Synaptic transmission Flashcards
The final physiologic action of a neurotransmitter is determined by the ____________
a) mechanism of termination of the physiologic effects of the neurotransmitter.
b) intrinsic properties of the receptor that binds with the transmitter.
c) intracellular 2nd messenger cascade system
d) chemical properties of the neurotransmitter.
B
What is the most important physiologic advantage of a chemical synapse have over an electrical synapse?
a) Chemical synapse can amplify signal and ensure efficient signal transmission.
b) It ensures unidirectional transmission of the action potential.
c) It has a longer lasting effect in the nervous system
d) It can mediate both excitatory and inhibitory responses.
A
Which item below does not belong to the group?
a) cAMP
b) DAG
c) G-protein
d) IP3
C
Which of the following statement(s) is/are TRUE about the role of calcium in synaptic transmission?
a) Without calcium, our nervous system would not have no outputs.
b) Neurons translate their electrical signals into action by fluxes of calcium through ligand-gated calcium channels.
c) Calcium ions serve as the generator of action potential in the presynaptic neuron
d) AOTA are true.
A
In which step of neurotransmission do calcium ions NOT play a role?
a) Mobilization of the vesicle into the active zone.
b) Docking and fusion of the vesicle with the presynaptic membrane
c) Exocytosis of the neurotransmitter
d) Reuptake of the transmitter through the transporter system
D
In another experimental set-up consisting of several interconnecting neurons, one neuronal circuit was found to be hyperexcitable. Electrical stimulation of the neuron that belonged to this circuit showed short latency and produced
prolonged depolarization. If you want to diminish or inhibit the excitability of this neuronal circuit, what type of chemical substance or drug will you apply to the system?
a) one that inhibits the voltage-gated calcium channels
b) one that blocks sodium channels
c) one that increases the potassium conductance
d) Any of the above
D
Which of the following statements is/are true of nicotinic receptors?
a) They directly gate an ion channel.
b) They produce the fast excitatory postsynaptic potentials
c) They are found in the muscle and autonomic ganglia
d) AOTA statements are true
D
Which of the following statements characterize NMDA receptors EXCEPT
a) They are ligand operated
b) They are voltage sensitive
c) Glycine removes the Mg+2 block
d) They allow sodium, potassium and calciumions to pass through.
C
Which of the following receptors are ionotropic?
a) Adrenergic receptors
b) Glycine receptors
c) Dopamine receptors
d) Opioid receptors
B
Which vitamin is a co-enzyme in the synthesis of GABA
a) Vitamin B1
b) Vitamin B6
c) Vitamin B12
d) Folic Acid
B
Which statement/s is/are ture about the fate of noradrenaline and serotonin at the synaptic cleft?
a) Both neurotransmitters utilize high affinity transporter-mediated reuptake into the presynaptic terminal
b) Both transmitters are degraded by intracellular monoamine oxidase (MAO)
c) Both neurotransmitters are degraded by catechol-O-methyltransferase (COMT)
d) AOTA statements are true
AB
In which nervous system in acetylcholine a neurotransmitter?
a) Control of movement
b) Cognition
c) Autonomic nervous system
d) AOTA
D
Which of the following neurotransmitters is/ are involved in pain modulation?
a) Serotonin
b) Glutamate
c) Opioids
d) AOTA
D
The components of the synapse include
a) Pre-synaptic membrane
b) Synaptic cleft
c) Post-synaptic membraned
d) Release of NT in the synaptic left
e) AOTA
E
Two types of synapses
Electrical and chemical synapses
Cell junction correlated with electrical synapses
Gap junction
Channels at the presynaptic neuron that let Ca into the cell
Voltage-gated calcium channels
Ions that trigger the release of neurotransmitters
Ca
At the peak of action potential, relatively little calcium enters the terminal. T/F
T
The membrane potential is positive, and the voltage gradient opposes the entry of calcium because of its positive charge
Nonpeptide neurotransmitters can fuse with the presynaptic membrane only at which specific sites?
Active zones
Proteins on the plasma membrane and vesicle membrane that bring the membranes together before fusion in the presynaptic terminal
SNARE
synaptobrevin (v-SNARE)
syntaxin and SNAP-25 (t-SNAREs)
The calcium sensors in the presynaptic terminal
Synaptotagmin
Two mechanisms of recycling vesicle membranes
Endocytotic pathway and “kiss and run”
Endocytotic pathway: coated pits form in the plasma membrane and then pinch off to form coated vesicles.
Kiss and run: the vesicle does not fuse completely with the plasma membrane, and instead detaches itself once the neurotransmitters are released
The NMDA channel is both ligand and voltage-gated. T/F
T
EPSP are always hyperpolarizing. T/F
F
They are depolarizing.
EPSPs are either depolarizing or hyperpolarizing. T/F
F
They are depolarizing only.
A hyperpolarizing potential is always an IPSP. T/F
T
An IPSP is always hyperpolarizing. T/F
F
It can be either depolarizing or hyperpolarizing
In which neuron do IPSPs and EPSPs occur?
Post-synaptic neuron
The types of summation of potentials
Spacial, temporal summation and shunting effect
Acetylcholine is synthesized from which substances?
Acetyl coenzyme A and choline
How is the action of acetylcholine terminated?
The enzyme acetylcholinesterase hydrolyzes acetylcholine into acetyl coenzyme A and choline. The Na symporter in the presynaptic membrane takes up the choline for acetylcholine resynthesis.
The major excitatory CNS neurotransmitter
Glutamate
The neurotransmitter at neuromuscular junction, at sympathetic and parasympathetic ganglia and of the postganglionic fibers from all parasympathetic ganglia and a few sympathetic ganglia
Acetylcholine
Neurotransmitter precursor to GABA
Glutamate
Although the main excitatory neurotransmitter, glutamate is a potent neurotoxin at high concentrations. T/F
T
The major inhibitory transmitter throughout the nervous system
GABA
The Purkinje cells of the cerebellar cortex contain large numbers of GABA-ergic projection neurons. T/F
T
Glycine is mainly: inhibitory or excitatory?
Inhibitory
Glycine and glutamate are co-transmitters for which receptor?
NMDA channels
How are glu and gly taken back into the presynaptic terminal?
Through Na-Cl coupled transporters
Catecholamines
Dopamine, epinephrine/adrenaline, norepinephrine/noradrenaline
Catecholamines share which amino acid precursor?
Tyr
Which catecholamines can be converted to the other?
Dopamine can be converted to norepinephrine/noradrenaline.
Norepinephrine/noradrenaline can be converted to epinephrine/adrenaline
Serotonin is derived from tyr. T/F
F
It is derived from trp
Glutamate is present in all cells. T/F
T
Glycinergic synapses are found mainly in which part of the nervous system?
Spinal cord
Noradrenergic neurons are found primarily where?
Locus coeruleus and nucleus subcoeruleus in the dorsal part of the rostral pons
Norepinephrine is important in the peripheral nervous system to which neurons?
Postganglionic sympathetic neurons
Serotoninergic fibers arise from which structures?
Raphe nuclei of the brainstem
Serotoninergic fibers are distributed throughout most of the brain and spinal cord, like noradrenergic fibers. T/F
T
Dopaminergic fibers arise from which regions?
Brainstem regions: Substantia nigra pars compacta and ventral tegmental area
Histaminergic neurons are located where?
Tuberomammillary nucleus of the hypothalamus
Classic neurotransmitters are synthesized in which part of the neuron?
Presynaptic terminal
Neuropeptides are synthesized in which part of the neuron?
Cell body
Neuropeptide receptors are not confined to the synaptic region. T/F
T
Neuropeptide action are not limited by reuptake mechanisms. T/F
T
Neuropeptides are released when there is low-frequency stimulation of the presynaptic neuron. T/F
F
They are released when there is high-frequency stimulation.
The three major classes of endogenous opioid peptides in mammals
Enkephalins, endorphins, dynorphins
Action of opioids
Inhibits brain neurons involved in pain perception
There are no specific reuptake mechanisms nor enzymatic degradation for gas neurotransmitters. T/F
T
NO is product of the oxidation of which amino acid?
Arg
Two types of acetylcholine receptors
Muscarinic and nicotinic
Two types of neurotransmitter receptors
Ionotropic and metabotropic
Receptor with an extracellular binding site for the neurotransmitter: ionotropic or metabotropic?
Ionotropic
Fast-acting receptor: ionotropic or metabotropic?
Ionotropic
G-protein coupled receptor: ionotropic or metabotropic?
Metabotropic
Slow-acting receptor: ionotropic or metabotropic?
Metabotropic
Ion channels: metabotropic or ionotropic?
Ionotropic
Nicotinic receptors: metabotropic or ionotropic?
Ionotropic
Muscarinic receptors: metabotropic or ionotropic?
Metabotropic
Glycine receptors: ionotropic or metabotropic?
Ionotropic
GABA receptors: ionotropic or metabotropic?
Both
GABA and glycine receptors have a Cl channel. T/F
T
NO and CO do not bind to receptors. T/F
T
They activate enzymes involved in second messenger cascades
Biogenic amine receptors are all metabotropic. T/F
F
There is one exception: one class of serotonin receptors
Neuropeptide receptors: ionotropic or metabotropic?
Metabotropic
An action potential arriving at the presynaptic terminal causes…
A) sodium ions to diffuse into the cell.
B) sodium ions to diffuse out of the cell.
C) calcium ions to diffuse into the cell.
D) acetylcholine to diffuse into the cell.
E) ligand-gated sodium channels to open.
C
Acetylcholine has which effect on the post-synaptic neuron?
A) Ligand gated calcium channels open and calcium diffuses in.
B) Ligand gated sodium channels open and sodium diffuses in.
C) Terminal vessels migrate to the plasma membrane.
D) Voltage gated calcium ion channels open and calcium diffuses in.
E) Voltage gated sodium ion channels open and sodium diffuses in.
B
If the post-synaptic membrane potential reaches threshold level, an action potential will be produced. T/F
T
Acetylcholine is actively transported from the pre-synaptic membrane to the post - synaptic membrane. T/F
F
