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ANAPHY > Nervous system > Flashcards

Nervous system Flashcards

1
Q

two main subdivisions of NS

A

central nervous system and the peripheral nervous system

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2
Q

deals with normal functioning and disorders of the nervous system

A

Neurology

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3
Q

consists of the brain and spinal cord

A

CNS

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4
Q

Most signals that stimulate muscles to contract and glands to secrete originate in the

A

CNS

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5
Q

include nerves and sensory receptors

A

Peripheral NS

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6
Q

a bundle of hundreds to thousands of axons plus associated connective tissue and blood vessels that lies outside the brain and spinal cord

A

nerve

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7
Q

no. of pairs of cranial nerves

A

12

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8
Q

no. of pairs of spinal nerves

A

31

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9
Q

refers to a structure of the nervous system that monitors changes in the external or internal environment.

A

sensory receptor

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10
Q

The PNS is divided into

A

sensory and motor divisions

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11
Q

conveys input into the CNS from sensory receptors in the body.

A

sensory or afferent division of the PNS

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12
Q

This division provides the CNS with sensory information about the somatic senses and special senses

A

afferent division

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13
Q

tactile, thermal, pain, and proprioceptive sensations

A

somatic senses

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14
Q

smell, taste, vision, hearing, and equilibrium

A

special senses

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15
Q

conveys output from the CNS to effectors (muscles and glands)

A

motor or efferent division of the PNS

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16
Q

motor or efferent division of the PNS divisions

A

somatic nervous system and an autonomic nervous system

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17
Q

conveys output from the CNS to skeletal muscles only. Because its motor responses can be consciously controlled, the action of this part of the PNS is voluntary.

A

somatic NS

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18
Q

conveys output from the CNS to smooth muscle, cardiac muscle, and glands. Because its motor responses are not normally under conscious control, the action of this is involuntary

A

autonomic nervous system

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19
Q

The ANS is comprised of two main branches

A

the sympathetic division and the parasympathetic division

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20
Q

A third branch of the autonomic nervous system; an extensive network of over 100 million neurons confined to the wall of the digestive canal

A

enteric plexuses

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21
Q

helps regulate the activity of the smooth muscle and glands of the digestive canal; can function independently, they communicates with and are regulated by the other branches of the ANS.

A

enteric plexuses

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22
Q

three basic functions of NS

A

sensory (input), integrative (process), and motor (output)

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23
Q

The nervous system processes sensory information by analyzing it and making decisions for appropriate responses—an activity known as

A

integration

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24
Q

Nervous tissue comprises two types of cells

A

neurons and neuroglia

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25
Q

provide most of the unique functions of the nervous system, such as sensing, thinking, remembering, controlling muscle activity, and regulating glandular secretions

A

neurons

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26
Q

support, nourish, and protect neurons, and maintain the interstitial fluid that bathes them

A

neuroglia

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27
Q

the ability to respond to a stimulus and convert it into an action potential.

A

electrical excitability

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28
Q

is an electrical signal that propagates (travels) along the surface of the membrane of a neuron

A

nerve impulse (action potential)

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29
Q

Nerve impulses travel these great distances at speeds ranging from

A

0.5 to 130 meters per second (1 to 290 mi/hr)

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30
Q

Most neurons have three parts

A

(1) a cell body, (2) dendrites, and (3) an axon

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31
Q

contains a nucleus surrounded by cytoplasm that includes typical cellular organelles such as lysosomes, mitochondria, and a Golgi complex.

A

cell body

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32
Q

cell body is also known as

A

perikaryon or soma

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33
Q

Neuronal cell bodies also contain free ribosomes and prominent clusters of rough endoplasmic reticulum, termed

A

Nissl bodies

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34
Q

The cytoskeleton includes both

A

neurofibrils and microtubules

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35
Q

composed of bundles of intermediate filaments that provide the cell shape and support

A

neurofibrils

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36
Q

assist in moving materials between the cell
body and axon

A

microtubules

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37
Q

a pigment that occurs as clumps of yellowish-brown granules in the cytoplasm; a product of neuronal lysosomes that accumulates as the neuron ages, but does not seem to harm the neuron.

A

lipofuscin

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38
Q

These bumps are caused by many small projections of the plasma membrane, called ___; which are receptor sites that bind chemical messengers from other neurons

A

somatic spines

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39
Q

A collection of neuron cell bodies outside the CNS is called a

A

ganglion

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40
Q

is a general term for any neuronal process
(extension) that emerges from the cell body of a neuron

A

nerve fiber

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41
Q

neurons have two kinds of processes

A

multiple dendrites and a single axon

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42
Q

are the receiving or input portions of a neuron

A

Dendrites

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43
Q

Their cytoplasm contains Nissl bodies, mitochondria, and other organelles.

A

dendrites

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44
Q

propagates nerve impulses toward another neuron, a muscle fiber, or a gland cell

A

axon

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45
Q

An axon is a long, thin, cylindrical projection that often joins to the cell body at a cone shaped elevation called the

A

axon hillock

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46
Q

The part of the axon closest to the axon hillock is the

A

initial segment

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47
Q

In most neurons, nerve impulses arise at the junction of the axon hillock and the initial segment, an area called the _____from which they travel along the axon to their destination.

A

trigger zone

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48
Q

contains mitochondria, microtubules, and neurofibrils.

A

axon

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49
Q

it does not have RER

A

axon

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50
Q

The cytoplasm of an axon, called axoplasm, is surrounded by a plasma membrane known as the

A

axolemma

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51
Q

axon side branches

A

axon collaterals

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52
Q

The axon and its collaterals end by dividing into many fine processes called

A

axon terminals or axon telodendria

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53
Q

The site of communication between two neurons or between a neuron and an effector cell is called a

A

synapse

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54
Q

The tips of some axon terminals exhibit a string of swollen bumps called

A

Varicosities

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55
Q

is a molecule released from a synaptic vesicle
that excites or inhibits another neuron, muscle fiber, or gland cell.

A

neurotransmitter

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56
Q

two types of transport systems carry materials from the cell body to the axon terminals and back

A

slow and fast axonal transport

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57
Q

The slower system, which moves materials about 1–5 mm per day; t conveys axoplasm in one direction only

A

slow axonal transport

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58
Q

supplies new axoplasm to developing or regenerating axons and replenishes axoplasm in growing and mature axons.

A

slow axonal transport

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59
Q

which is capable of moving materials a distance of 200–400 mm per day, uses proteins that function as “motors” to move materials along the surfaces of microtubules of the neuron’s cytoskeleton

A

fast axonal transport

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60
Q

moves materials in both directions—away from and toward the cell body

A

fast axonal transport

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61
Q

moves organelles and synaptic vesicles from the cell body to the axon terminals

A

anterograde

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62
Q

moves membrane vesicles and other cellular materials from the axon terminals to the cell body to be degraded or recycled.

A

retrograde

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63
Q

substances include trophic chemicals such as nerve growth factor and harmful agents such as tetanus toxin and the viruses that cause rabies, herpes simplex, and polio travels in what direction

A

fast retrograde transport

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64
Q

usually have several dendrites and one axon

A

Multipolar neurons

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65
Q

Most neurons in the brain and spinal cord are of this type, as well as all motor neurons

A

Multipolar neurons

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66
Q

have one main dendrite and one axon

A

Bipolar neurons

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67
Q

found in the retina of the eye, the inner ear, and the olfactory area of the brain

A

Bipolar neurons

68
Q

have dendrites and one axon that are fused together to form a continuous process that emerges from the cell body

A

Pseudounipolar or unipolar neurons

69
Q

The trigger zone for nerve impulses in a unipolar neuron is at the

A

junction of the dendrites and axon

69
Q

The dendrites of most pseudounipolar neurons function as

A

sensory receptors

70
Q

neurons are named for the histologist who
first described them

A

Purkinje cells

71
Q

named based on their shape

A

pyramidal cells, found in the cerebral cortex of the brain

72
Q

Functional Classification of neurons

A

sensory, motor and interneurons

73
Q

Motor neurons structure

A

multipolar

74
Q

integrate (process) incoming sensory information from sensory neurons and then elicit a motor response by activating the appropriate motor neurons.

A

interneurons

75
Q

do not generate or propagate nerve impulses, and they can multiply and divide in the mature nervous system.

A

neuroglia

76
Q

Brain tumors derived from glia, called

A

gliomas

77
Q

four types of neuroglia found in the CNS

A

astrocytes, oligodendrocytes, microglia, and ependymal cells

78
Q

two types of neuroglia found in the PNS

A

Schwann cells and satellite cells

79
Q

Neuroglia of the CNS can be classified on the basis of

A

size, cytoplasmic processes, and intracellular organization

80
Q

These star-shaped cells have many processes and are the largest and most numerous of the neuroglia

A

astrocytes

81
Q

astrocytes that have many short branching processes and are found in gray matter

A

Protoplasmic astrocytes

82
Q

astrocytes have many long unbranched processes and are located mainly in white matter

A

Fibrous astrocytes

83
Q

The processes of astrocytes make contact with

A

blood capillaries, neurons, and the pia mater

84
Q

functional neurons of the PNS

A

sensory and motor neurons

85
Q

restricts the movement of substances between the blood and interstitial fluid of the CNS.

A

blood–brain barrier

86
Q

The functions of astrocytes include

A
  1. Astrocytes contain microfilaments that give them considerable strength, which enables them to support neurons
  2. Processes of astrocytes wrapped around blood capillaries isolate neurons of the CNS from various potentially harmful substances in blood by secreting chemicals that maintain the unique selective permeability characteristics of the endothelial cells of the capillaries
87
Q

In the embryo, they secrete chemicals that appear to regulate the growth, migration, and interconnection among neurons in the brain

A

astrocytes

88
Q

help to maintain the appropriate chemical environment for the generation of nerve impulses.

A

astrocytes

89
Q

serve as a conduit for the passage of nutrients and other substances between blood capillaries and neurons

A

astrocytes

90
Q

play a role in learning and memory by influencing the formation of neural synapses

A

astrocytes

91
Q

are responsible for forming and maintaining the myelin sheath around CNS axons

A

Oligodendrocytes

92
Q

is a multilayered lipid and protein covering around some axons that insulates them and increases the speed of nerve impulse conduction

A

myelin sheath

93
Q

These neuroglia are small cells with slender processes that give off numerous spinelike projections

A

microglia

94
Q

function as phagocytes; they remove cellular debris formed during normal development of the nervous system and phagocytize microbes and damaged nervous tissue

A

Microglial cells or Microgliocytes

95
Q

are cuboidal to columnar cells arranged in a single layer that possess microvilli and cilia.

A

ependymal cells

96
Q

line the ventricles of the brain and central canal of the spinal cord (spaces filled with cerebrospinal fluid, which protects and nourishes the brain and spinal cord)

A

ependymal Cells

97
Q

produce, possibly monitor, and assist in the circulation of cerebrospinal fluid. They also form the blood–cerebrospinal fluid barrier

A

ependymal cells

98
Q

they form the myelin sheath around axons of PNS

A

Schwann cell

99
Q

A single oligodendrocyte myelinates several axons, but each of these glial cells myelinates a single axon

A

Schwann cell or neurolemmocyte

100
Q

participate in axon regeneration, which is more easily accomplished in the PNS than in the CNS.

A

Schwann cell

101
Q

These flat cells surround the cell bodies of neurons of PNS ganglia; provide structural support; regulate the exchanges of materials between neuronal cell bodies and interstitial fluid

A

satellite cells

102
Q

The outer nucleated cytoplasmic layer of the Schwann cell, which encloses the myelin sheath, is the

A

neurolemma (sheath of Schwann)

103
Q

aids regeneration by forming a regeneration tube that guides and stimulates regrowth of the axon in PNS

A

neurolemma

104
Q

Gaps in the myelin sheath

A

myelin sheath gaps (nodes of Ranvier)

105
Q

puts forth about 15 broad, flat processes that spiral around CNS axons, forming a myelin sheath

A

oligodendrocyte

106
Q

No neurolemma; few nodes of Ranvier; display little regrowth after injury

A

Axons in the CNS wrapped with oligodendrocytes

107
Q

Neuronal cell bodies are often grouped together

A

in clusters

108
Q

The axons of neurons are usually grouped together in

A

bundles

109
Q

widespread regions of nervous tissue are grouped together as either

A

gray matter or white matter

110
Q

refers to a cluster of neuronal cell bodies located in the PNS; closely associated with cranial and spinal nerves

A

ganglion

111
Q

a cluster of neuronal cell bodies located in the CNS

A

nucleus

112
Q

is a bundle of axons that is located in the PNS.

A

axons

113
Q

is a bundle of axons that is located in the CNS; interconnect neurons in the spinal cord and brain

A

Tracts

114
Q

is composed primarily of myelinated axons.

A

white matter

115
Q

contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia

A

gray matter

116
Q

It appears grayish, rather than white, because of the

A

Nissl bodies

117
Q

in the brain, a thin shell of ______ covers the surface of the largest portions of the brain, the cerebrum and cerebellum

A

gray matter

118
Q

They communicate with one another using two types of electrical signals:

A

graded and action potentials

119
Q

perception, the conscious awareness of a sensation, is primarily a function of the

A

cerebral cortex

120
Q

a type of motor neuron that synapses with a lower motor neuron farther down in the CNS in order to contract a skeletal muscle

A

upper motor neuron

121
Q

a type of motor neuron that directly supplies skeletal muscle fibers

A

lower motor neuron

122
Q

The production of graded potentials and action potentials depends on two basic features of the plasma membrane of excitable cells:

A

the existence of a resting membrane potential
and the presence of specific types of ion channels.

123
Q

an electrical potential difference (voltage) across the membrane. In excitable cells, this voltage is termed the

A

resting membrane potential

124
Q

a concentration (chemical) difference plus an electrical difference

A

electrochemical gradient

125
Q

The electrical signals produced by neurons and muscle fibers rely on four types of ion channels:

A

leak channels
ligand-gated channels
mechanically gated channels
voltage-gated channels:

126
Q

channels are found in nearly all cells, including the dendrites, cell bodies, and axons of all types of neurons

A

leak channels

127
Q

opens and closes in response to the binding of a ligand (chemical) stimulus.

A

ligand-gated channel

128
Q

The neurotransmitter acetylcholine opens cation channels that allow Na+ and Ca2+ to diffuse __ and K+ to diffuse___

A

inward; outward

129
Q

opens or closes in response to mechanical stimulation in the form of vibration (such
as sound waves), touch, pressure, or tissue stretching

A

mechanically gated channel

130
Q

gated channels are those found in auditory receptors in the ears, in receptors that monitor stretching of internal organs, and in touch receptors and pressure receptors in the skin.

A

mechanically gated channel

131
Q

channels are located in the dendrites of some sensory neurons, such as pain receptors, and in dendrites and cell bodies of interneurons and motor neurons

A

ligand-gated channel

132
Q

opens in response to a change in membrane potential (voltage); participate in the generation and conduction of nerve impulses in the axons of all types of neurons.

A

voltage-gated channel

133
Q

potential exists because of a small buildup of negative ions in the cytosol along the inside of the membrane, and an equal buildup of positive ions in the extracellular fluid (ECF) along the outside surface of the membrane

A

resting membrane potential

134
Q

contains equal numbers of positive and negative charges and is electrically neutral.

A

The cytosol or extracellular fluid

135
Q

A cell that exhibits a membrane potential is said to be

A

polarized

136
Q

The resting membrane potential of a cell can be measured in the following way:

A

The tip of a recording microelectrode is inserted inside the cell, and a reference electrode is placed outside the cell in the extracellular fluid.

137
Q

The resting membrane potential arises from three major factors

A

(1) unequal distribution of ions in the ECF and cytosol
(2) inability of most anions to leave the cell,
and
(3) the electrogenic nature of the Na+–K+ ATPases.

138
Q

The CNS contains billions of neurons organized into complicated networks; functional groups of neurons that process specific types of information

A

neural circuits

139
Q

Degeneration of the distal portion of the axon and myelin sheath is called

A

Wallerian degeneration

140
Q

major factor that contributes to the resting membrane potential is the unequal distribution of various ions in extracellular fluid and cytosol

A

Unequal distribution of ions in the ECF and cytosol

141
Q

Because the plasma membrane typically has more K+ leak channels than Na+ leak channels, the number of potassium ions that diffuse down their concentration gradient out of the cell into the ECF is greater than the number of sodium ions that diffuse down their concentration gradient from the ECF into the cell.

A

Unequal distribution of ions in the ECF and cytosol

142
Q

As more and more positive potassium ions exit, the inside of the membrane becomes

A

increasingly negative

143
Q

They cannot follow the K+ out of the cell
because they are attached to nondiffusible molecules such as ATP and large proteins

A

Inability of most anions to leave the cell.

144
Q

Membrane permeability to Na+ is very low because there are only a few sodium leak channels. The small inward Na+ leak and outward K+ leak are offset by the Na+–K+ ATPases (sodium–potassium pumps). Recall that the Na+–K+ ATPases expel three Na+ for each two K+ imported

A

Electrogenic nature of the Na+–K+ ATPases

145
Q

Since these pumps remove more positive
charges from the cell than they bring into the cell, they ____ which means they contribute to the negativity of the resting membrane potential. Their total contribution, however, is very small: only −3 mV of the total −70 mV resting membrane potential in a typical neuron

A

electrogenic,

146
Q

a small deviation from the resting membrane potential that makes the membrane either more polarized (inside more negative) or less polarized (inside less negative).

A

graded potential

147
Q

occurs when a stimulus causes mechanically gated or ligand-gated channels to open or close in an excitable cell’s plasma membrane

A
148
Q

Hence, graded potentials occur mainly in

A

dendrites and cell body of a neuron.

149
Q

This mode of travel by which graded potentials
die out as they spread along the membrane is known as

A

decremental conduction

150
Q

process by which graded potentials add together

A

summation

151
Q

when a graded potential occurs in the dendrites or cell body of a neuron in response to a neurotransmitter

A

postsynaptic potential

152
Q

is a sequence of rapidly occurring events that decrease and reverse the membrane potential and then eventually restore it to the resting state.

A

Action potential

153
Q

once a nerve impulse is generated the amplitude of a nerve impulse is always the

A

same and does not depend on stimulus intensity

154
Q

In other words, a nerve impulse either occurs completely or it does not occur at all. This characteristic of a nerve impulse is known as the

A

all or none principle

155
Q

The slower opening of voltage-gated K+ channels and the closing of previously open voltage-gated Na+ channels produce the

A

repolarizing phase of the nerve impulse.

156
Q

allows inactivated Na+ channels to revert to the resting state

A

Repolarization

157
Q

is the period of time during which a second nerve impulse can be initiated, but only by a larger-than-normal stimulus

A

relative refractory period

158
Q

mode of conduction is called

A

propagation

159
Q

Factors That Affect the Speed of ­Propagation

A

amount of myelination, axon diameter,
and temperature

160
Q

largest diameter axon; The axons of sensory neurons that propagate impulses associated with touch, pressure, position of joints, and some thermal and pain sensations

A

A fibers

161
Q

conduct sensory nerve impulses from the viscera to the brain and spinal cord. They also constitute all of the axons of the autonomic motor neurons that extend from the brain and spinal cord to the ANS relay stations called autonomic ganglia.

A

B fibers

162
Q

Autonomic motor fibers that extend from autonomic ganglia to stimulate the heart, smooth muscle, and glands are

A

C fibers

163
Q

is a type of neurotransmitter receptor that contains a neurotransmitter binding site and an ion channel.

A

ionotropic receptor

164
Q
A

ANAPHY (10 decks)

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