Neurons and Nervous Systems Flashcards
2
Q
What’s wrong with using hormones to communicate over long distances?
A
Slow signals, limited by receptors and also slow diffusion
3
Q
Neurons are excitable, what does that mean?
A
It can generate and propagate electrical signals (aka nerve impulses/action potentials)
4
Q
What are neurons?
A
Specialized cells of the nervous system that receive, encode, and transmit info (RET)
5
Q
Support cells of neurons
A
Glial cells
6
Q
What makes up nervous systems?
A
Neurons with their glial cells
7
Q
Information is received by ______
A
Sensory cells
8
Q
Another word for conversion into electrical signals
A
Transduced
9
Q
Information is _____ into ___ that are transmitted and processed by _____.
A
Transduced into electrical signalsNeurons
10
Q
To cause _____ or ____ responses, a nervous system communicates the electricalSignals to ____
A
Behavioral and physiologicalEffectors
11
Q
What are effectors?
A
Muscles and glands that receive electrical signals
12
Q
The simplest neural network consists of how many cells?
A
3
13
Q
What are the three cells that make up the simplest neural network?
A
Sensory neuron connected to a motor neuron connected to a muscle cell
14
Q
What connects sensory neurons to a motor neuron?
A
Interneurons
15
Q
Neurons and synapses are divided into ______ that function in _____
A
Networks that function in parallel
16
Q
A network of neurons areas also called a
A
Nerve net
17
Q
Nerve nets (aka _____) provides _______ from sensory cells to effectors
A
Neuron networkDirect lines of communication
18
Q
Nerve nets provide ____ lines of communication from ____ to ___
A
DirectSensory to effectors
19
Q
What is a ganglia?
A
A cluster of neurons
20
Q
When pair of ganglia are larger and more central, they call it the
A
Brain
21
Q
CNS is
A
The Central Nervous System
22
Q
The spinal cord and the brain make up the
A
Central nervous system
23
Q
In vertebrates most of the cells of the nervous system are found in
A
The brain and spinal cord
24
Q
Describe the generic pathway of information traveling through the nervous system (hint: start with sensory cells)
A
Sensory cells ➡ CNS ➡ effectors
25
Q
CNS sends signals to effectors via
A
Neurons
26
The CNS sends signals to effectors via neurons what reside/extend
Outside the brain and spinal cord
27
Neurons and supporting cells found outside the CNS are called the
Peripheral nervous system
28
PNS
Peripheral nervous system
29
Parts of a neuron
Dendrites, cell body, axon hillock, axon, axon terminals
30
Dendrites
Projections from the cell body that bring info from other neurons and sensory cells to the cell body
31
Cell body
Contains the nucleus and most of the neuron's organelles. The "house"
32
Axon
Carries info away from the cell body.Conduct info to target cells, the "road" to the other cell
33
Axon hillock
Integrates info collected by dendrites and initiates action potentials. the "driveway" between the house and the road
34
Axon terminal
Fine nerve endings of an axon positioned very close to the target cell that release neurotransmitters. "the parking spot"
35
Neurotransmitters
Chemical messengers
36
Neurons function differently in all animals
False
37
Variation between different types of neurons exist
True
38
Axon lengths differ
True
39
Synapse
A region where nerve impulses are transmitted and receivedEncompasses axon terminalPermits a neuron to pass an electrical/chemical signal-can learn and remember
40
Neurons transmit signals across the
Synapse
41
Microelectrodes can measure the
Membrane potential
42
Membrane potential
The difference in voltage across the plasma membrane of a neuron
43
The voltage difference of an _____ neuron is called the _______
UnstimulatedResting potential
44
The resting membrane potential is
-60 mV
45
The inside of the call is more positive than the outside
False
46
Electrical charges move across cell membranes as
Charged ions
47
The major ions that carry electric charges across the plasma membranes
Sodium (Na+)Chloride (Cl-)Potassium (K+)Calcium (Ca2+)
48
Extracellular area has a high concentration of what ion?
Sodium (Na)
49
Intracellular area has high concentration of
Potassium (K)
50
What generates a constant concentration gradient of Na and K across the plasma membrane?
K/Na - ATPase
51
What uses Na/K-ATPase to pump the ions against their concentration gradient?
Ion pumps
52
The sodium potassium pump
Expels Na from the cell and exchange them for K+ ions from outside
53
Ion Channels are
Pores formed by proteins in the lipid bilayer that selectively allowIons to pass through
54
Greater concentration of K in the cell is due to
The sodium potassium pumps
55
Open channels allow K+ to
Diffuse out the cell
56
Potassium equilibrium potential
Membrane potential at which the tendency of K+ ions diffuse in and out of the cell are equal
57
Ion channels that open/close under certain conditions are called
Gated channels
58
Voltage-gated channels
Open/close in response to a change in voltage across the plasma membrane
59
Chemically gates channels
Open/close depending on the presence/absence o a specific chemical that binds to the channel protein
60
Depolarized membrane is when
The inside of a neuron becomes less negative compared to the resting condition
61
Hyperpolarized
When the inside of a neuron becomes more negative in comparison to its resting condition
62
Opening and closing of ion channels resulting from voltage changes are the basic mechs by which _____ neurons respond to stimuli
Motor
63
Nerve impulses
Action potentials that travel along axons
64
Action potential
Sudden and major change membrane potential
65
Action potentials happen fast or slow?
Very fast
66
During action potentials voltage hanged from
-60mV (resting) to +50mV
67
Channels primarily responsible for action potentials
Voltage-gates sodium channels
68
At the resting potential most of the sodium channels are _____
Closed
69
Threshold potential
The specific membrane potential where voltage-gated ion channels open
70
During the transmission of an action potential, sodium channels stay open for
less than a millisecond
71
The opening of sodium channels cause the ___ phase or _____ of the action potential
rising phase or "spike"
72
________ channels open more slowly than the voltage-gated sodium channels
Voltage-gated potassium
73
Voltage-gated potassium channels stay open shorter than sodium ones
False
74
The ability for voltage-gated K+ channels to stay open longer allows potassium ions to carry excess ______ out of the axon
Positive charges
75
Voltage-gated ______ channels causes the plasma membrane to return to its resting potential
potassium
76
Voltage-gated sodium channels can be triggered again after how long?
Only 1-2 milliseconds
77
Refractory period
the time when a plasma membrane cannot propagate an action potential
78
Action potentials can lose signal if traveling long distances
False
79
The all-or-nothing speculation of action potentials
It is an "all-or-nothing" because of the quick interaction between the VG sodium channels and the membrane potential
80
Action potentials can be reversed
Self-regenerating
81
Why can action potentials not be reversed?
the part of the membrane that it came from is in its refractory period
82
Action potentials travel faster in ______ axons
large-diameter
83
Squids have neurons with ____ axons
GIANT
84
The axons of the squid control the
water jet propulsion system
85
What did the scientists Hodgkin and Huxley use to study electrical properties of axonal membranes to discover action potentials?
Giant axons from squids
86
Patch clumping is
a research method that allows single ion channels to be studied
87
Describe the process of "patch clamping"
A recording pipette is used to clamp a patch of neuron plasma membrane and measure the voltage differences when ion channels open and close
88
In vertebrates it is impractical to _____ propagation velocity by ______axon size because of the ____ numbers of axons present
increase propagation, increasing axon size, very large
89
Axons in the CNS are myelinated by
oligodendrocytes
90
Myelin does what?
electrically insulates the axon
91
Ion channels are clustered at the
nodes of Ranvier
92
Saltatory conduction
when an action potential fires at one node of Ranvier and jumps to the next one
93
Saltatory conduction is ____ than continuous signal propagation
much faster
94
Signals travel _____ down myelinated (insulated) axons because
faster; it travels faster through the cytoplasm compared to ion channels opening and closing
95
Glial cells
physically support and orient neruons and provide insulation for axons
96
Schwann cells
a type of glial cell that wraps around the axons
97
Schwann insulate axons of neurons in the _________
PNS (peripheral nervous system)
98
Oligodentrocytes have a similar function to _____ except they do it in the _____
Schwann cells; CNS
99
Myelin
Substance of myelination (insulation) and is the covering produced by Schann cells/oligodendrocytes
100
Glial cells do what for neurons?
supply them with nutrients.
101
Gligl cells can communicate electrically through _____
Gap junctions
102
What glial cells contribute to the "blood-brain barrier"
Astrocytes
103
Blood-brain barrier
protects the brain from toxic chemicals in the blood
104
______ surround the smallest blood vessels in the brain
Astrocytes
105
Astrocyte properties
permeable to fat-soluble molecules (like alcohol)
106
Multiple Sclerosis (MS)
myelin is destroyed and affects a huge range of nervous system functions (ex: changes of sensation in body parts, cognitive impairments, unstable balance)
107
Demyelination
gradual destruction of myelin
108
MS is though to be an _____ that affects the
autoimmune disease; CNS
109
Remyelination is not possible for the body
False (however, there can be irreversible nerve damage)
110
Relapsing-Remitting MS occurs ____ of cases
85%
111
the exact cause of MS is unkown
True
112
MS is more common in woman than men suggesting that ________ may play a significant role
hormones
113
MS can also appear in what form?
outbreaks or "clusters"
114
The risk for MS increases with greater distance from the _______
Equator
115
Neuromuscular Junction
the chemical synapse between a motorn turn and a muscle cell
116
Neurotransmitters
Vesicles filled with chemical messenger molecules from synapses
117
Acetylcholine
neurotransmitter used by all vertebrate motor neurons
118
Acetylcholine is released when vesicles fuse with the _______
presynaptic membrane
119
Synaptic cleft
the narrow space where acetylcholine enters after fusing with the presynaptic membrane
120
The _______ membrane of a neuromuscular junction has ______ channels that allow ____ to pass through
postsynaptic ; acetylcholine-gated ; Na+
121
the "motor end plate" is
the postsynaptic membrane of the neuromuscular junction
122
The contraction of the muscle cell is due to
the depolarization of the motor end plate (postsynaptic membrane) when Na+ diffuses
123
How many ACH vesicles that each contain how many ACH molecules is needed to fire a muscle cell action potential?
100 vesicles, each with 10K molecules
124
Excitatory synpases
a postsynaptic neuron that response to chemical stiumlation by depolarizing
125
Inhibitory synpases
a postsynaptic neuron that hyperpolarizes
126
Common inhibitory neurotransmitters in vertebrates
GABA (gamma-amino butyric acid) and glycine
127
GABA and glycine recptors are
Gated chloride channels
128
Gated chloride channels can be both voltage and chemical gated
True
129
when chloride channels are activated, they can _____ the PS membrane and make the cell ____ likely to fire an action potential
hyperpolarize ; less likely
130
Describe the very general process that leads to an excitatory synapse (hint: 3 topics)
ACH-receptor --> Na ---> depolarization
131
Describe the very general process that leads to an inhibitory synapse (hint: 3 topics)
GABA-receptor --> Cl- --> hyperpolarization
132
Bascially excitatory is
depolarization w/ Na w/ ACH
133
Bascially inhibitory is
hyperpolarization w/ Cl w/ GABA
134
Where the neuron "decides" to fire an action potential
Axon hillock
135
Is the axon hillock myelinated or nor
NOT
136
The axon hillock has few volatge channels
FALSE
137
inputs from the synapses are conducted through the ___
Cell body
138
If the axon hillock is ______ to the ______ level, the axon fires an action potential
depolarizes the axon hillock to the threshold
139
Synapses _____ to the cell body have a _____ influence on the axon hillock
closer have greater influence
140
Closer synapses to the cell body have greater influence because potentials ______ as the spread from the synapse
decrease
141
potentials stay the at the same level no matter how far they go
False, they decrease
142
Excitatory and inhibitory are "summed"
spatially and temporally
143
Spacial summation
adds up the simultaneous influences of synapses (on different sites on the PS cell)
144
Temporal summation
adds up the PS potentials generated at the same site in a rapid sequence
145
Always relate depolarization to _____
Firing action potentials
