Lesson 3: Neuronal Communication Flashcards
1
Q
Where do neurons communicate?
A
Synapses
2
Q
What are synapses? (2)
A
Specialized junction between neurons
Allow for communication between neurons
3
Q
_________________ travel from presynapatic to postsynaptic neuron
A
Neurotransmitters(NTs)
4
Q
Synapses are either __________ or ________
A
Electrical
Chemical
5
Q
List the following about Electrical Synapses:
Direction
Speed
Distance between pre- and postsynaptic cells
Signal travel method
Signal Type
A
Bidirectional Fast 3.5 nm Ions travel directly through gap junction channels Electrical signal (ion flow)
6
Q
List the following about Chemical Synapses:
Direction
Speed
Distance between pre- and postsynaptic cells
Signal travel method
Signal Type
A
Unidirectional Slower than electrical 20 nm Ions diffuse to postsynaptic side Chemical signal (neurotransmitter)
7
Q
What is the chemical signal for chemical synapses?
A
Neurotransmitters
8
Q
What is the electrical signal for electrical synapses?
A
Ion flow
9
Q
True or False:
Chemical synapses are faster than electrical synapses
A
False, chemical synapses are slower than electrical synapses
10
Q
What is one common classification scheme for synapses?
A
Based on the neuronal structures involved
11
Q
What are the types of synapses based on the neuronal structures involved? (3)
A
Axoaxonic
Axodendritic
Axosomatic
12
Q
Chemical synapse consists of what? (2)
A
Presynaptic terminal
Postsynaptic terminal
13
Q
What are neurotransmitters?
A
Chemical messengers which are released from the presynaptic terminal into the synaptic cleft
14
Q
Neurotransmitters bind to receptors on the ____________ membrane
A
Postsynaptic
15
Q
What are the criteria of neurotransmitter molecules? (3)
A
Must be synthesized and stored in the presynaptic neuron
Must be released by presynaptic neuron upon stimulation
When applied experimentally, must produce the same effect in the postsynaptic neuron as when it is released from the presynaptic neuron
16
Q
What are the 3 categories of NTs?
A
Amino acid NTs
Monoamine NTs
Peptide NTs
17
Q
List the characteristics of amino acid and monoamine NTs (2)
A
Small molecules
Produced, stored and released from synaptic vesicles
18
Q
True or False:
Amino acid NTs are large molecules
A
False, amino acid and monoamine NTs are small molecules
19
Q
Where are amino acid and monoamine NTs produced?
A
Synaptic vesicles
20
Q
List the characteristics of peptide NTs (3)
A
Large molecules
Stored and released from secretory granules
Produced in cell body
21
Q
Where are amino acid and monoamine NTs stored and released?
A
Synaptic vesicles
22
Q
Where are peptide NTs stored and released?
A
Secretory granules
23
Q
Where are peptide NTs produced?
A
Cell body
24
Q
In Small Molecule Synthesis:
Small Molecule NTs are synthesized from _____ ____ precursors at the ________
A
Amino acid
Terminal
25
In Small Molecule Synthesis:
| Small Molecule NTs are transported in ________ locally
Vesicles
26
In Neuropeptide Synthesis:
| Precursor _______ synthesized on _____ __
Peptide
| Rough ER
27
In Neuropeptide Synthesis:
| Precursor protein split in ____ to form active _______
Golgi
| Protein
28
In Neuropeptide Synthesis:
| Secretory vesicles with _______ bud off of _____
Peptide
| Golgi
29
In Neuropeptide Synthesis:
| Secretory ________ transported to ____ ________
Granules
| Axon terminal
30
What is the presynaptic mechanism of neurotransmitter release? (5)
Vesicles docked at the membrane ready to release NTs
Action potential depolarizes the membrane
Calcium channels on the terminal open
Influx in calcium triggers vesicle fusion to membrane
NTs are released in the synaptic cleft
31
Proteins on membrane and vesicle form a _____ _______ to "dock" vesicles at the presynaptic terminal
SNARE complex
32
What destabilizes interactions within SNARE complex?
Calcium influx
33
What happens when calcium influx occurs?
Vesicle membrane and cell membrane fuse, releasing NTs into the synaptic cleft
34
What are the postsynaptic mechanisms of neurotransmitter release? (3)
NTs diffuse through the synaptic cleft
| Bind to and activate receptors on the postsynaptic neurons
35
Postsynaptic neuron receptors can be __________ or ____________
Ionotropic (ion channels)
| Metabotropic (GPCRs)
36
List the major amino acid NTs (3)
Gamma-aminobutyric acid (GABA)
Glutamate (Glu)
Glycine (Gly)
37
List the major amine NTs (6)
```
Acetylcholine (ACh)
Dopamine (DA)
Epinephrine
Histamine
Norepinephrine (NE)
Serotonin (5-HT)
```
38
List the major peptide NTs (9)
```
Cholecystokinin (CCK)
Dynorphin
Enkephalins (Enk)
N-acetylaspartylglutamate (NAAG)
Neuropeptide Y
Somatostatin
Substance P
Thyrotropin-releasing hormone
Vasoactive intestinal polypeptide (VIP)
```
39
List:
| Type and function of acetylcholine (3)
Amine NT
Controls muscle contraction
Acts at neuromuscular junction
40
List:
| Type and function of norepinephrine (3)
Amine NT
Response to novel stimuli
Sympathetic response
41
List:
| Type and function of dopamine (2)
Amine NT
| Reward and motivation
42
List:
| Type and function of serotonin (2)
Amine NT
| Appetite and mood
43
List:
| Type and function of glutamate (3)
Amino acid NT
Major excitatory NT
Excites postsynaptic neuron
44
List:
| Type and function of GABA (3)
Amino acid NT
Major inhibitory NT in CNS
Inhibits postsynaptic neuron
45
List:
| Type and function of glycine (2)
Amino acid NT
| Major inhibitory NT in PNS
46
List:
| Type and function of neuropeptide Y (2)
Peptide NT
| Contributes to appetite, nociception, and cognition
47
What is the most abundant peptide in the nervous system?
Neuropeptide Y
48
List:
| Type and function of substance P (2)
Peptide NT
| Transmits information regarding pain
49
List:
| Type and function of vasoactive intestinal peptide (VIP) (2)
Peptide NT
| Regulates blood and muscle activity in gastrointestinal tract
50
There are _ types of NT receptors, what are they?
2
Ionotropic (ion channels)
Metabotropic (GPCRs)
51
In Ionotropic Receptors:
| Ion channels open and close upon ______ binding
Ligand
52
In Ionotropic Receptors:
| Flow of ____ alters ________ _________
Ions
| Membrane potential
53
True or False:
| Ionotropic receptors are fast acting transmission
True
54
What determines opening duration of the gates linked with ionotropic receptors? (2)
Kinetics of receptor
| Gating of receptor
55
What determines the magnitude of effect in ionotropic receptors?
Conductance
56
What determines which ions enter under ionotropic receptors?
Selectivity of channels
57
Define:
| Metabotropic Receptors
Type of membrane receptor in eukaryotic cells that acts through a second messenger
58
In Metabotropic Receptors:
| Most commonly functions in ____(_) pathways and activates _ ________
GPCR (G-Protein Coupled Receptor)
| G Proteins
59
True or False:
| Metabotropic receptors can stimulate the opening of ion channels in the cell membrane
False, metabotropic receptors can stimulate or inhibit the opening of ion channels in the cell membrane
60
In G Protein Coupled Receptors:
| ______ binds to receptor
Ligand
61
In G Protein Coupled Receptors:
| Receptor activation causes a ______________ change in _-_______, and it splits
Conformational
| G-Protein
62
In G Protein Coupled Receptors:
| Subunits bind to and activate ________ proteins
Effector
63
In G Protein Coupled Receptors:
| ________ messengers are activated and __________ targets are altered
Chemical
| Downstream
64
True or False:
| G Protein Coupled Receptors have slow, but strong effects
True, these effects come via amplification
65
What is an example of GPCR signalling? List the process (7)
Epinephrine binds to receptor
Activates G-protein
Activates effector protein (adenylyl cyclase)
Production of second messenger (cAMP)
Activation of kinase (PKA)
Phosphorylation of target proteins (e.g. transcription factors)
Modification of gene expression
66
List the differences between metabotropic vs. ionotropic receptors (3)
Metabotropic
(Ionotropic)
```
Slow acting
(Fast acting)
Signal indirectly through second messengers
(Signal directly through ion channels)
Signal amplification
(No signal amplification)
```
67
What are the 3 methods for neurotransmitter clearance?
Reuptake
Degradation
Diffusion
68
```
Define:
Neurotransmitter clearance (reuptake)
```
When NTs are taken back to the axon terminal via reuptake-pumps or glial cells
69
In reuptake:
| Reabsorbed NTs are ______ for another ________________
Reused
| Neurotransmission
70
In reuptake:
| Glial cells like __________ may reuptake NTs and use for ______ or send back to the ____ ________
Astrocytes
Itself
Axon terminal
71
When NTS are taken back in reuptake, what are they taken up through? (2)
Reuptake-pumps or glial cells
72
```
Define:
Neurotransmitter clearance (degradation)
```
When NTs are broken down by enzymes at the synaptic cleft
73
True or False:
| Broken down components can't stimulate the neurotransmitter receptor
True
74
```
Define:
Neurotransmitter clearance (diffusion)
```
When NTs scatter across the synaptic cleft
75
When can diffusion for neurotransmitter clearance occur?
Can only occur during low action potential firing
76
True or False:
| Diffusion is enough to clear NTs for high action potential firing
False, diffusion won't be enough to clear NTs for high action potential firing (NTs build up in synaptic cleft)
77
Ion flow in the postsynaptic cell changes membrane potential resulting in a ____________ _________
Postsynaptic potential
78
True or False:
| Postsynaptic potentials can be excitatory
False, postsynaptic potentials can be excitatory OR inhibitory
79
What does excitatory postsynaptic potentials do?
Brings the membrane closer to threshold
80
What does inhibitory postsynaptic potentials do?
Brings the membrane away from the threshold
81
In Synaptic Integration:
| _____ can sum up in a variety of ways to lead to generation of an _______ _________
EPSPs
| Action potential
82
Define:
| Spatial summation
The addition of many EPSPs generated simultaneously at many sites
83
Define:
| Temporal summation
The addition of EPSPs generated in rapid succession
84
What is the addition of many EPSPs generated simultaneously at many sites called?
Spatial summation
85
What is the addition of EPSPs generated in rapid succession known as?
Temporal summation
86
When are electrical synapses formed?
Formed when the cytoplasm of two cells is linked by connexin channels
87
What are three characteristics of electrical synapses?
Bidirectional
Rapid
Always excitable
88
Where are electrical synapses often studied?
In the crayfish nervous system
89
In Electrical Synapses in Crayfish:
| Postsynaptic signals occur how long after the generation of a presynaptic potential?
Occur within a fraction of a millisecond
90
In Electrical Synapses in Crayfish:
| Minimal _____ allows for expedient transmission and ______ in crayfish
Delay
| Escape
91
True or False:
| Electrical synapses allow for quick motor responses in crayfish
True
92
True or False:
| Electrical synapses play a major role in synchronization of neuronal activity
True
93
In Role of Electrical Synapses:
| During development, electrical synapses provide a ________ for development of _________ networks
Framework
| Neuronal
94
In Role of Electrical Synapses:
| ___ ________ _____ also allow entrance of molecules important for intracellular signaling
Gap junction pores
95
What is the presynaptic active zone?
Specialized electron dense region of the presynaptic plasma membrane
96
What is the presynaptic active zone composed of?
Network of proteins in opposing location to postsynaptic density
97
What is the network of proteins in the presynaptic active zone responsible for?
Docking and priming of synaptic vesicles
98
In Molecular Architecture:
| Active zone is composed of _ main evolutionary proteins
5
99
What is are the 5 main evolutionary conserved proteins in the active zone?
```
ELKS
RIM
RIM-BP
Munc13
α-Liprins
```
100
State the function of ELKS
The core
101
State the function of RIM & RIM-BP
Recruiting Ca2+ channels
102
State the function of Munc13
Mediating vesicular fusion
103
State the function of α-Liprins
Providing further binding interactions
104
What is the role of the active zone? (2)
Acceleration of vesicular release
| Structural remodelling during synaptic plasticity & implication in memory formation
105
In the role of active zone:
| Neuronal communication is divided into ______ or ______ transmission
Wiring
| Volume
106
In the role of active zone:
| The presence of active zone is a determinant of the mode of _____________ between _______
Communication
| Neurons
107
List the differences between wiring transmission and volume transmission (4)
Wiring
(Volume)
Fast
(Slow, diffuse)
Precise
Energy demanding
(Less energy demanding)
Requires active zone
(Doesn't require active zone)
108
In the role of active zone:
| ____-____ ________ __________ is the induced change in ________ and ________ of synaptic transission
Long-term synaptic plasticity
Strength
Efficacy
109
List the changes at the presynapse during positive enhancement (2)
Enlargement and remodelling of active zone proteins
| Increased stability
110
List the changes at the postsynapse (1)
Increase of receptor conductance
111
In Structural Plasticity of the Active Zone:
Local neuronal activity dynamically controls ______ ____ organization through _____ dynamics to modulate presynaptic _________ and ________
Active zone
Actin
Structure
Function
112
True or False:
| Active zone matrix is polymerized
False, active zone matrix is polymerized or depolymerized depending on the level of neuronal activity leading to changes of clustering
113
In Liquid Active Zone:
| Clustering of ____ channels at ___________ active zones is critical for precise control of ________________ release
Ca2+
Presynaptic
Neurotransmitter
114
In Liquid Active Zone:
Active zone scaffold proteins ___ and ___-__ form self-assembled condensates capable of clustering _______-_____ ____ channels on lipid membrane bilayers
RIM
RIM-BP
Voltage-Gated Ca2+
115
Describe:
| Calyx of Held (2)
Neuronal terminal in the auditory system containing hundreds to thousand of active zones
Largest synapse in human body
116
```
Describe:
Neuromuscular junction (2)
```
Fixed number of active zones
| Ensuring the motor outputs to be performed upon arrival of every action potential
117
What controls vesicle docking?
Rab proteins
118
____ Complexes assemble at docked ________
| ______ pore forms and releases ________________
Fusion
Vesicles
Fusion
Neurotransmitter
119
Define:
| V-SNARE
Vesicle SNARE
| Refers to proteins located on the vesicle itself
120
Define:
| T-SNARE
Target SNARE
| Refers to proteins located on the synaptic membrane
121
What are components of SNARE complexes? (4)
Syntaxin-1
SNAP-25
Synaptobrevin
Munc-18
122
What controls calcium binding at docked vesicles?
Synaptotagmin
123
What regulate SNARE complex disassembly?
NSF Complexes
