Neurotransmitters Flashcards
receptor (generator) potential vs. postsynaptic potential
-similarities
both are graded changes of membrane excitability that decay away from the site of stimulation
in each case, the membrane potential must be at some threshold level at the critical point on the axon (initial segment, axon hillock)i that contains the voltage-gated channels
if threshold depolarization is not achieved at this point, no AP is initiated
neurotransmitter mechanisms of influencing the postsynaptic cell
ionotropic
metabotropic
ionotropic neurotransmitters
- receptor location
- characteristics
- all _____ neurotransmitters are ionotropic
receptors are localized on actual ion channel
response is immediate
-channel opens then closes
all NM are ionotropic
metabotropic neurotransmitters
- receptor location
- to work, it requires what?
receptors are located at some point on the membrane but activate an ion channel some distance away via a second messenger system (g-protein-coupled receptors)
this requires some internal cellular mechanisms that may be long acting via changes in enzyme/protein expression
delayed response to open
classes of neurotransmitter-related compounds
fast neurotransmittters
neuropeptides
non-traditional neurotransmitters
fast neurotransmitters
- what type of neurotransmitter
- which one are typically excitatory; inhibitory
ionotropic excitatory -ACh -glutamate -epinephrine inhibitory -GABA -glycine each may also have a metabotropic receptor
neuropeptides
- what are they
- neurotransmitter type
- examples
more complex AA peptides from small to large all metabotropic examples -enkephalin -calcium binding protein -substance P
non-traditional neurotransmitters
- examples
- can affect…
nitric oxide
eiconasoids (prostaglandins, cannabinoids)
can affect adjacent cells
relationship between neurotransmitters and neuropeptides
neurotransmitters are co-localized with neuropeptides in axonal terminals
-i.e. GABA has been found with various classes of calcium binding proteins that are specific to different structures/regions of the brain
function of colocalization
exact function not clear
some indication is that the peptide acts as a neuromodulator by modifying the activity of the cell during neurotransmission, as well as prolonging membrane activity
what determines the action of a neurotransmitter (excitatory vs inhibitory)
post-synaptic receptor
which class of fast neurotransmitters only act through metabotropic receptors
catecholamines
specific neurotransmitters that you should know
acetylcholine
gamma-aminobutyric acid (GABA)
catecolamines (norepinephrine, epinephrine, dopamine)
glutamate
