Chapter 2 Neurons Flashcards
1
Q
The human nervous system is comprised of two kinds of cells:
A
Neurons Glia
2
Q
How many neurons does the human brain contain
A
approximately 100 billion
3
Q
Glia
A
support cells
4
Q
Neocortex contains how many neurons?
A
12-15 billion
5
Q
How many neurons does spinal cord contain?
A
1 billion neurons
6
Q
How many neurons does the cerebellum contain?
A
~70 billion neurons
7
Q
Cerebrum
A
cerebral cortex (newer structure of the brain), majority of the cells in your brain are
8
Q
Cerebellum
A
little brain with majority of neurons
9
Q
Santiago Ramon y Cajal
A
Artist & neuroscientist Used microscope to study neural tissue First to demonstrate that the individual cells comprising the nervous system remained separate (Neuron Doctrine) He showed that they did not grow into each other as previously believed
10
Q
Father of modern neuroscience
A
Santiago Ramon y Cajal
11
Q
Astrocytes
A
hold neurons in place, give nutrients, dispose of dead cells, may even be involved in communication directing formation of synapses and releasing neurotransmitters involved in communicating directly with neurons, help groups of neurons fire.
12
Q
Ogliodendrocytes
A
form myelin sheath
13
Q
Microglia
A
immune cells, detect unhealthy neurons, attack foreign cells like bacteria
14
Q
Myelin
A
fatty substance helps speed
15
Q
A
Cajal drawing of neuron
16
Q
Neurons have basic cell structures.
True or False?
A
True
17
Q
Cell membrane
A
a structure that separate the inside of the cell from the outside environment
18
Q
Nucleus
A
a structure that contains the chromosomes
19
Q
mitochondrion
A
structure that performs metabolic activities and provides energy that the cells requires
20
Q
Ribosomes
A
sites at which the cell synthesizes new protein molecules
21
Q
Endoplasmic reticulum
A
network of thin tubes that transport newly synthesized proteins to their location
22
Q
Neuron cells are similar to other cells of the body but
A
have a distinctive shape
23
Q
Motor neuron
A
has its soma in the spinal cord and receives excitation from other neurons and conducts impulses along its axon to a muscle
24
Q
Sensory neuron
A
specialized at one end to be highly sensitive to a particular type of stimulation (touch, light, sound, etc.)
Could be sensitive to pressure, frequencies of sound
25
Schwann cells myelinate where?
Peripheral Nervous System
(PNS)
not in the brain
26
ogliodendrocytes myelinate where?
CNS
27
Axon Terminals
Transmitters
28
Dendrites function?
receivers
synaptic receptors to take in info
29
Schwann Cells make?
myelin
30
Axon's function?
conducting fiber
31
Mylelin Sheath's function?
insulating fatty layer that speeds up transmission
of neural impulse
32
Branching fibers with a surface lined with synaptic receptors responsible for bringing information into the neuron
dendrite
33
spines that further branch out and increase the surface area of the dendrite
dendritic spines
34
The greater the surface area of the \_\_\_, the more information it can receive
dendrite
35
Cell body of the neuron
soma
36
Contains the nucleus, mitochondria, ribosomes, and other structures found in other cells
soma
37
responsible for the metabolic work of the neuron
soma
38
Thin fiber of a neuron responsible for transmitting nerve impulses toward other neurons, organs, or muscles
Axon
39
Some neurons are covered with an insulating material called the myelin sheath with interruptions in the sheath known as nodes of Ranvier
Axon neuron
40
The end points of an axon where the release of chemicals to communicate with other neurons occurs
Presynaptic Terminals
41
Afferent axon
refers to bringing information into a structure
ie: sensory neurons: sensing info to central nervous system
42
Efferent axon
refers to carrying information away from a structure
ie: communicating away to a muscle
43
Those whose dendrites and axons are completely contained within a single structure
Interneurons or intrinsic neurons
neither motor or sensory
communicate and process info
44
Neurons vary in size, shape, and function
True or False?
True
45
The shape of a neuron determines it connection with other neurons and contribution to the nervous system
True or False?
True
46
Neuron function is closely related to the shape of a neuron.
True or False?
True
47
Example of neuron shape and function?
Pukinje cells of the cerebellum branch extremely widely within a single plane
flat
48
.
chononicle neuron
49
Presynaptic terminals
end points of an axon where the release of chemicals to communicate with other neurons occurs
50
AKA neuroglia
Glia
51
4 types of glia in the brain
Astrocytes
Microglia
Oligodendrocytes
Radial glia
52
synchronize the activity of the axon by wrapping around the presynaptic terminal and taking up
chemicals released by the axon
Astrocytes
53
remove waste material and other microorganisms that could prove harmful to the neuron
Microglia
54
What builds the myelin sheath that surrounds and insulates certain vertebrate axons?
Oligodendrocytes (in the brain and spinal cord) and Schwann cells (in the periphery of the body)
55
What guides the migration of neurons and the growth of their axons and dendrites during embryonic development?
Radial glia
56
When embryonic development finishes what do most radial glia differentiate into ?
neurons and a smaller number differentiate into astrocytes and oligodendrocytes
57
\_\_\_\_\_ are responsible for myelination, the “white matter” in the brain.
Ogliodendrocytes
& Schwann cells
58
Most of a neuron’s membrane is phospholipid molecules, but it also contains:
Protein molecules
59
The nerve impulse travels away from the cell body along the:
Axon
60
What is the mechanism that surrounds the brain and blocks most chemicals from entering?
The blood-brain barrier
61
What destroys damaged or infected cells throughout the body?
The immune system
62
What is the importance of the blood-brain barrier?
Since neurons in the brain generally do not regenerate, it is vitally important that the blood brain barrier to block incoming viruses, bacteria, or other harmful material from entering
63
Where are thicker endothelial cells in capillaries located?
brain
64
More work to move nutrients from blood to brain.
True or False?
True
65
What energy sources facilitates the process that expends energy to pump chemicals from the blood into the brain?
Active transport is the protein-mediated process
66
What is brought into the brain via active transport?
Glucose, certain hormones, amino acids, and a few vitamins
67
What makes it difficult for chemotherapy to pass through the brain?
The blood-brain barrier
68
What tpe of neuron depends almost enirely on glucose?
Vertebrate neurons
69
What is one of the few few nutrients that can pass through the blood-brain barrier?
sugar
70
Neurons need a steady supply of oxygen. True or False?
True
## Footnote
20% of all oxygen consumed by the body is used by the brain
71
Which vitamin does the body need to use glucose?
Thiamine
72
What caues Korsakoff’s syndrome? What are the symptoms?
Prolonged Thiamine deficiency from chronic alcoholism
marked by severe memory impairment
73
Chemical communication between neurons is accomplished by:
Neurotransmitters
74
Two types of cells are able to communicate through neurotransmitters.
Neurons
Astrocytes
75
What is an electrical message that is transmitted down the axon of a neuron?
Nerve impulse
76
The impulse does not travel directly down the axon but is regenerated at points along the axon so that it is not weakened. True or False?
True
77
What is the range of speed for nerve impulses?
ranges from less than 1 meter/second to 100 meters/second
A touch on the shoulder reaches the brain more quickly than a touch on the foot
78
The brain is unable to register small differences in the time of arrival of touch messages. True of False?
True
79
The properties of impulse control are well adapted to the exact needs for information transfer in the nervous system. True of False? Give an example.
True
## Footnote
Consider vision, where movements must be detected as accurately as possible
80
What is polarization?
membraneofa neuron maintains an electrical gradient. A difference in the electrical charge inside and outside of the cell.
81
What is the state of the neuron prior to the sending of a nerve impulse?
resting potential
82
At rest, the membrane maintains an electrical polarization or a difference in the electrical charge of \_\_\_locations • The inside of the membrane is slightly \_\_\_with respect to the outside (approximately ___ millivolts)
two
negative
70
83
The membrane is \_\_\_\_\_\_\_, allowing some chemicals to pass more freely than others
selectively permeable
84
What passes through pass channels in the nueural membrane?
Sodium, potassium, calcium, and chloride
85
When the membrane is at rest:
\_\_\_\_\_\_are closed
\_\_\_\_are partially closed allowing the slow
passage of \_\_\_\_
Sodium channels
Potassium channels
potassium
86
The\_\_\_\_\_\_ pump is a protein complex that continually pumps three \_\_\_\_out of the cells while drawing two \_\_\_\_into the cell which helps to maintain the \_\_\_\_\_
sodium-potassium
sodium ions
potassium ions
electrical gradient
87
The ______ and the concentration gradient (the difference in distributions of ions) work to pull \_\_\_\_ions into the cell
electrical gradient
sodium
88
The electrical gradient tends to pull \_\_\_\_into the cells, but they slowly leak out, carrying a\_\_\_\_ charge with them
potassium ions
positive
89
The charge inside the neuron is usually more _____ than outside the neuron.
negative
90
The sodium-potassium pump removes ____ Na+ ions for every _____ K+ ions
3:2
91
When the neuron membrane is at rest, sodium channels are _____ and potassium channels are \_\_\_\_\_.
Closed; partially closed
92
The resting potential remains stable until the neuron is stimulated
True or False?
93
\_\_\_\_\_\_refers to increasing the polarization or the difference between the electrical charge of two places
Hyperpolarization
94
\_\_\_\_\_\_\_\_\_\_refers to decreasing the polarization towards zero
Depolarization
95
\_\_\_\_\_ refers to a level above which any stimulation produces a massive depolarization
The threshold of excitement
96
\_\_\_\_\_\_is a rapid depolarization of the neuron
An action potential
97
The action potential threshold \_\_\_\_\_from one neuron to another
varies
98
Stimulation of the neuron past ________ triggers a nerve impulse or action potential
the threshold of excitation
99
\_\_\_\_\_\_\_\_\_\_are membrane channels whose permeability depends upon the voltage difference across the membrane
Voltage-activated channels
100
\_\_\_\_\_and \_\_\_\_\_\_are voltage activated
channels
Sodium
potassium channels
101
When sodium channels are opened, \_\_\_\_\_charged sodium ions rush in and a subsequent nerve impulse occurs
positively
102
After an action potential occurs, sodium channels are quickly\_\_\_\_\_\_. The neuron is returned to its \_\_\_\_\_\_by the opening of potassium channels.\_\_\_\_\_\_ flow out due to the \_\_\_\_\_and take with them their positive charge. The \_\_\_\_\_later restores the original distribution of ions
closed
resting state
Potassium ions
concentration gradient
sodium-potassium pump
103
The process of restoring the sodium-potassium pumpto its original distribution of ions takes time. True or False?
True
104
An unusually rapid series of action potentials can lead to a build up of \_\_\_\_within the axon. Can be \_\_\_to a cell, but it only occurs in \_\_\_\_instances
such as \_\_\_\_and after the use of certain drugs.
sodium
toxic
rare
stroke
105
Local anesthetic drugs block \_\_\_\_\_and therefore prevent \_\_\_\_\_from occurring
Example:\_\_\_\_\_ and\_\_\_\_\_
sodium channels
action potentials
Novocain
Xylocaine
106
Once an \_\_\_\_\_starts, it can back-propagate into the cell body and \_\_\_\_\_\_, causing the \_\_\_\_\_\_to be more susceptible to structural changes responsible for learning
action potential
dendrites
dendrites
107
The \_\_\_\_\_\_\_\_states that the amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it. Action potentials are equal in \_\_\_\_\_and \_\_\_\_\_within a given neuron.
all-or-none law
intensity
speed
108
Action potentials vary from one neuron to another in terms of \_\_\_\_, \_\_\_\_\_\_, and \_\_\_\_\_.
amplitude
velocity
shape
109
Studies of mammalian axons show that there is much variation in the types of \_\_\_\_\_and therefore in the characteristics of the action potentials
protein channels
110
After an action potential, a neuron has a \_\_\_\_\_\_during which time the neuron resists the production of another action potential
refractory period
111
The \_\_\_\_\_\_\_is the first part of the period in which the membrane cannot produce an action potential
absolute refractory period
112
The _________ is the second part in which it takes a stronger than usual stimulus to trigger an action potential
relativere fractory period
113
Powerful toxin named after the four- toothed puffer fish family
Tetrodotoxin
114
Famous also as the occasionally deadly raw fish delicacy fugu in Japan. Also found in the \_\_\_\_\_Acts on \_\_\_\_\_\_, can kill quickly through complete disruption of \_\_\_\_\_. Other poisons work on disrupting _____ by disrupting \_\_\_\_or neurotransmitter communication
blue ringed octopus.
sodium channels
neuron firing
neural communication
calcium channels
115
In a motor neuron, the \_\_\_\_\_\_begins at the \_\_\_\_\_\_(a swelling where the axon exits the soma) Propagation of the action potential is the term used to describe the transmission of the action potential down the \_\_\_\_\_. The \_\_\_\_\_does not directly travel down the axon
action potential
axon hillock
axon
action potential
116
The myelin sheath of axons are interrupted by short unmyelinated sections called \_\_\_\_\_\_\_\_
nodes of Ranvier
117
Myelin is an insulating material composed of \_\_\_\_and\_\_\_\_.
fats
proteins
118
At each node of Ranvier, the action potential is regenerated by a chain of \_\_\_\_charged ion pushed along by the previous segment
positively
119
Saltatory conduction: used to describe the \_\_\_\_\_of the action potential from node to node. Provides rapid conduction of \_\_\_\_\_\_\_. Conserves \_\_\_\_\_for the cell
“jumping”
impulses
energy
120
Disease in which the myelin sheath is destroyed and associated with poor muscle coordination and sometimes visual impairments
Multiple sclerosis
121
Not all neurons have lengthy axons. True or False?
True
122
Local neurons have \_\_\_\_axons, exchange information with only close neighbors, and do not produce\_\_\_\_\_
short
action potentials
123
When stimulated, local neurons produce graded potentials, which are _____ that vary in magnitude and do not follow the all-or-none law
membrane potentials
124
A local \_\_\_\_depolarizes or hyperpolarizes in proportion to the\_\_\_\_\_\_
neuron
stimulation
125
Local neurons are difficult to study due to their\_\_\_\_\_
small size
126
Most of our knowledge has come from the studyof large neurons. True or False?
True
127
neuron
128
neuron membrane with protein channels
129
Left=most capillaries in body
Right=Brain capillary
130
Difference in voltage between inside & oustide of cell's membrane
Membrane potential
131
Electrically charged particles
ions
132
What causes the difference in voltgage in membrane potential?
ions
133
What structure prevents ions from entering or leaving?
protein membrane
134
Concentration of sodium ions is \_\_\_\_on the outside, while the concentration of potassium ions is \_\_\_on the inside, in it's resting state, a neuron's resting potential is around ___ minivolts
greater
greater
70
135
At resting potential, the neuron is said to be \_\_\_\_.
polarized
136
When a neuron is polarized, it's ion channels are \_\_\_\_
closed
137
Protein structures in the membrane that allow that allow ions to flow in or out of the cell
ion channels
138
When ion channels are closed, only a few only a few\_\_\_\_pass through the \_\_\_\_to the inside and only a few \_\_\_\_pass through \_\_\_\_\_to the outside.
sodium ions
sodium channel
potassium ions
potassium channel
139
When a neuron is stimulated as a result of \_\_\_\_\_\_, the membrane potential becomes slightly more positive. In other words, it partically \_\_\_\_. If this \_\_\_\_reaches the neuron's \_\_\_\_\_which is a point about 10 minivolts more positive than negative, the neuron will initiate \_\_\_\_\_by completely depolarizing the membrane.
neurotransmission
de-polarizes
depolarization
threshold
action potential
140
During complete depolarization, sodium channels ___ and sodium ions rush\_\_\_.
open
in
141
As a result of depolarization, the inside of the membrane briefly becomes more \_\_\_\_than the outside. This spike is the \_\_\_\_\_. The sodium channels then \_\_\_\_.
positive
action potential
close
142
When the potasium channels are open, repelled by the \_\_\_\_charge inside some of the potassium ions move through the open potassium channels to the \_\_\_\_.
positive
outside
143
During the \_\_\_\_\_phase, the outward movement of potassium ions begins to return to the membrane's potential to normal. The potassium channels \_\_\_\_.
repolarization
close
144
Before the membrane potential stabilizes again at about \_\_\_, there is a small \_\_\_\_\_in the membrane potenial. During this refractory period, the neuron \_\_\_\_fire another action potential.
70 minivolts
undershoot
cannot
145
When the membrane potential returns to its resting state, the excess\_\_\_\_ and \_\_\_\_slowly diffuse away from the membrane. The neuron is now ready to fire another action potential. Once fire, an action potential quickly spreads along the membrane of the axon like a wave through the process of \_\_\_\_\_until it reaches its \_\_\_\_. Via\_\_\_\_\_with other neurons, axon terminals is where\_\_\_\_\_\_\_chemical neurotransmission begins.
sodium ions
potassium ions
conduction
axon terminals
synapses
146
action potential phases
Falling phase (repolarization)
Undershoot phase (hyperpolarization)
Resting potential phase (polarization)
stimulus phase (partial de-polarization)
Rising phase (full depolarization)
147
Membrane potential generated by chemical and electrical synapses function as neuron's \_\_\_\_
input
148
If a neurotransmitter is like a telephone, a hormone is like a radio signal. True or False?
True
149
Chemically, nicotine resembles serotonin.
True or False?
False
150
Sodium releases neurotransmitters from the terminals and into the synaptic cleft. True or False?
False
151
Although once controversial, the idea of inhibitory potential is crucial to neuroscience. True or False?
True
152
Based on his experiments with dogs, Sherrington inferred that communication at synapses slowed the speed of conduction through a reflex arc.
True orFalse?
True
153
Circuit from sensory neuron to muscle response is called a \_\_\_\_\_.
reflex arc
154
What evidence led Sherrington to conclude that transmission at a synapse is different from transmission along an axon?
Sherrington found that the velocity of conduction through a reflex arc was slower than the velocity of an action potential along an axon. Therefore, some delay must occur at the junction between one neuron and the next.
155
Repeated stimuli within a brief time have a cumulative effect
temporal summation
156
The neuron that delivers transmission is the ___ neuron
presynaptic
157
Neuron that receives transimission is the ____ neuron.
postsynaptic
158
Action potentials are always depolarizations. True or False?
True
159
Graded potentials may be either \_\_\_\_\_\_(excitatory) or \_\_\_\_\_\_(inhibitory).
depolarizations
hyperpolarizations
160
A graded depolarization is known as \_\_\_\_\_\_\_\_\_. It results from a flow of \_\_\_\_\_into the neuron. If an EPSP does not cause the cell to reach its threshold, the depolarization\_\_\_\_ quickly.
excitatory postsynaptic potential (EPSP)
sodium ions
decays
161
When Eccles stimulated an axon twice, he recorded two \_\_\_\_. If the delay between EPSPs was short enough, the second EPSP added to what was left of the first one, producing \_\_\_\_\_. A quick sequence of EPSPs combines to exceed the threshold and produce an \_\_\_\_.
EPSPs
temporal summation
action potential
162
What is the difference between temporal summation and spatial summation?
Temporal summation is the combined effect of quickly repeated stimulation at a single synapse. Spatial summation is the combined effect of several nearly simultaneous stimulations at several synapses onto one neuron.
163
What was Sherrington’s evidence for inhibition in the nervous system?
Sherrington found that a reflex that stimulates a flexor muscle prevents contraction of the extensor muscles of the same limb. He therefore inferred that an interneuron that excited motor neurons connected to the flexor muscle also inhibited the input to the extensor muscle.
164
What ion gates in the membrane open during an EPSP? What gates open during an IPSP?
During an EPSP, sodium gates open. During an IPSP, potassium or chloride gates open.
165
Can an inhibitory message flow along an axon?
No. Only action potentials propagate along an axon. Inhibitory messages—IPSPs—decay over time and distance.
166
