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Anatomy & Physiology > Nervous System > Flashcards

Nervous System Flashcards

1
Q

Nervous system

A

all nervous tissues in the body

Intricate network of billions of neurons and many more neuroglia

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2
Q

three functions of the nervous system

A

sensory
motor
integration

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3
Q

sensory function

A

all incoming information about the external and internal environments; transmitted as
nerve impulses to the central nervous system to be integrated

detect internal and external stimuli; carried to the brain and spinal cord through cranial
and spinal nerves

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4
Q

motor function

A

initiates all voluntary movements; responds rapidly to help adjust body processes using
nerve impulses; includes all commands that control muscles and glands

once sensory information is integrated, the nervous system may elicit an appropriate
motor response by activating effectors (muscles and glands) through cranial and spinal nerves

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5
Q

integration/ intergrative

A

responsible for our perceptions, behaviors, memories, and much more; includes all
higher level thinking, processing, and the connection between sensory and motor

integrates (processes) sensory information by analyzing and storing some of it and
by making decisions for appropriate responses

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6
Q

neurology

A

the branch of medical science that deals with the normal functioning and disorders of the nervous system

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7
Q

2 main subdivisions

A

Central nervous system

peripheral nervous system

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8
Q

Central Nervous System

A

brain and spinal cord

Processes incoming sensory info and is the source of thoughts, emotions, and memories

most nerve impulses that stimulate muscles to contract and glands to secrete originate in
the CNS

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9
Q

Peripheral Nervous system

A

all nervous tissue outside the CNS

nerves
ganglion
enteric plexuses
sensory receptors

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10
Q

Nerve

A

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

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11
Q

how many pairs of cranial nerves

A

12 pairs of cranial nerves

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12
Q

how many pairs of spinal nerves

A

31 pairs of spinal nerves

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13
Q

ganglion ( ganglia)

A

small masses of nervous tissue, consisting primarily of neuron cell bodies, that are located outside the brain and spinal cord

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

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14
Q

enteric plexuses

A

extensive networks of neurons located in the walls of organs of the gastrointestinal tract; help regulate the digestive system

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15
Q

sensory receptor

A

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

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16
Q

The PNS is divided into

A

Somatic nervous system

autonomic nervous sytem

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17
Q

Somatic nervous system

A

voluntary

Sensory neurons that convey info to the CNS

Motor neurons that conduct impulses from the CNS to skeletal muscles

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18
Q

Autonomic nervous system

A

involuntary

Sensory neurons that convey info to the CNS from autonomic sensory receptors (visceral organs)

Motor neurons that conduct nerve impulses from the CNS to smooth and cardiac muscle,
and glands

Motor part of the ANS consists of two branches: sympathetic (fight or flight) and
parasympathetic (rest and digest) divisions

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19
Q

enteric nervous system

A

involuntary; “brain of the gut”

100 million neurons in enteric plexuses that extend most of the length of the
gastrointestinal tract

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20
Q

2 types of cells of the nervous system

A

neurons and neuroglia

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21
Q

neurons

A

nerve cells

excitability
stimulus
action potential (impulse)

have 3 parts

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22
Q

electrical excitability

A

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

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23
Q

stimulus

A

any change in the environment that is strong enough to initiate an action potential

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24
Q

action potential (impulse)

A

an electrical signal that propagates along the surface of the membrane of a neuron or a muscle fiber

Neurons communicate with one another by means of nerve action potentials (nerve impulses)

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25
Q

3 parts of neuron

A

cell body soma
dendrites
axon

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26
Q

cell body (soma)

A

contains a nucleus surrounded by cytoplasm that includes typical organelles; multiple dendrites and a single axon extend from the cell body

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27
Q

dendrites

A

receiving or input part of the neuron (along with the cell body); short, tapering, highly branched; tree-shaped

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28
Q

axon

A

conducts nerve impulses toward another neuron, a muscle cell, or a gland cell; long, cylindrical projection that often joins the cell body at a cone shaped
elevation called the axon hillock

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29
Q

nerve impulses usually arise

A

at the axon hillock and travel along the axon

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30
Q

axon collaterals

A

side branches

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31
Q

axon terminals

A

fine processes at the ends of the axons and axon collaterals

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32
Q

Synapse

A

the site where two neurons or a neuron and an effector cell can communicate

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33
Q

synaptic end bulbs

A

the tips of most axon terminals that contain synaptic vesicles (tiny sacs that store neurotransmitters)

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34
Q

structural classification of neurons

A

classified according to the number of processes extending from the cell body

multipolar
bipolar
unipolar

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35
Q

multipolar neurons

A

usually have several dendrites and one axon; most neurons in the brain and spinal cord are of this type

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36
Q

bipolar neurons

A

have one main dendrite and one axon; found in the retina of the eye, in the inner ear, and in the olfactory area of the brain

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37
Q

unipolar neurons

A

have dendrites and one axon that are fused together to form a continuous process that emerges from the cell body; most are sensory receptors; most are located in the ganglia of spinal and cranial nerves

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38
Q

functional classification of neurons

A

classified according to the direction in which the nerve impulse is conveyed with respect to the CNS

sensory
motor
interneurons

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39
Q

sensory ( afferent ) neurons

A

either contain sensory receptors at their distal ends (dendrites) or are located just after sensory receptors that are separate cells; action potential is generated and conveyed into the CNS; most are unipolar

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40
Q

motor ( efferent) neurons

A

convey action potentials away from the CNS to effectors (muscles and glands) in the PNS; most are multipolar

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41
Q

interneurons ( associate neurons)

A

located within the CNS between sensory and motor neurons; integrate incoming sensory information from sensory neurons and then elicit a motor response by activating the appropriate motor neurons; most are multipolar

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42
Q

neuroglia

A

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

neuroglia= glia

Make up about half the volume of the CNS

Actively participate in the activities of nervous tissue

Smaller than neurons, but are 5-25 times more numerous

Do not generate or conduct nerve impulses, can multiply and divide in the mature
nervous system

6 types

43
Q

types of neuroglia in CNS

A

astrocytes, oligodendrocytes, microglia, and ependymal cells

44
Q

types of neuroglia in PNS

A

Schwann cells and satellite cells

45
Q

myelination

A

axons with a myelin sheath are said to be myelinated, those without are unmyelinated

Neuroglia cells produce myelin sheaths by wrapping themselves around and around axons (sometimes 100 layers on one axon)

46
Q

myelin sheath

A

a many-layered covering composed of lipid and protein that surrounds the axons
of most neurons; insulates the axon of a neuron and increases the speed of nerve impulse conduction

47
Q

Myelination in PNS

A

schwann cells

48
Q

Myelination in CNS

A

Oligodendrocytes

49
Q

Nodes of Ranvier

A

gaps in the myelin sheath at intervals along the axon

50
Q

Collections of Nervous tissue

A

ganglion
nucleus
nerve
tract

51
Q

Nucleus

A

a cluster of neuronal cell bodies located in the CNS

52
Q

Nerve

A

a bundle of axons that is located in the PNS

cranial nerves connect to the brain to the periphery

spinal nerves connect the spinal cord to the periphery

53
Q

tract

A

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

54
Q

widespread regions of nervous tissue are grouped together as

A

gray or white matter

in brain and spinal cord, some are white and glistening, others appear gray

55
Q

white matter

A

composed primarily of myelinated axons; whitish color of myelin makes it
appear white

blood vessels

56
Q

gray matter

A

contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and
neuroglia; appears grayish because the cellular organelles impart a gray color and little or no myelin

blood vessels

57
Q

In spinal cord, the outer white matter

A

surrounds an inner core of gray matter

58
Q

in the brain, a thin shell of gray matter ( cortex)

A

covers the surface of the largest portions of the brain, the cerebrum, and cerebellum

59
Q

Generation of action potentials in muscle cells and neurons depends on 2 basic features of the plasma membrane

A

the existence of a resting membrane potential

the presence os specific types of ion channels

60
Q

existence of a resting membrane potential

A

a difference in the amount of electrical
charge on the inside of the plasma membrane as compared to the outside; like voltage stored in a battery

A cell that has a membrane potential is said to be polarized

61
Q

presence of specific types of ion channels

A

the flow of ions in living tissues

constitutes electrical currents

62
Q

ion channels

A

When they are open, ion channels allow specific ions to diffuse across the plasma
membrane from where the ions are more concentrated to where they are less
concentrated

Positively charged ions will move toward a negatively charged area and vice
versa

The flow of current can change the membrane potential

63
Q

leak channels

A

type of ion channel that allows a small but steady stream of ions to leak across the membrane

64
Q

gated channels

A

type of ion channel that opens and closes on command

65
Q

voltage- gated channels

A

type of ion channel that opens in response to a change in membrane potential; used to generate and conduct action potentials

66
Q

resting membrane potential

A

In a resting neuron, the outside surface of the plasma membrane has a positive
charge and the inside surface has a negative charge

The separation of positive and negative electrical charges is a form of potential
energy

Most negatively charged ions inside the cell are not free to leave, which
contributes to the negativity inside the cell
Arises from the unequal distributions of various ions in cytosol and extracellular
fluid

67
Q

action potential (impulse)

A

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

68
Q

threshold

A

a critical level of depolarization caused by a stimulus that leads to the generation of
an action potential

69
Q

2 main phases of action potential

A

depolarizing

repolarzing

70
Q

all-or-none principle

A

as long as a stimulus is strong enough to cause depolarization to
threshold, an action potential occurs; a stronger stimulus will generate the same action potential; a weak stimulus that fails to cause a threshold-level depolarization does not elicit an action potential

71
Q

refractory period

A

the brief time after an action potential begins during which a muscle fiber or
neuron cannot generate another action potential

72
Q

conduction of nerve impulses

A

propagation
continous conduction
saltatory conduction

73
Q

propagation

A

a mode of conduction in which nerve impulses travel from where they arise
(usually at the axon hillock) along the axon to the axon terminals

74
Q

continous conduction

A

the type of action potential conduction that occurs in unmyelinated axons

Each adjacent segment of the plasma membrane depolarizes to threshold and generates an action potential that depolarizes the next patch of the membrane

75
Q

saltatory conduction

A

the type of action potential conduction that occurs in myelinated axons

Current is carried through the interstitial fluid surrounding the myelin sheath and through
the cytosol from one node to the next; impulse appears to leap from node to node; travels much farther in the same time interval

76
Q

Axons with large diameters

A

conduct faster than small

77
Q

myelinated axons conduct

A

faster than unmyelinated

78
Q

axons with the largest diameters

A

are all myelinated

79
Q

axons with the smallest diameters

A

are unmelinated

80
Q

axons conduct faster when

A

when warmed

81
Q

axons conduct lower

A

when cooled

82
Q

synaptic transmission

A

a series of events by which neurons communicate with other neurons or
with effectors

83
Q

presynaptic neuron

A

the neuron sending the signal

84
Q

postsynaptic neuron

A

the neuron receiving the message

85
Q

synaptic cleft

A

a tiny space filled with interstitial fluid between the pre and postsynaptic
neurons

86
Q

2 types of synapses

A

Electrical

chemical

87
Q

electrical

A

nerve impulses conduct directly between the plasma membranes of adjacent
neurons through gap junctions

rapid conduction and coordination

88
Q

gap junctions

A

tunnel-like structures that connect adjacent cells and allow ions to flow through; visceral smooth muscle, cardiac muscle, and the brain

89
Q

chemical

A

most nerve impulses; a nerve impulse in a presynaptic neuron causes the
release of neurotransmitter molecules into the synaptic cleft; neurotransmitters produce a nerve impulse in the postsynaptic neuron

90
Q

events at a chemical synapse

A

A nerve impulse arrives at a synaptic end bulb of a presynaptic axon

The depolarizing phase of the nerve impulse causes Ca to flow into the synaptic end bulb

An increase in the concentration of Ca inside the synaptic end bulb triggers the release of
thousands of neurotransmitter molecules into the synaptic cleft

The neurotransmitter molecules diffuse across the synaptic cleft and bind to neurotransmitter receptors in the postsynaptic neuron’s plasma membrane

Binding of neurotransmitter molecules opens ion channels, which allows certain ions to flow across the membrane

As ions flow through the opened channels, the voltage across the membrane changes

If a depolarization occurs in the postsynaptic neuron and reaches threshold, then it triggers one or
more nerve impulses

91
Q

3 ways neurotransmitters are removed for normal synaptic function

A

some of the released neurotransmitter molecules diffuse away from the synaptic cleft

some are destroyed by enzymes

many are actively transported back into the neuron that released them (reuptake) or
transported into neighboring neuroglia (uptake)

92
Q

neurotransmitters

A

about 100 are known or suspected
most are synthesized and loaded into synaptic vesicles in the synaptic end bulbs, close to their site of release
ACh

93
Q

acetycholine

A

one of the best-studied; released by many PNS neurons and some CNS neurons

Excitatory neurotransmitter at some synapses (neuromuscular junction); also known to be
inhibitory at other synapses (slow heart rate)

94
Q

several amino acids are neurotransmitters in the CNS

A

glutamate and aspartate

gamma aminobutyric acid and glycine

95
Q

glutamate and aspartate

A

powerful excitatory effects

96
Q

gamma aminabutyric acid ( GABA)

A

important inhibitory neurotransmitters

Valium and other antianxiety drugs enhance the action of GABA

97
Q

norepinephrine

A

plays roles in arousal (awakening from deep sleep), dreaming, and regulating mood

98
Q

dopamine

A

active during emotional responses, addictive behaviors, and pleasurable experiences; regulates some aspects of movement

99
Q

serotonin

A

thought to be involved in sensory perception, temperature regulation, control of mood, appetite, and the onset of sleep

100
Q

endorphins

A

the body’s natural painkillers; linked to improved memory, and feelings of pleasure
or euphoria

101
Q

nitric oxide

A

different because it is not synthesized in advance and packaged into synaptic
vesicles; formed on demand, diffuses out of cells that produce it and into neighboring cells and acts immediately; plays a role in learning and memory

102
Q

carbon monoxide

A

not produced in advance and packaged into synaptic vesicles; formed as
needed and diffuses out of cells that produce it into adjacent cells; excitatory; produced in the brain; might protect against excess neuronal activity and might be related to dilation of blood vessels, memory, olfaction, vision, thermoregulation, insulin release, and anti-inflammatory activity

103
Q

demyelination

A

loss or destruction of myelin sheaths around axons in the CNS or PNS

104
Q

neuropathy

A

any disorder that affects the nervous system but particularly a disorder of a cranial or
spinal nerve

Anatomy & Physiology (15 decks)

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