Neurotransmitters Flashcards
what causes the release of NT into the synaptic cleft?
AP travels down the presynaptic terminal causing Ca2+ to flood down the concentration gradient causing the release
synthesising enzymes
presynaptic and glial cells reassemble NT to go again.
postsynaptic receptors
in the membrane, site of action, great heterogeneity.
presynpatic receptors
in the membrane, for reuptake (act as a brake).
degrading enzymes
released by the postsynaptic terminal, remove excess NT.
transporters
vacuum cleaners for extra NT in the synapse.
NT are either…
- Excitatory (increase the likelihood of an AP firing in postsynaptic neuron).
OR - Inhibitory (decrease the likelihood of an AP firing in postsynaptic neuron).
- Many NTs do both and it depends on the receptor(s).
types of NT receptors
ionotropic and metabotropic
ionotropic receptors
o Conduct ions (are ion channels)
o Faster
o Normally postsynaptic
o Directly affect membrane potential (as conduct ions)
metabotropic receptors
o Don’t conduct ions (they have no pores)
o Slower
o Normally presynaptic
o Modulatory (intracellular signalling which can modulate ionotropic receptors)
do NT contain both ionotropic and metabotropic receptors?
- Most NT have both ionotropic and metabotropic receptors
o >13 receptors for serotonin (most metabotropic)
how can NT be classified by their anatomical location?
general NT and restricted NT
general NT
o Glutamate (excitatory)
o GABA (inhibitory) (gamma-amino butyric acid)
o Glycine
o Acetylcholine (PNS)
o Noradrenaline (PNS)
restricted NT can…
(can act as neuromodulators – modulate NT or modulators)
restricted NT
o Serotonin (in raphe nuclei)
o Dopamine (in substantia nigra)
o Noradrenaline (CNS) (in locus coeruleus)
o Neuropeptides
o Acetylcholine (CNS) (in nucelus basalis of meyhert)
o Beta-endorphin
o Histamine
(Neuromodulators are normally more anatomically restricted)
