Chapter 7 - Nervous System Flashcards
1
Q
the nervous sytem enables organisms to
A
receive and respond to stimuli from their external and internal environments
2
Q
neurons
A
functional units of nervous system
3
Q
neuron converts stimuli into
A
electrochemical signals
4
Q
electrochemical signals are
A
conducted through nervous system
5
Q
the nervous system responds ____ to stimuli than the endocrine system
A
more rapidly
6
Q
the neuron consists of
A
elongated cell consisting of several dendirtes, a body, a single axon
7
Q
dendrites
form & fxn
A
cytoplasmic extensions that receive information and transmit it towards the cell body
8
Q
cell body (soma)
A
contains nucleus and controls metabolic activity of the neuron
9
Q
axon
A
long cellular process that transmits impulses away from teh cell body
10
Q
most mammalian neuron body and axon are
A
sheathed by insulating substance - myelin
11
Q
myelin
A
sheates body and axon of neuron
allows axons to conduct impulses faster
12
Q
myelin produced by
A
glial cells
13
Q
oligodendrocytes
A
produce myelin in central nervous system
14
Q
schwann cells
A
produce myelin in peripheral nervous system
15
Q
nodes or Ranvier
A
gaps between segments of myelin
16
Q
axons end as swellings known as
A
synaptic terminals
17
Q
neurotransmitters released from ____ into _____
A
synaptic terminals;
synapse (synaptic cleft)
18
Q
synapse (synaptic cleft)
A
gap between axon terminals of one cell and dendrites of next cell
19
Q
axons travelling from spine to tip of foot may be
A
very long
20
Q
neurons are specialized to
A
receive signals from sensory receptors or other neurons in body and transfer information along length of axon
21
Q
action potentials are
A
impulses that travel the length of the axon and invade the nerve terminal
22
Q
action potentails cause
A
release of neurotransmitters into the synapse
23
Q
resting potential
A
potential difference between extracellular space and intracellular space when neuron is at rest
24
Q
even at rest, a neuron is
A
polarized
25
potential difference is the result of
unequal distribution of ions between inside and outside of the cell
26
typical resting membrane potential is
-70 millivolts
27
typical resting membrane potential of -70 mv means that the inside of the neuron is
more negative than the outside
28
the potential difference is due to
selective ionic permeability of neuronal cell membrane
29
the potential difference is maintained by
active transport by Na+/K+ pump
30
concentration of K+ is higher \_\_\_\_\_
the concentration of Na+ is higher \_\_\_\_
inside; outside
31
in addition to K+/Na+ difference; negatively charged proteins are
trapped inside cell
32
the resting potential is created because the neuron is selectively permeable to
K+
33
selective permeability of neuron to K+ means that
K+ diffuses down its concentration gradient, leaving net negative charge inside
34
neurons are impermeable to
Na+
35
because neurons are impermeable to Na+
cell remains polarized
36
ionic gradients are restored by
Na+/K+ pumps
37
the Na+/K+ pump operates using ____ for energy
ATP
38
the Na+/K+ pump transports _____ out for every ____ transported into the cell
3 Na+
2 K+
39
nerve cell body receives both ____ and _____ impulses from other cells
excitatory and inhibitory impulses
40
action potential generated when
cell becomes sufficiently excited
or
depolarized (less negative)
41
the minimum threshold membrane potential is
-50 mV
42
the minimum threshold membrane potential is the level at which
action potential is initiated
43
Na+ wants to go ____ the cell because \_\_\_\_\_
into;
it is more negative inside hte cell (electrical gradient) and there is less Na+ inside (chemical gradient)
44
in response to changes in voltage,
ion channels located in nerve cell membrane open
45
voltage-gated ion channels
ion channels located in nerve cell membrane that open in response to changes in voltage are called
46
action potential begins when
voltage-gated Na+ channel open in response to depolarization
47
voltage-gated Na+ channels open in response to
depolarization
48
the opening of the voltage-gated Na+ channels allows Na+ to
rush down electrochemical gradient into the cell
49
depolarization leads to opening the voltage-gated Na+ channels, allowing Na+ to rush down its electrochemical gradient into the cell
this causes
rapid further depolarization of that segment of the cell
50
after the cascade of depolarization, the voltage-gated Na\_ channels close and then
the voltage-gated K+ channels open and K+ rushes out down electrochemical gradient
51
voltage-gated K+ channels opening and allowing K+ ions to rush down the electrochemical gradient allows for
the cell to return to a mor enegative potential
52
repolarization
the cell returning to a more negative potential after the voltage-gated K+ channels open to allow K+ ions to rush down the electrochemical gradient to balance the depolarization of the Na+ ions
53
hyperpolarization
neuron may shoot past resting potential and become even more negative inside than normal
54
refractory period
immediately following action potential, may be very difficult or impossible to initiate another action potential
55
all-or-none response
action potential all-or none response
when threshold membrane potential is reached, action potential with consistent size and duration is produced
nerve fires maximally or not at all
56
stimulus intensity is coded by
frequency of action potentials
57
axons can theoretically propagate action potentials bidirectionally, however, information transfer occurs only
in one direction:
dendrite ---\> synaptic terminal
58
backward information transfer through the axon is impossible because
synapses operate only in one direction
and
refractory periods make backward travel of action potentials impossible
59
speeds of action potentials
different axons can propagate action potentials at different speeds
60
speed of action potential depends on
the greater the diameter
and
the more heavily it is myelinated
the faster the impulses
61
myelin increases conduction of velocity down the axon by
insulating segments of hte axon
membrane permeable to ions only at nodes of Ranvier
action potential "jumps" from node to node
62
synapse
gap between axon terminal of one neuron and dendrites of another neuron
63
presynaptic neuron
neuron before synapse
64
postsynaptic neuron
neuron after synapse
65
neurons may communicate with
neurons
muscles or glands
66
effector cell
The muscle, gland or organ cell capable of responding to a stimulus at the terminal end of an efferent neuron or motor neuron.
67
neurotransmitters
chemical messengers stored in membrane-bound vesicles at the nerve terminal
68
nerve terminal contains thousands of membrane-bound vesciles full of
neurotransmitters
| (chemical messengers)
69
when the action potential arrives at the nerve terminal and depolarizes it
the synaptic vesicles fuse with the presynaptic membrane and release neurotransmitters into the synapse
70
once the synaptic vesicles fuse with presynaptic membrane and release neurotransmitters into the synapse,
the neurotransmitter...
diffuses across the synapse and acts on receptor proteins embedded in the postsynaptic membrane
71
neurotransmitters diffuse across the synapse and act on
receptor proteins on the post-synaptic membrane
72
the neurotransmitter can lead to ____ on the post-synaptic cell and consequent \_\_\_\_\_
depolarization;
firing an action potential
73
how is neurotransmitter removed from synapse?
(3)
1. taken back up into nerve terminal via uptake carrier (protein)
2. degraded by enzymes located in the synapse
3. diffuse out of synapse
74
neurotransmitmter may be taken back into the nerve terminal from synapse via
a protein: uptake carrier
75
enzymes that may degrade neurotransmitters in the synapse
acetylcholinesterase inactivates neurotransmitter acetylcholine
76
curare
| (drug)
blocks post-synaptic acetylcholine receptors so that acetylcholine is unable to interact with receptor
leads to paralysis by blocking nerve impluses to muscles
77
botulism toxin
prevents realease of acetylcholine from pre-synaptic membrane
results in paralysis
78
anti-cholinesterases
used as nerve gases and in insecticide parathion
inhibit activity in acetylcholinesterase enzyme
acetylcholine is not degraded in the synapse and continues to affect post-synaptic membrane
no coordinated muscular contractions can take place
79
afferent neurons
sensory neurons
80
efferent neurons
motor neurons
81
afferent neurons carry sensory information about
external or internal environment **to** the brain or spinal cord
82
efferent neurons carry motor commands
**from** brain or spinal cord **to **various parts of the body (e.g. muscles, glands)
83
interneurons
only in local circuits
linking sensory and motor neurons in the brain and spinal cord
cell bodies and nerve terminals in same location
84
nerves are
bundles of axons covered with connective tissue
85
plexus
network of nerve fibers
86
ganglia
neuronal cell bodies clustered together in the periphery
87
nuclei
neuronal cell bodies clustered together in the central nervous system
88
nervous system divided into two major systems
central nervous system
peripheral nervous system
89
central nervous system
brain
spinal cord
90
peripheral nervous system
somatic
autonomic
91
autonomic nervous system
sympathetic
parasympathetic
92
central nervous system (CNS) consists of
brain and spinal cord
93
brain
composition
mass of neurons in the skull
94
brain
function
interpreting sensory information
forming motor plans
cognitive functions (thinking)
95
brain
structure
outer portion - gray matter (cell bodies)
inner portion - white matter (myelinated axons)
96
brain divided into three parts
forebrain
midbrain
hindbrain
97
forebrain
composition
telencephalon
diencephalon
98
telencephalon
cerebral cortex
olfactory bulb
99
cerebral cortex
highly convoluted gray matter that can be seen on teh surface of the brain
processes and integrates sensory input and motor responses
important for memory and creative thought
100
diencephalon
thalamus
hypothalamus
101
thalamus
relay and integration center for spinal cord and cerebral cortex
102
hypothalamus
controls visceral functions
e.g. hunger, thirst, sex drive, water balance, blood pressure, temperature regulation
control endocrine system
103
midbrain
composition
mesencephalon
104
midbrain
(mesencephalon)
function
relay center for visual and auditory impulses
motor control
105
hindbrain
location
posterior part of brain
106
hindbrain
composition
cerebellum
pons
medulla
107
cerebellum
modulate motor impulses initiated by cerebral cortex
maintenance of balance, hand-eye coordination, timing of rapid movements
108
pons
relay center
allows cortex to communicate with cerebellum
109
medulla oblongata
controls vital fxns
breathing, heart rate, gi activity
110
brainstem
composition
midbrain, pons, medulla
111
spinal cord
elongated extension of brain
conduit for sensory information to the brain
motor information from the brain
112
reflexes
spinal cord can integrate simple motor responses by itself
113
spinal cord
structure
outer white matter - motor and sensory axons
inner gray matter area - nerve cell bodies
114
dorsal horn
sensory information enters spinal cord through the dorsal horn
115
dorsal root ganglia
contain cell bodies of sensory neurons
116
ventral horn
all motor information exits spinal cord through ventral horn
117
for simple reflexes
e.g. knee-jerk reflex
sensory fibers (entering through dorsal root ganglion) synapse directly on ventral horn moter fibers
118
example of other reflexes:
interneurons between sensory and motor fibers
allow for some preocessing in spinal cord
119
peripheral nervous system (PNS)
consists of
nerves
ganglia
120
sensory nerves which enter CNS and motor nerves which leave CNS are part of the
PNS
121
PNS two primary divisions
somatic nervous system
autonomic nervous system
122
both somatic and autonomic nervous systems have both
sensory and motor components
123
somatic nervous system
innervates skeletal muscles and is resopnsible for VOLUNTARY movement
124
autonomic nervous system
aka
involuntary nervous system
125
ANS regulates
body's intenral environment without aid of conscious control
126
autonomic innervation of body includes both
sensory and motor fibers
127
ANS innervates these two types of muscle
cardiac
smooth muscle
128
smooth muscle
located in blood vessels, digestive tract, bladder, bronchi
129
ANS innervates smooth muscle, which is located in the bladder, digestive tract, bronchi, blood vessels
so it is not surprising that the ANS is important in
excretory processes, respiration, gastrointestinal motility and reproductive processes
130
ANS composed of two subdivisions
sympathetic nervous system
parasympathetic nervous system
131
parasympathetic nervous system and sympathetic nervous system act ______ to each other
in opposition
132
sympathetic nervous system
"fight or flight"
increases blood pressure and heart rate
increases blood flow to skeletal muscles
decreases gut motility
dilates bronchioles to increase gas exchange
133
sympathetic nervous system uses _____ as it's primary neurotransmitter
norepinephrine
134
parasympathetic nervous system
acts to conserve energy and restore activity levels following exertion
"rest and digest"
lowers heart rate
increase gut motility
135
vagus nerve
parasympathetic nerve
innervates thoracic and abdominal vicsera
136
parasympathetic nervous system uses ____ as it's primary neurotransmitter
acetylcholine
137
the eye and ear are examples of
specialized receptors designed to detect stimuli
138
the eye detects
light energy
139
after detecting light energy, the eye transmits information about ____ to the \_\_\_\_\_
intensity, color, shape to the brain
140
sclera
thick, opaque layer covering the eyeball
"white" of the eye
141
choroid layer
beneath the sclera
helps supply retina with blood
dark, pigmented area
reduces reflection in the eye
142
retina
innermost layer of the eye
contains phtoreceptors that sense light
143
cornea
transparent layer at the front of the eye
bends and focuses light rays
144
pupil
rays travel through this opening
145
diameter of pupil is controlled by
pigmented, muscular iris
146
iris
responds to intensity of light and surroundings (makes pupil constrict)
147
lens
light continues through lens after going through pupil
suspended behind pupil
focuses the image onto the retina
148
the shape and focal length of the lens is controlled by
ciliary muscles
149
photoreceptors
in the retina
transduce light into action potentials
150
two main types of photoreceptors
cones
rods
151
cones
type of photoreceptor in retina
respond to high-intensity illumination
sensitive to color
152
rods
type of photoreceptor in retina
detect low-intensity illumination
important in night vision
153
cones and rods contain various pigments that
absorb specific wavelengths of light
154
cones and pigments (absorb wavelengths of light)
contain 3 different pigments
absorb red, green, blue wavelengths
155
rod and pigments (absorb wavelengths of light)
rod pigment: rhodopsin
absorbs a single wavelength
156
photoreceptor cells synapse into
bipolar cells
157
bipolar cells synapse into
ganglion cells
158
axons of the ganglion cells bundle to form
optic nerves
159
optic nerves
conduct visual information to the brain
160
blind spot
point at which the optic nerve exits the eye
photoreceptors not present here
161
fovea
small area of retina
densely packed with cones
high acuity vision
162
vitreous humor
jellylike material composing most space between lens and retina
maintains shape and optical properties of eye
163
aqueous humor
formed by eye
exits through ducts to join venous blood
164
disorders of the eye
5
myopia
hyperopia
astigmatism
cataracts
glaucoma
165
myopia
| (nearsightedness)
image is focused in front of retina
166
hyperopia
| (farsightedness)
image is focused behind retina
167
astigmatism
caused by
irregularly shaped cornea
168
cataracts develop when
lens becomes opaque
light cannot enter the eye and blindness results
169
glaucoma
increase of pressure in the eye
due to blocking of outflow of aqueous humor
170
ear
function
transduces pressure waves (sound energy) into impulses perceived by brain as sound
171
sound waves pass through ___ regions as they enter the ear
172
regions sound waves pass through when entering ear
1. outer ear
2. middle ear
3. inner era
173
outer ear
consists of
auricle (external ear)
auditory canal
174
at the end of the auditory canal is the
tympanic membrane (eardrum)
of the middle ear
175
tympanic membrane (eardrum)
vibrates at same frequency as incoming sound
176
middle ear
1. tympanic membrane (eardrum)
2. ossicles (bones) (3- malleus, incus, stapes)
3. oval window
177
three ossicles (bones) of the ear
malleus
incus
stapes
178
fxn of ossicles
amplify the stimulus
transmit stimulus through oval window
179
oval window (last part of middle ear) leads to
inner era
180
inner ear is filled with
fluid
181
inner ear consists of
cochlea
vestibular apparatus
182
vestibular apparatus
maintains equilibrium
183
vibration of the ossicles exerts pressure on \_\_\_\_\_
fluid of the cochlea
184
pressure on the fluid of the cochlea stimulates \_\_\_\_
hair cells in the basilar membrane to transduce pressure into action potentials
pressure ----\> action potentials via hair cells in basilar membrane
185
action potentials transduced by hair cells in the basilar membrane travel via the _____ to the ____ for processing
auditory (cochlear) nerve
brain
186
basilar membrane
within the cochlea of the inner ear
stiff structural element
separates two liquid-filled tubes that run along the coil of the cochlea, the scala media and the scala tympani
187
protozoa nervous system
unicellular organisms - no organized nervous system
188
single celled organisms may respond to stimuli such as
touch
heat
light
chemicals
189
cindaria nervous system
simple nervous system - nerve net
network of nerve cells
may have limited centralization
190
jellyfish nervous system
clusters of cells and pathways
coordinate movements required for swimming
191
annelida nervous system
central nervous system
192
the central nervous system of annelida (earthworm) consists of
ventral nerve cord
anterior "brain" of fused ganglia
nerve pathways between receptors to effectors
193
arthropoda nervous system
brains similiar to annelids
more specialized organs
194
examples of complex organs in arthropoda
(related to nervous system)
compound or simple eyes
tympanum for detecting sound
195
