relative refractory period:a) an action potential is impossibleb) an action potential is possible only in response to a very strong stimulic) an action potential is occurringd) none of the above
b
39
Voltage-gated channels are:a) membrane channels that close during voltage fluctuationsb) membrane channels that open in response to voltage fluctuationsc) membrane channels that are altered from an extremely high stimulusd) none of the above
b
40
When current leaps across an insulating myelin sheath from node of Ranvier to node of Ranvier, the type of impulse conduction is:a) repolarizationb) refractionc) saltatory conductiond) diffusion
c
41
The larger the diameter of a nerve fibera) the slower the speed of conductionb) the faster the speed of conductionc) fiber diameter does not influence speed of conductiond) the more the speed fluctuates
b
42
True or false? Action potential and nerve impulse are synonymous
t
43
True or false? When repolarization has occurred, an impuls cannot be conducted
f
44
True or false? The action potential is an all-or-none response
t
45
True or false? Many anesthetics function by inhibiting the opening of sodium channels and thus blocking the initiation and conduction of nerve impulses.
t
46
Which of the following structures is not a main component of a chemical synapse?a) synaptic knobb) synaptic cleftc) synaptic processd) plasma membrane of postsynaptic neuron
c
47
A synaptic knob is located on the:a) synaptic cleftb) axonc) dendrited) cell body
b
48
Which of the following is true of spatial summation?a) neurotransmitters released simultaneously from several presynaptic knobs coverage on one postsynaptic neuronb) simultaneous stimulation of more than one postsynaptic neuron occursc) impulses are fired in a rapid succession by the same neurond) speed of impulse transmission is increased when several neurotransmitters are released
a
49
True or false? In an adult, the nervous system is replete with both electrical synapses and chemical synapses
f
50
True or false? Rapid-succession stimulation of a postsynaptic neuron by a synaptic knob can have a cumulative effect over time that can result in an action potential
t
51
Ca++ ions cause the release of neurotransmitters across the synaptic cleft.
t
52
Neurotransmitters are released in a synapse and bind to:a) presynaptic terminalsb) the synaptic cleftc) the base of the axond) receptors on the postsynaptic terminal
d
53
The main chemical classes of neurotransmitters include all of the following except:a) acetylcholineb) norepinephrinec) amino acidsd) amines
b
54
Which of the following is not an example of an amine neurotransmitter?a) serotoninb) histaminec) glycined) dopamine
c
55
Severe depression can be caused by a deficit in which of the following neurotransmitters?a) acetylcholineb) amino acidsc) aminesd) neuropeptides
c
56
Which of the following is not a catecholamine?a) epinephrineb) norepinephrinec) dopamined) serotonin
d
57
True or false? Many biologist now believe that neuropeptides are the most common neurotransmitters in the CNS
f
58
True or false? Cocaine produces a temporary feeling of well-being by blocking the uptake of dopamine
t
59
________ ___________ is a disorder of the nervous system that involves the glia, rather than neurons
multiple sclerosis
60
Most disorders of the nervous system cells involve __________ rather than neurons.
glia
61
A synaptic knob is a tiny bulge at the end of the (presynaptic or postsynaptic) neuron's axon.
presynaptic
62
Acetylcholine is an example of a (neurotransmitter or protein molecule receptor)
neurotransmitter
63
Neurotransmitters are chemicals that allow neurons to (communicate or reproduce) with one another.
communicate
64
Neurotransmitters are distributed (randomly or specifically) into groups of neurons.
specifically
65
Endorphins and enkephalins are neurotransmitters that inhibit conduction of (fear or pain)
pain
66
Unipolar neurons are always (sensory or motor) neurons
sensory
67
In the peripheral nervous system, small regions of gray matter are known as (nuclei or ganglia)
ganglia
68
The distal tips of axons form branches called (telodendria or axon hillock)
telodendria
69
neurons or neuroglia?axon
neurons
70
neurons or neuroglia?supporting cells
neuroglia
71
neurons or neuroglia?astrocytes
neuroglia
72
neurons or neuroglia?sensory
neurons
73
neurons or neuroglia?conduct impulses
neurons
74
neurons or neuroglia?form the myelin sheath around central nerve fibers
neuroglia
75
neurons or neuroglia?phagocytosis
neuroglia
76
neurons or neuroglia?efferent
neurons
77
neurons or neuroglia?multiple sclerosis
neuroglia
78
neurons or neuroglia?multipolar
neurons
79
List the major subdivisions of the human nervous system
Central and peripheral.
80
What 2 organs make up the central nervous system
Brain and spinal cord.
81
Contrast the somatic nervous system with the autonomic nervous system.
Some pathways of the somatic nervous system carry information to the somatic effectors, which are the skeletal muscles. Pathways of the autonomic nervous system carry information to the visceral effectors, which are the smooth muscles, cardiac muscles, and glands.
82
What are the 5 main types of glia
astrocytesmicrogliaependymal cellsoligondendrocytesSchwann cells.
83
Describe the myelin sheath found on some nerve fibers
The myelin sheath is formed by layers of Schwann cell membrane containing the white, fatty substance called myelin. It is important in the proper conduction of impulses along the nerve fiber.
84
What is a neurilemma
The neurilemma is a nerve sheath formed as each Schwann cell wraps around the nerve fiber, and its nucleus and cytoplasm are squeezed to the perimeter.
85
Describe the 3 different forms of Schwann cells
Myelinated fibers (white fibers): nerve fibers with many Schwann cells forming a thick myelinated sheath. Unmyelinated fibers (gray fibers): nerve fibers held together by a single Schwann cell that does not wrap around them to form a thick myelin sheath. Satellite cell: a special Schwann cell that surrounds the cell body of a neuron.
86
Compare and contrast axons and dendrites
Both axons and dendrites are threadlike extensions from the neuron’s cell body. However, dendrites usually branch extensively from the body, and they receive stimuli and conduct electrical signals toward the cell body and/or axon. The distal ends may be called receptors, and some in the brain have small knoblike dendritic spines. Axons are a single process from the cell body that conduct impulses away from the cell body. The distal tips form branches called telodendria that terminate in synaptic knobs.
87
List the 3 types of of structural classification and the 3 types of functional classification in neurons
Structural: multipolar, bipolar, unipolar. Functional: afferent neurons, efferent neurons, interneurons.
88
What are the 3 layers of connective tissues that hold the fibers of a nerve together?
Endoneurium, perineurium, and epineurium.
89
What is the difference between a nerve and a tract?
Nerves are bundles of peripheral nerve fibers held together by several layers of connective tissues. Bundles of nerve fibers are called tracts.
90
How does white matter differ from gray matter?
White matter is made up of myelinated fibers. Cell bodies and unmyelinated fibers make up the gray matter.
91
Under what circumstances can a nerve fiber be repaired?
Nerve fibers can sometimes be repaired if damage is not extensive, when the cell body and neurilemma remain intact and scarring has not occurred.
92
What mechanisms are involved in producing the resting membrane potential
The mechanisms that produce and maintain the resting membrane potential do so by promoting a slight ionic imbalance across the neuron’s plasma membrane. These mechanisms produce a slight excess of positive ions on its outer surface. Included among these mechanisms are gated channels and the sodium-potassium pump.
93
In a resting neuron, what positive ion is most abundant outside the plasma membrane?
Sodium is more abundant outside
94
What positive ion is most abundant inside the plasma membrane
potassium is more abundant inside.
95
How does depolarization of a membrane differ from hyperpolarization
During depolarization the excess of positive ions outside the plasma membrane decreases and the magnitude of the membrane potential is reduced toward zero. Movement of the membrane potential away from zero (thus below the usual RMP) is called hyperpolarization.
96
List the events that lead to the initiation of an action potential
(1) A stimulus triggers stimulus-gated Na+ channels to open and allow inward Na+ diffusion. (2) As the threshold potential is reached, voltage-gated Na+ channels open. (3) As more Na+ enters the cell through voltage-gated sodium channels, the membrane depolarizes even further. (4) The magnitude of the action potential peaks (at + 30mV) when voltage-gated Na+ channels close. (5) Repolarization begins when voltage-gated K+ channels open, allowing outward diffusion of K+. (6) After a brief period of hyperpolarization, the resting potential is restored by the sodium-potassium pump and the return of ion channels to their resting state.
97
What is meant by the term threshold potential
The threshold potential occurs when the magnitude of the local depolarization surpasses a limit (typically -59 mV).
98
How does impulse conduction in an unmyelinated fiber differ from impulse conduction in a myelinated fiber?
Myelinated fibers conduct impulses faster than unmyelinated fibers.
99
What are the 3 structural components of a synapse?
Synaptic knob, synaptic cleft, and the plasma membrane of the postsynaptic neuron.
100
List the steps of synaptic transmission:
(1) When an action potential reaches a synaptic knob, voltage-gated calcium channels in its membrane open and allow calcium ions to diffuse into the knob rapidly. (2) The increase in intracellular Ca++ concentration triggers the movement of neurotransmitter vesicles to the plasma membrane of the synaptic knob. (3) The released neurotransmitter molecules almost instantaneously diffuse across the narrow synaptic cleft and contact the postsynaptic neuron’s plasma membrane. Here they bind to receptor molecules that trigger the gated channels to open. (4) The opening of the ion channels in the postsynaptic membrane may produce a local potential called a postsynaptic potential. Excitatory neurotransmitters cause both Na+ and K+ channels to open, causing a temporary depolarization called an excitatory postsynaptic potential. Inhibitory neurotransmitters cause K+ channels and/or Cl- channels to open. If K+ channels open, K+ rushes outward; if Cl- channels open, Cl- rushes inward. Either event makes the inside of the membrane even more negative than at the resting potential (inhibitory postsynaptic potential). (5) Once a transmitter binds to its postsynaptic receptors, its action is quickly terminated.
101
What is an EPSP? What is an IPSP?
EPSP: excitatory postsynaptic potential. IPSP: inhibitory postsynaptic potential.
102
How does temporal summation differ from spatial summation
Spatial summation is when the sum of the local potential reaches the threshold potential, causing voltage-gated channels in the axon membrane to open, thus producing an action potential. Temporal summation is when synaptic knobs stimulate a postsynaptic neuron in rapid succession, and their effects can add up over a brief period of time to produce an action potential.
103
How are memories formed?
The most widely held idea on how memories are formed is that information is stored in the form of an increased flow of information at synapses in particular pathways. Thus, memories form when the flow of information is facilitated at synapses.
104
How do excitatory neurotransmitters differ from inhibitory neurotransmitters?
Excitatory neurotransmitters have an excitatory effect at synapses. Inhibitory neurotransmitters have an inhibitory effect at the synapses.
105
What are the 4 chemical classes of neurotransmitters?
Acetycholine, amines, amino acids, and other small molecules.
106
What are neuromodulators?
A neuromodulator is a “cotransmitter” that regulates or modulates the effects of the neurotransmitter(s) released along with it.
