Flashcards in Transmission Deck (84)
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1
Presynaptic modulation
One neuron/synapse can alter the synaptic strength (membrane potential) or another synapse
Excitatory or inhibitory
2
Synaptic convergence
many synaptic terminals can synapse on a single cell
3
Synthesis of a NT occurs where
in terminal or cell body
4
chemical synapse
Uses neurotransmitter
Membranes NOT connected
Synaptic cleft
5
What are the 4 biochemical steps in synaptic transmission?
1. synthesis
2. storage and release
3. binding
4. removal
6
Which type of synapse has cytoplasmic continuity
electrical
7
Potentiation synaptic pasticity
Post synaptic potential becomes greater
Greater amounts of NT released
8
Spider toxin
blocks voltage gated Ca channels
9
What is the direction of transmission for chemical synapses?
1D
10
Axodendritic synapse
Axon synapses on a dendrite
11
distance between cell membranes in electrical synapses
2-4 nm
12
Where is acetylcholine made
terminal
13
Lingand gated ion channels employ what kind of receptor?
ionotropic
14
Where are synapses located?
Dendrites
Axons
Cell bodies
15
What is the synaptic delay in chemical synapses
Fast - .3 ms
slow - several ms
16
Synaptic divergence
One synaptic terminal can make contact with multiple post synaptic cells
17
What are the 3 methods of removal of NTs from a synapse after it's been released into the cleft?
1. diffusion
2. reuptake into presynaptic cell via transporters
3. enzymatic degradation
18
Ionotropic receptors
Direct coupling between NT and ion channel - receptor on the ion channel
NT binds and causes conformational change
FAST synaptic transmission
19
electrical synapse
Direct coupling between the two membranes - physically connected via ion channels
Direct passing of ionic current
20
How is acetylcholine synthesized
in terminal
Choline + acetyl CoA
Enzyme: cholineacetyltransferase
21
What is the synaptic delay in electrical synapses
none
22
Excitatory post synaptic potential
Depolarization - voltage increases
23
Multiple action potentials cause the release of NT from _____
large dense core vesicles
24
inhibitory post synaptic potentials
hyperpolarization - voltage decreases
25
What are the steps in G protein activation
1. Rest - no NT bound, binds GDP
2. NT binds to its receptor = conformational change in G protein
3. GDP replaced by GTP
26
Where in the synaptic cleft do vesicles release their contents?
active zone
27
Where do we find acetylcholine in the body?
muscles
28
Which kind of vesicles are associated with slow synaptic transmission?
Large dense core vesicles
29
Scorpion toxin
Blocks Na channels
30
What provides energy to G protein so it can move around to the interior of the cell
GTP
31
Quantal release
All-or-none release of NT from a vesicle
32
Tetrodotoxin (TXX)
Blocks voltage gated Na channels
Can't have action potential
33
G protein (Guanine Nucleotide Binding Protein)
Heterotrimer - 3 subunits (alpha, beta, gamma)
20+ types
alpha subunit contains guanine nucleotide binding site
34
What specific channels are mediated by activation of metabotropic receptors?
1. opening/closing voltage gated ion channels when membrane potential at rest (K channels)
2. voltage gated Ca channels
3. ligand gated ion channels - increase the time the channel is open/closed
35
distance between cell membranes in a chemical synapse
30-50 nm
36
Synaptic transmission
transfer of information from one neuron to another cell
Changes in membrane potential
37
Alpha-bungarotoxin
Snakes
Blocks nicotinic acetylcholine receptors
38
What kind of cell-to-cell connection is used in an electrical synapse?
Gap junction
39
What are the 4 criteria for a neurotransmitter?
1. made in neuron from which it is released
2. present in presynaptic terminal
3. exogenous application (natural effect - if NT is applied artificially it yeilds the same result)
4. mechanism for removal of NT
40
synaptic efficacy can be changed by other synapses via
pre synaptic facilication
pre synaptic inhibition
41
All G proteins share a common mechanism for ___
activation
42
Describe the steps of the synaptic transmission process in a chemical synapse
1. Action potential changes the membrane potential of the pre-synaptic neuron
2. Ca channels open
3. Ca influx into pre-synaptic cell
4. Vesicles move to membrane and release NT into cleft
5. NT bind to post-synaptic receptors
6. Changes membrane potential of post synaptic neuron
43
Effect of morphine
Blocks voltage gated Ca channels = decrease NT release = less excitability of post synaptic cell
44
Metabotropic receptors
G protein coupled receptors
Slow transmission
Large dense core vesicles
7 subunits
45
How is acetylcholine removed from the synaptic cleft after release? products?
Enzymatic degradation via cholinesterase
Products: choline, acetic acid
46
Temporal summation
summate over time
47
Large dense core vesicles
Contain NT that is synthesized in the cell body
Slow synaptic transmission
48
Gary's type I synapse
Excitatory
WIDE synaptic cleft (>30 nm)
49
What is the difference in permeability between ligand gated and voltage gated ion channels
Voltage - allow one type of ion to pass
Ligand gated - permeable to all
50
Inhibitory synapses have ligand gated ion channels that bind ______ and are permeable to ______
GABA, glycine
Cl
51
Synaptic cleft
The space between the two membranes of a chemical synapse
52
Metabotropic receptors
Indirect coupling between receptor and ion channel (G protein coupled receptor)
SLOW synaptic transmission
53
What are the 2 kinds of post synaptic potentials?
exitatory
inhibitory
54
What is the difference in regenerative capacity between ligand gated and voltage gated ion channels? (how are more channels activated)
Voltage - change in membrane potential
ligand gated - requires more NT
55
Post-synaptic potentials
changes in membrane potential
56
What kind of vesicle is associated with fast synaptic transmission?
small synaptic vesicles
57
Ligand gated ion channels
Ionotropic receptors - fast synaptic transmission
Binds NT in small synaptic vesicles
5 subunits
58
Receptors
component of the neuron (protein) that binds the NT and results in change in membrane potential
59
Quanta
amount of transmitter in one synaptic vesicle
60
Which is the most critical step of a chemical synapse transmission?
Ca moving into presynaptic terminal
61
synapse
specialized structure for the transfer of information
62
Can a cell recieve excitatory and inhibitory post synaptic potentials?
Yes - summate together for a net change in membrane potential
63
Conotoxins
Cone snails
Blocks acetylcholine (nicotinic) receptors in periphery
Causes paralysis
Can block Na, Ca, K channels
64
Depression synaptic plasticity
post synaptic potential weakens
Reduce amount of NT released
65
What are the 2 kinds of synaptic vesicles in chemical synapses?
small
large dense core
66
Which NT is released at a neuromusclular junction?
acetylcholine
67
A single action potential causes the release of NT from _____
small synaptic vesicles
68
Presynaptic inhibition on a specific terminal results in...
little IPSP across neuron except in specific terminal
Diminishes effect of only some excitatory synapses
69
What are the 2 methods that synapses can change their own efficacy? (synaptic plasticity)
potentiation
depression
70
What are they 2 types of synapse
electrical
chemical
71
Lambert Eaton Myasthenia Syndrome
Disorder of neuromuscular jxn
Muscle weakness
Autoimmune
Antibodies are made for voltage gated calcium channels - blocks entry of Ca into presynaptic neuron
72
Myasthenia gravis
neuromuscular jxn disorder
autoimmune
Antibodies made against acetylcholine receptors (nicotinic receptors)
73
Excitatory synapses have ligand gated ion channels that bind ______ and are permeable to _____
Acetylcholine, glutamate
Na, K, Ca
74
Neurotransmitter
small molecule released from the presynaptic membrane and interacts with receptors on post synaptic membrane triggering a change in membrane potential
75
Function of metabotropic receptors
Link NT receptors to effect molecules (enzymes)
Inside the cell - causes changes in ion channel activity - leading to changed in membrane potential
76
Gary's type II synapse
Inhibitory
Smaller cleft (<30 nm)
77
Flow of signals in electrical synapses are ______
bidirectional
78
In a standard inhibitory synapse, the inhibition occurs at the cell body. This causes...
Inhibitory PSP in all post synaptic neurons (in cell with multiple axons)
Diminishes the effect of all excitatory synapses on same neuron
79
axosomatic synapse
axon synapses on cell body (soma)
80
Small synaptic vesicles
Contain NT that is synthesized in the terminal
Used for fast synaptic transmission
81
Botulism toxin
Disorder of neuromuscular jxn
Toxin gets into terminal and interferes with proteins involved in the docking of vesicles
82
spatial summation
summate over entire cell
83
axoaxonic synapse
Axon synapses on another axon
84
