Neurochemistry (2) Flashcards
who discovered neurotransmitters and how
loewi
he used frogs and stimulated the vagus nerve in one frog to produce ACh and then took the ACh and put it on the heart of another frog. the chemical made the heart change speeds
what is a type 1 synapse and what function are they associated with
asymmetrical; EPSP
what is a type 2 synapse and what function are they associated with
symmetrical; IPSP
where are neurotransmitters produced
amino acids/amines are produced in the presynaptic terminal
peptides are produced in the soma and transported down the axons
what are the steps leading to neurotransmitter release from pre synaptic terminals
action potential is reached and Ca2+ channels open, Ca2+ released the vesicles, the vesicles dock to the presynaptic membrane, the pre synaptic membrane opens (exocytosis) and the neurotransmitter is released into the synapse
what are two ways that neurotransmitters are deactivated when they are released in the synapse
reuptake and degradation
what determines the effects of a specific neurotransmitter
the receptors that the neurotransmitters bind to
what are the different subtypes of neurotransmitter receptors
ionotropic: transmitter-gated ion channels
metabotropic: g-protein coupled receptor
what are the four major types of NT receptors
ionotropic, metabotropic, enzyme-linked, intracellular
what is the general protein structure of ionotropic receptors
5 protein subunits where each subunit contains 4 alpha helicies
what is the general protein structure of metabotropic receptors
single polypeptide with 7 membrane spanning regions
what are the different kinds of receptors based on location
heteroreceptors: respond to NT different than the ones contained in its synaptic vesicles
autoreceptors: respond to NT released from its own synaptic vesicles
what are the 7 criteria for determining if a substance is a neurotransmitter
- found in pre synaptic terminal
- has enzymes for synthesis
- released from presynaptic terminal
- action on a postsynaptic neuron
- has postsynaptic receptors
- undergoes deactivation
- has predictable effects
what is the synthetic/metabolic pathway for GABA
glutamine –> (glutaminase) –> glutamate –> (glutamic acid decarboxylase) –> GABA
what is synthetic/metabolic pathway for the catecholamine neurotransmitters
phenylalanine (phenylalanine hydroxylase) tyrosine (tyrosine hydroxylase) dopa (aromatic l-amino acid decarboxylase) dopamine (dopamine beta hydroxylase) norepinephrine (phenylethtanolamine-N-methyltransferase) epinephrine
what are retrograde messengers
synthesized in post synaptic elements and flows post to pre
which neurotransmitters are retrograde messengers
endocannabinoids and soluble gases
what is dale’s principle
a neuron releases the same neurotransmitter at all its synapses
what are the three main components of a signaling system
molecular signal, receptor molecule, target effector/response molecule
what are the main effector cascades
g-proteins, second messengers, nuclear messengers
how do g-proteins activation regulate second messengers
number of things available (ex. ATP that is in cell to use)
what is the function of activated beta/gamma subunits
remain on membrane
which g-protein subunit is mainly responsible for the production of cyclic nucleotide second-messengers
alpha subunit
alpha stimulatory will increase production
alpha inhibitory will decrease production of cyclic AMP
can also interact with adenyl cyclase in the membrane to produce cAMP from ATP
what are the targets of second messengers
protein kinases (adding phosphate groups) through phosphorylation can effect gene expression
