Synaptic Transmission Flashcards
Synapses are ___ zones of contact which one neuron communicates with ___
Specialized
Other neuron effector cells in muscle
The average neuron forms ___ connection and receives ___ inputs
1000 synaptic
10,000
2 types of synapses:
Electrical
Chemical
Electrical synapses have __ junction which are typically ___ and ___ nM
Gap
3.5nM
20nM
Electrical synapse ions are paired ____ which bridge the continuous ___ of 2 neurons
Hemichannels
Cytoplasm
The flow of electrical synapses is __directional through a larger (___) pore
Bi
1.5nM
Each hemichannel is is called a ___ and made of 6 ___
Connexon
Connexins
Connexins open by turning:
Clockwise
The postsynaptic response follows presynaptic stimulation how fast?
Fraction of a millisecond
Benefits of electrical synapses: 1) Extremely ____ transmission 2)Connect large numbers of ___ 3)___ resistance 4) may transmit ___ signals
1- rapid signal
2- neurons
3- Low
4- metabolic
Connection of a large number of cells allows ___ cells to act and ____ as ____ cell
Small
Coordinate
One large
Low resistance of electrical synapses allows lower ____ produced and makes it (easy/difficult) to reach threshold and fire action potentials?
Depolarization
Difficult
Metabolic signals include moderate sized organic compounds such as___,___,___
Moderate sized Messenger
IP3
cAMP
Small peptides
Which X-chromosome linked disease causes demyelinization and is a single mutation of connexin 32 (CX32) in Schwann cells?
Charcot-Marie-Tooth disease
Charcot-Marie-Tooth disease affects ___ because it is an ___-linked gene mutation which affects which connexin in the Schwann cell
Males
X-linked
CX 32
CX32 is a ___ channels in the Schwann cell
Gap-junction
The synaptic cleft of a chemical synapses is ___nM and is most common between ___
20-40 nM
Neurons
Chemical synaptic delay is at least ___ms, usually ___ms or longer
0.5 ms
1-5 ms
Chemical synapses fire (uni/bi)-directionally?
Unidirectional
Chemical synapse: ___ opens the presynaptic nerve terminals, which releases ___. This opens the receptor on the post synaptic cell allowing ___ to fire an action potential
Ca+
Neurotransmitter
Na+
T/F Chemical synapses rely on the receptor to determine the reaction.
FALSE It’s not about the receptor, it is about the (neuro)transmitter
Inhibitory neurotransmitters ___polarize the postsynaptic membrane
Hyperpolarize
Excitatory neurtransmitters ___polarize the postsynaptic membrane
Depolarize
Chemical synapses:
AP in presynaptic cell causes ___ of ___ terminal
Depolarization
Presynaptic
Voltage gated Ca+ channels open allowing ___ to enter ___ terminal. This causes the release of ___ into synaptic cleft
Ca+
Presynaptic
Neurotransmitter
Neurotransmitter diffuses across ___ and combines with receptors on ____ membrane
Synaptic cleft
Post synaptic membrane
___ transmitters hyperpolarize postsynaptic membrane
Inhibitory
Inhibitory neurotransmitters ___ postsynaptic membrane
Hyperpolarize
____ neurotransmitters depolarize postsynaptic membrane
Excitatory
Excitatory neurotransmitters ___ postsynaptic membrane
Depolarize
Neurotransmitters act either ___ or ___
Directly
Indirectly
Neurotransmitters act either directly or indirectly and their action is mediated by:
Receptors
2 classes of chemical receptors
Ionotropic
Metabotropic
Ionotropic receptors gate ions ___
Directly
Metabotropioc receptors gate ions ___
Indirectly
Nicotinic ACh receptor at NMJ is a ___ channel which has 2 subunits
Ionotropic (direct effect)
Ionotropic channel is formed by ___ domain which forms the ___ for neurotransmitter
Extracellular domain
Receptor
Ionotropic channels have ___ spanning domain which forms ___ channel
Membrane
Ion
3 effects of ionotropic channels 1)____ 2) effects last ___ 3)___ behavior
Fast
Milliseconds
Rapid
Examples of metabotropic receptors:
Norepinephrine
Serotonin
Metabotropic receptors are: 1)___ 2) effects last ___ to ___ 3) reinforce pathways in the process of ___
Slow
Seconds to minutes
Process of learning
The somatic motor neuron has ___ dendritic cells by___
Myelinated
Schwann cells
Somatic motor neurons have NMJ with presynaptic/ post synaptic clefts ranging between ___ and ___ nM
20
100
The neurotransmitter for NMJ is :
ACh
NMJs motor end plate with junctional folds of the ___
Sarcolema
Nicotinic ACh binding site receptors operate the ion channel for ___ & ___
Na
K
NMJ presynaptic terminals with synaptic vesicles are an ___ zone and are very ____
Active
Dense
Enzyme which couples ACh from Actely CoA and cholin in presynaptic terminal
Choline acetlytransferase
ACh is stored with __ and ___ for later use
ATP
Proteoglycan
2 molecules of ___ are needed to activate 1 ___ channel
ACh
Nicotinic
ACh/ Nicotinic channels allow ____& ___ to pass through
Na
K
Nicotinic transmembranes consist of ___ subunits and ___ helixes. Each M2 segment may be important for channel gating and ion permeation
5
M2
In the end plate potential, postsynaptic membrane is ___ to a values 1/2 way between ___ and ___ equilibrium. approx ___ mV
Depolarized
Na
K
0
The content of one synaptic vesicle is known as one ___
Quantum
One quantum produces ___ plate potential
Miniature end
MEPP is the ___ possible EPP
(Miniature end plate potential)
Smallest (End plate potential)
NMJs are always ___, not inhibitory
Excitatory
___ breaks down ACh within ___ of being released
Acetylcholinesterase
1 msec
AChE breaks ___ into ___ and ___ to be recycled by choline/ acetyl transferase one the presynaptic nerve
Acetylcholine
Acetate
Choline
NMJ is so vital to like that everything is done in ___
EXCESS
The excess of NMJ includes:
excess ____ release
Excess number of ___ and
Excessive ____ potential to ensure transmission of stimulus and ____ muscle contraction
Neuro transmitter
Receptors
Post-synaptic
Smooth
One neuron (DOES/ DOES NOT) excite another neuron…you need ___ of multiple neurons to fire AP
Does NOT
Summation
Myasthenia gravies affects the ___ motor system hallmarked by ___ weakness and fatigue resulting from __ number of___ receptors on muscle end plate
Somatic
Muscle weakness
Reduced
ACh
Treatment of myasthenia gravis is with ___ inhibitors. This prolongs the action of ___ at muscle end plates
AChE
ACh
____ blocks release of ACh from presynaptic terminals. At the NMJ this is a ___ blockade
Botulinum toxin
Total
___ competes with ACh for receptors on motor end plate ___ size of the (EPP; End plate potential). Maximal doses produce ___ of respiratory muscles and ___
Curare
Decreases
Paralysis
Death
___ inhibits AChE Prolongs/enhances action of ___ and muscle end plate
Neostigmine
ACh
____ blocks the re-uptake of ___ into the presynaptic terminal At the NMJ, this ___ stores of ___ from the presynaptic terminal
Hemicholinium
ACh
Depletes
ACh
