Neurotransmision s and r Flashcards
Describe the information flow in neurons:
Information is received form the dendrites; Processed (summed) at the axon hillock; if triggered the action potential travels down to axon; to the synaptic cleft
Transmitters released from the nerve terminal activates what? This causes what?
Transmitters released from the nerve terminal activates post-synaptic receptors and causes an influx of ions or activation of second messengers
in the cycle of transmission of a neurotransmitter describe the step from synthesis to just before release
Synthesis in cell body; anterograde transportation to nerve ending; uptake into synaptic vesicles; storage in synaptic vesicles; release to synaptic cleft;
in the cycle of transmission of a neurotransmitter describe the step from release to degradation
Released to synaptic cleft; binding to and activation of post-synaptic receptors; the neurotransmitter can then be processed in one of three ways Extracellular enzyme destruction; reuptake direct into the terminal OR Reuptake into the cellular compartment then converted to an inactive metabolite and reused as needed;
what is the extremely simplified cycle of neurotransmission?
Release-> Action (receptor binding) -> disposal (re-uptake)
What are the three main types of neurotransmitters?
Excitatory (+ firing likelihood); inhibitory (- firing likelihood); neuromodulators
the likelihood of action potential is determined by? Where is this determination made?
Likelihood of action potential is determined by the summation of all inputs At the Axon hillock
What are the two most widely used amino acid transmitters in the CNS? Generally what is there function?
Glutamate (excitatory); GABA (inhibitory)
GABA and Glutamate can be what?
Interconverted by a single enzymic step
Both GABA and Glutamate are derived from what cycle? What molecule can they be converted from?
The TCA cycle; Alpha-Ketoglutarate -> Glutamate -> GABA -> Succinate
Glutamate is involved in what?
Learning and memory; many neuro-psychiatric diseases
GABA-alpha receptor is the stir of action of what kind of drugs? Give some examples
GABA-alpha receptor is the site of action of many psychoactive drugs including; alcohol; barbiturates; tranquilizers
in excitotoxicity there is an imbalance between?
There is an imbalance between excitatory and inhibitory signals;
What is the most common Neurotransmitter in the peripheral nerves?
Acetylcholine (Ach)
Acetylcholine is synthesised from what? This process requires what and utilises what enzyme?
Choline; The process requires ATP and the enzyme that is used is choline acetyltransferase
what are the two main Catecholamine neurotransmitters?
Dopamine; noradrenaline
Catecholamine’s are derivatives of what neurotransmitter?
Tyrosine
Dopamine receptors can do what to cAMP? What are the receptor types for each?
both increase or decrease cAMP; D1 like receptors (D1 and D5) increase while D2 like (D2; D3 and D4) decrease
antipsychotics are D2 what? Antiparkinsonian are D2 what
antipsychotics are D2 antagonists; Antiparkinsonian drugs are D2 agonists;
cocaine and amphetamines block what?
Dopamine transporter
Peptide transmitters precursors are synthesised in the what? What happens to them post releases?
Peptide transmitter are synthesised in the Golgi apparatus; post realise they are degraded in the synaptic cleft they are not reused
Fast Release transmitters are storied where? What are their actions post depolarisations?
Attached to an asctin web in the terminal; when an action potential arrives at the terminal it causes an influx of Ca+2; docked vesicles then fuse with the membrane releasing there neurotransmitters into the cleft; empty vesicles are then recycled and refiled; the actin web breaks down and new vesicles move to dock
Slow release neurotransmitters are located where? What are their actions post depolarisations?
Slow release transmitters are not located on the cell membrane; Trains of action potentials are required o mover them to the membrane before contents can be released
Describe kiss and run; what transmitters utilise this system?
Synaptic vesicles merge with the cell membrane but do not fully discharge their contents into the cleft; the vesicle then is re-filled with the neurotransmitters that where lost; slow release
what are the two common receptor actions?
Ion fluxes; second-messenger cascades
contrast hormone receptors and neurotransmitter receptors
Hormones are slow release they affect receptors at long range and they have very high affinity for the hormone; Neurotransmitters are fast released they affect receptors at a very short range and they have lower affinity for the neurotransmitter
most G-coupled receptors are composed of how may proteins; how many transmembrane domains?
single proteins with 7 transmembrane domains; multi-protein complexes each subunit has 4 transmembrane domains
most ion gated channel receptors are composed of how may proteins; how many transmembrane domains?
multi-protein complexes in which each subunit has 4 transmembrane domains
in the resting state an ion channel is what?
Closed
When activated the ion channel receptor undergoes what? This allows?
A conformation change; allows ions to flow into the cell
what do cations and anions do to the cell? Give example of both
Cations (K / Na/ Ca) depolarize the cell; Anions (Cl) hyperpolarize
at the Neuromuscular junction what receptor is activated?
Nicotinic acetylcholine receptor
at the Neuromuscular junction What neurotransmitter is used? what degrades this neurotransmitter?
Acetylcholine; acetylcholinesterase;
On a Ligand-Gated Ion Channel there are how many binding sites? These can bind?
multiple binding sites; can bind agonists or modulators
describe the mechanism of activating a g-protein linked receptor
agonis activation -> conformation change -> alter second-messenger -> turn over in the cell
there are _______ receptors for each neurotransmitter?
Multiple
neurotransmitter transporters are all Coupled with? Glutamate’s transporter is also coupled with?
GABA glycine dopamine noradrenaline and serotonin transports are also coupled with?
Neurotransmitter transporters are driven by?
ionic gradients
