Neurotransmitters Flashcards
What amino acid and neurotransmitter is particularly important for learning and memory?
glutamate
Adrenocorticotropic hormone, prolactin, luteinizing hormone, thyrotropin, growth hormone, vasopressin, and oxytocin are all released by the _____.
pituitary gland
How are action potentials mediated?
via voltage-gated sodium (Na) channels
____ is the amino acid precursor to dopamine, norepinephrine, and epinephrine.
Tyrosine
When acetylcholine binds to the muscarinic receptor in an organ, its G-protein binds to and opens what ion channel? What happens?
K+ channel; K+ rushes out of the cell, hyperpolarizing the cell and making it less excitable (more negative than it was)
What are the steps that must happen in order to release neurotransmitters?
- stimulus must occur
- IPSP/EPSP must reach threshold potential
- voltage-gated Na+ channels open
- run down axon as an action potential
- action potential triggers voltage-gated Ca+ channels to open and allow Ca+ influx
- calcium triggers vesicles to fuse and release contents
Do ionotropic or metabotropic receptors have more immediate effects?
ionotropic (but scope is more narrow)
The influx of negative charge into the cell (e.g. Cl-) causes an _____ response.
IPSP (inhibitory)
Why are patients with Parkinson’s given supplements of L-DOPA?
because L-DOPA is a precursor to dopamine and dopamine is involved in movement
Which enzyme facilitates the synthesis of acetylcholine?
choline acetyltransferase
____ utilize activated G-proteins to diffuse into the membrane and act on ion channels*, enzymes, or gene transcription.
Metabotropic receptors
*most important
What type of synapse contains two neurons connected by a gap junction?
electrical synapse
The voltage gated Na channels open and ____ rushes into the cell, depolarizing it and causing an action potential.
Na
Where does the action potential run?
down the axon of the presynaptic neuron
Where are the voltage-gated Na+ channels located?
all along the axon (spreads down the length of it)
What are the ion concentrations of Mg2+ outside and inside the cell?
outside = 1.2 inside = 58
What are the ion concentrations of K+ outside and inside the cell?
outside = 4 inside = 140
_____ is the amount of neurotransmitter packaged into a synaptic vesicle.
Quanta
Glutamate, aspartate, and nitric oxide are _____ neurotransmitters.
excitatory
Where is the final neuronal signal sent out from (from the summation of multiple different EPSP and IPSP signals)?
axon hillock
Is atropine an agonist or antagonist to the muscarinic receptor?
antagonist (blocks channel)
Can beta-1 receptors bind both epinephrine and norepinephrine?
YES - epinephrine affinity is greater
What ion does the acetylcholine ionotropic (nicotinic) receptor facilitate the passage of through its channel?
Na+
In the nicotinic receptor, Na+ enters and excites the cell, leading to ____, and subsequent ____.
calcium release; muscle contraction
What happens when there is an influx of Ca2+ into the heart from an adrenergic response?
- Ca2+ excites the SA node, which increases heart rate
- Ca2+ accumulates in the muscle, so cardiac contractibility increases
___ is the major inhibitory neurotransmitter in the CNS, particularly in the brain.
GABA
____ synapses release neurotransmitters from the presynaptic membrane and bind to receptors on the post-synaptic membrane.
Chemical
What happens if SNAP-25 and syntaxin are cleaved?
no exocytosis can occur because fusion to the membrane cannot occur
Which neurotransmitters can be both excitatory and inhibitory?
acetylcholine
norepinephrine
Moving a cell’s charge closer to its threshold potential causes what kind of response?
EPSP (excitatory)
At rest, which ions are located extracellularly?
Na+
Ca2+
Cl-
Thyrotropin-releasing hormone, luteinizing hormone releasing hormone, and somatostatin are all released by the ____.
hypothalamus
____ is an extract that acts as an antagonist to the nicotinic receptor, blocking it.
Curare
____ is involved in movement, mood, and pleasure.
Dopamine
What are the ion concentrations of Cl- outside and inside the cell?
outside = 103 inside = 4
What happens when glutamate or glycine binds to the NMDA receptor for the glutamate Na+/Ca2+ channel?
both Ca2+ and Na+ rush into the cell (depolarizing and exciting it)
____ proteins are located in the synaptic vesicle and plasma membrane and help to dock vesicles and promote fusion of the layers for exocytosis.
SNARE
What constitutes a gap junction?
channels formed by connexons
____ is excitatory and associated with learning and memory.
Glutamate
____ open cation channels; ____ open anionic channels.
EPSP; IPSP
What does calcium activate when it enters the presynaptic cell?
synaptotagmin
Does calcium rush into or out of the cell after depolarization?
INTO
Where are nicotinic receptors located?
on muscle cell membranes
Do we have cannabinoid receptors in our brain?
YES
If the IPSPs or EPSPs are enough to reach a threshold potential, where does this occur and what happens?
trigger zone; it will open voltage-gated Na+ channels and induce an action potential
____ is mostly an inhibitory neurotransmitter and is found primarily in the spinal cord.
Glycine
Acetyl-CoA and choline are the small molecule precursors to _____.
acetylcholine
The insides of neurons have a relatively ____ charge.
negative
Anandamide and arachiodonyl glycerol are _____.
endocannabinoids
Phenylethanolamine-N-methyltransferase is an enzyme found only where in the body?
adrenal medulla
Ketamine, PCP, and methadone all ____ the NMDA receptor.
block (they are all channel blocking agonists)
____ receptors are ligand gated and when the neurotransmitter binds to the receptor it changes conformation.
Ionotropic
What proteins are associated with vesicle docking?
synaptotagmin synaptobrevin SNAP-25 syntaxin (calcium)
In influx of what substance triggers the fusion and exocytosis of the synaptic vesicles?
calcium
G-protein coupled receptors, or _____ receptors are indirectly linked to ion channels.
metabotropic
Glycine, GABA, serotonin, and dopamine are ____ neurotransmitters.
inhibitory
What is hyperpolarization?
influx of negative charge that causes the cell to become less excitable
Epinephrine is made in the ____.
adrenal medulla
What happens when you inhibit calcium influx into the presynaptic neuron?
neurotransmitter cannot be released
Which acetylcholine receptor elicits parasympathetic actions and is found IN target organs?
muscarinic receptor
Which ions have the greatest concentration outside the cell at a resting state?
Na+
Ca2+
Cl-
What must be reached by either EPSPs or IPSPs for an action potential to be triggered?
threshold potential
____ is associated with sleep and mood.
Serotonin (5-HT)
For the acetylcholine muscarinic receptor, muscarine is an _____ and atropine is an _____.
agonist (+); antagonist (-)
Why can’t memories be processed (or may even be temporarily lost) after using THC products?
because THC binding to CB1 receptors in the presynaptic neuron inhibits the influx of calcium into the cell, which prevents neurotransmitters from being released (and some of those neurotransmitters are very important for memory)
Botox inhibits the release of ____, so no muscle contraction can occur.
acetylcholine
Can proteins, peptides, or gases be neurotransmitters?
YES
Why do ions have different concentrations inside and outside the cell?
because the influx and efflux of ions via ion channels causes depolarization and excitability
The acetylcholine muscarinic receptor is found in organs, so this receptor is involved in the ____ response.
autonomic nervous system (ANS)
Where are the neurotransmitters released?
into the synaptic cleft
Why are gap junctions necessary in the heart and neurons?
because they allow depolarization to quickly happen and pass through
Enkephalins and natural opioids are ____.
endorphins
On the vesicle, synaptotagmin is activated by calcium, and then helps synaptobrevin interact with ____ and ____.
SNAP-25; syntaxin
At rest, which ions are located intracellularly?
K+
Mg+
Does acetylcholine have both metabotropic and ionotropic receptors?
YES
Do metabotropic receptors activate ion channels?
YES - indirectly via G-protein coupled receptors
How is the type of neuron and what action they will be performing determined?
the different enzymes each may contain that catalyze certain precursors
What does THC mimic in the body?
endocannabinoids
GABA is an _____ receptor and chloride channel that facilitates the influx of chloride into the cell.
ionotropic
What amino acid is serotonin derived from?
tryptophan
What type of synapse is contains a gap junction, which allows electrical current to flow directly from one cell to another?
electrical synapse
Depolarization causes cellular ____.
excitement
What type of receptor is the beta-1 adrenergic receptor? Why?
metabotropic; it is a G-protein coupled receptor
Influxing negatively charged ions into a cell via ion channels causes what response?
hyperpolarization, therefore depressing the cell or inhibiting the cell
The influx of postive charge into the cell (e.g. Na+) causes an _____ response.
EPSP (excitatory)
What channels open up after the depolarization of the presynaptic neuron?
voltage-gated Ca channels
Which ions have the greatest concentration inside the cell at a resting state?
K+
Mg+
What type of receptors are ion channels themselves (self-gated) and may depolarize or hyperpolarize the cell?
ionotropic receptors
CB1 receptors in our brain inhibit the influx of ____ into the presynaptic neuron after interacting with THC.
Ca2+
What are the ion concentrations of Ca2+ outside and inside the cell?
outside = 2.4 inside = 0.00001
____ is involved in wakefulness and alertness. in the hypothalamus.
Norepinephrine
What are the actions of medications such as propofol, barbituates, and benzodiazepines?
they increase the potentiation of the chloride channels of the GABA receptor, which further depresses the cell
What are the ion concentrations of Na+ outside and inside the cell?
outside = 142 inside = 10
What is the typical resting potential of a neuron?
-65mV
Are neurons one-on-one interactions?
NO - they have MANY, MANY different axons converging from different neurons
What is the precursor to GABA?
glutamic acid
For the acetylcholine nicotinic receptor, nicotine is an _____ and curare is an _____.
agonist (+); antagonist (-)
Transmitters are released via ____.
exocytosis
The entry of calcium and its binding to _____ triggers fusion.
synaptotagmin
Causing a cell’s charge to move away from the threshold potential causes what kind of response?
IPSP (inhibitory)
What medications bind to the GABA receptor channel?
- isoflurane
- ethanol
- propofol
- benzodiazepines
- barbituates
What is the major excitatory neurotransmitter in the central nervous system?
glutamate
What happens when norepinephrine binds to the beta-1 receptor?
it activates a G-protein, which activates adenylyl cyclase, which then activates cAMP, which activates protein kinase A, which then phosphorylates voltage-gated Ca2+ channels, which causes an influx of Ca2+ into the cell (excites cell)
What two proteins does Botox cleave?
SNAP-25
syntaxin
