NEUROTRANSMITTERS AND BRAIN PATHWAY Flashcards
What are neurotoxins?
toxins that are destructive to nerve tissue
what are the 2 types of neurotransmitters?
small molecule neurotransmitters
(amino acids/monoamines/gases) and neuropeptides
describe the process of synthesising small molecule neurotransmitters
enzymes are synthesised in the cell body and are transported slowly down the axon. neurotransmitters are synthesised and packaged at the presynaptic terminal.
describe the process of synthesising peptide transmitters?
neurotransmitters precursors and enzymes are synthesised in the nucleus in the cell body and ae transported down microtubule tracts to the axon terminal where enzymes modify pre-peptides to produce peptide neurotransmitters,
what is co-transmission?
when a neuron releases more than one neurotransmitter
what neurotransmitters are released in low frequency stimulation?
release of small neurotransmitters
what neurotransmitters are released in high frequency stimulation?
releases neuropeptides and small neurotransmitters
what is the criteria that makes a chemical messenger a neurotransmitter?
- chemical must be synthesised and present in a neurone
- when released the chemical must produce a response in a target cell
- there must be a mechanism for removal after the chemicals work is done
- specific receptors for the chemical must be present on the postsynaptic cell
what do cholinergic neurones contain?
acetylcholine
what do catecholaminergic neurones contain?
noradrenaline/adrenaline/dopamine
what is an inotropic receptor?
5 subunits which form an ion channel. the gating is regulated by an agonist binding allosterically to the receptor.
what is a metabotropic receptor?
a receptor that uses signal transduction mechanisms e.g. G-protein coupled receptor
what are the receptors for ACh?
nicotinic (sympathetic)
muscarinic (parasympathetic)
what is ACh needed for?
learning, memory, sleep, arousal, aggression. biorhythms, thermoregulation, sexual behaviour
how can ACh be broken down?
by acetylcholinesterase into acetic acid and choline
what are the 3 amino acid neurotransmitters?
glutamate
GABA
glycine
what is glutamate important for?q
normal brain function. they are excitatory
where does glutamate come from?
glutamine using glutaminase.
where is released glutamate uptaken?
presynaptic terminal and glial cells using glutamate transporters
what are the types of glutamate receptors?
AMPA, NMDA and kainite. there are also some metabotropic receptors
how is GABA formed?
from glutamate via glutamic acid decarboxylase
what are GABAergic neurones for?
they’re the main source of inhibition
when GABA is released, how is it uptown again?
transporters on the presynaptic terminal and glial cells uptake it.
describe valium’s/diazepam’s mechanism of action?
interacts with the GABA receptor to increase the influx of Cl- ions into the neuron to hyperpolarise it and inhibit any action potentials. This is great at calming you down and is used for anxiety.
