Neurotransmitters and their function Flashcards
what is the most abundant neurotransmitter for inhibitory effects?
GABA
what is the most abundant neurotransmitter for excitatory effects?
Glutamate
which neurotransmitter plays a leading role in long term potentiation
Glutamate
what are the 2 primary types of neurotransmitter receptors on post synaptic neurons
inotropic and metabotropic
what functions does acetylcholine contribute to
movement, arousal, attention
when an action potential reaches the terminal buttons what chemical substance do they release
neurotransmitters
what are neurotransmitters synthesised by
Golgi apparatus
when neurotransmitters reach the synapse, where are they stored
stored in spherical packets called Synaptic Vesicles
where and how are synaptic vesicles passed
vesicles are passed down microtubules to the Pre-Synaptic Button.
what does depolarisation cause vesicles to do
Depolarisation causes vesicles to dock on presynaptic membrane using protein clusters. Need to fuse with the membrane to be released
how does depolarisation influence calcium channels
Depolarisation causes Calcium channels to open and the influx of calcium at the presynaptic terminal - calcium floods into button. This is due to concentration & electrical gradients)
what happens if calcium ions attach to the dock and what does this create
Some calcium ions attach to the dock causing the vesicle to fuse with the membrane
This creates fusion pores.
The vesicles releases the neurotransmitters into the synaptic cleft through the fusion pores.
what are receptors
Neurotransmitters have specialised receptors on the post synaptic neuron.
They travel across the synaptic cleft after being released from the pre- synaptic neuron and attach to them- thus continuing the relay of information.
what are inotropic receptors
short term acting receptors
what is ligand
Ligand is the specific chemical that activates an ionotropic receptor, also known as a ligand-gated ion channel. it causes a chemical reaction in which opens an ion channel, causing the corresponding ion to flood into the post-synaptic neuron. Influx of sodium
This effect begins quickly and doesn’t last long (~20ms)
Occurs at one point at the cell membrane.
what is a metabotropic receptor
more long lasting effects on the neuron
This, in turn, causes the activation of (ion channels or) secondary messengers which trigger intracellular signal transduction cascades.
Key survival cellular processes.
Effects are slower to activate and last longer
when neurotransmitters bind to a metabotropic, what does this activate in a cell
G proteins
why do neurotransmitters need to be removed from the synapse
they would continue exert their effects on the post-synaptic neuron.
what are antagonists
Block or decrease the action of neurotransmitters- blocks
what are agonists
Mimic or increase the action of neurotransmitters- e.g. egging it on
what can agonists and antagonists affect
receptors
degradation and reuptake
neurotransmitter release
which amino acids carry out most of the communication in the brain?
Glutamate and GABA
is glutamate IPSP OR EPSP
EPSP
is GABA IPSP or EPSP
IPSP
what is glutamate involved in
learning and memory
what happens when glutamate binds to an inotropic receptor
glutamate causes positively charged sodium (Na+) ions to flow in, depolarising the postsynaptic neuron; i.e., increasing the likelihood of an action potential.
what happens when glutamate binds to a metabotropic receptor
it triggers a cascade of intracellular events by activating a G-protein, which then leads to the production of second messengers that can modulate various cellular processes, like opening ion channels, affecting enzyme activity, and influencing synaptic transmission,
what happens if there is an over realise of glutamate
Glutamate is toxic. Over release / irregular activation is instigated in a number of mood and neurodegenerative disorders.
what happens when GABA binds to inotropic receptors
GABA causes negatively charged chloride (CL-) ions to flow in, hyperpolarising the postsynaptic neuron; i.e., decreasing the likelihood of an action potential.
what happens when GABA binds to metabotropic receptors
When binding to metabotropic receptors GABA can cause further outflux of positively charge potassium (k+) ions from the cell.
what happens if there is irregular activation of GABA
GABA has sedative effects. Irregular activation is instigated in a number of mood and neurodegenerative disorders.
what is glutamine broken down into
glutamate
what is GABA broken down into
Succinate
what is the agonist actions of alcohol
enhances and prolongs GABA functioning
what is the antagonist actions of alcohol
blocks glutamte receptors to reduce binding
what is allelopathy (plants)
Communicating with other plants and insects in order to discourage their growth, and feeding on the plant respectively.
what is pollination
Secondary metabolites provide colour and scents to attract and deter certain insects.
what is protection (plants)
Secondary metabolites are synthesized when the plant is under environmental stress e.g. UV rays and fungal/viral/pathogen attack (acting as endogenous antibiotics).
what are secondary plant metabolites
help plants defend against herbivores, pathogens, and environmental stress, attract pollinators, and facilitate competition with other plants.
how are plant compounds able to manipulate the human CNS
the human nervous system shares a lot in common with the insect CNS
what is dopamine known for
pleasure or reward system
where are the main dopaminergic receptors
mid brain
what and where is the nigrostriatal system
substantia nigra
plays a major role in movement regulation
key reward system in the brain
sensory stimuli and movement
what is degeneration of nigrostriatal linked to
parkinsons disease
what and where is the mesolimbic system
ventral tegmental area
part of the limbic system( amygdala, nucleus accumbens)
reinforcement with reward or emotion
plays a key role in cognition
what is impairment in the mesolimbic system linked to
impairment in the mesolimbic dopaminergic system has been associated with non-motor symptoms, in particular mood disorders
what and where is the mesocortical system
ventral tegmental system
cognition, STM, planning and strategy , reward, learning, motivation
dopamine in this pathway helps modulate cognitive processes like attention and motivation
what is impairment in the mesocortical system linked to
addiction and mood disorders
can dopamine cross the blood brain barrier
no
how can we give patients more dopamine in the brain
gove patients dopamine precursor: L- Dopa- crosses BBB and synthesis dopamine
in addiction, what does increased usage lead to
ncreased usage leads to decreased sensitivity (e.g., damaged receptors) requiring larger doses for effects (or even to simply avoid withdrawal).
do serotonin synapses mostly produce IPSPS OR EPSPS
Most serotonergic synapses produce IPSPs. Most behavioural effects of serotonin are inhibitory.
2 selective serotonin re-uptake inhibitors (SSRIs)
Monoamine oxidase (This is an enzyme that binds to receptors on the post synaptic neuron to enhance the release of serotonin.)
and 5 H-T Transport
what does serotonin depletion cause and what can we take to cope
decreases sleep duration
injecting tryptophan (precursor to serotonin) can make you sleep
depletion related to depression
what is acetylcholine
A neurotransmitter that has been implicated namely in movement, arousal, attention, memory and motivation.
Thus, implicated in parasympathetic nervous system functioning.
what does tetrodotoxin block
locks acetylcholine receptors and acts as a sodium channel blocker (can’t fire an action potential!). Results in complete paralysis (including the diaphragm). Other toxins induce their effects via the degradation of acetylcholine when it is released in the synapse.
what is acetylcholine synthesised by
acetate and choline
can acetate bind directly to choline
Acetate cannot bind directly to choline and needs help from an enzyme and co- enzyme
what is acetylcholine broken down by
broken down by the enzyme acetylcholinesterase (AchE)
what are Cholinergic receptors
proteins on cell surfaces that respond to the neurotransmitter acetylcholine.
are cholinergic synapses IPSP OR EPSP
Cholinergic synapses are generally excitatory.
what are the 2 types of Cholinergic receptors
Nicotinic receptors (Ionotropic)
Muscarinic receptors (Metabotropic)
what are the bodies natural opioids
endorphins
what do neuropeptides consist of
2 or more amino acids
why are drugs like morphine and heroin so addictive
they act on the naturally occurring opioid synapses that are normally activated by the brains own endogenous opiates:
what is the most common neuropeptides
The most common neuropeptides are endogenous opiates (e.g. endorphins
what happens to receptors if a user does not take the drug they are addicted to
receptors crave the increased activation they were getting which is physically painful
where are large pain relieving receptors found in the body
There are a large pain relieving receptors in the gastrointestinal tract and taking exogenous ligands for our opioid receptors increases their population (just like smoking with nicotinic receptors) but also makes them super sensitive to these drugs rather than our own opioids
why is methadone helpful to drug users
Methadone seeks to attenuate this unpleasant side effect without the same additive effects.
what is the function of nitric oxide in neural activity
To augment blood flow to the neurons (increasing delivery neural fuel resources)
why are vasodilatory chemicals like nitric oxide released
are then released to widen arteries and facilitate an increase in blood flow to a specific area of the brain.
what is neuroplasticty
The capacity of the brain to adapt and modify neural connections in response to experience
what is hebbs rule
Hebbs rule
“Neurons that fire together, wire together”
what is neural plasticity.
Changes in the sensitivity of receptors
how can memories be recalled (neurons)
A network of neurons repeatedly activate together and so synaptic connections change.
This network could then be elicited (recalled) when triggered by the appropriate sensory neuron.
