better Flashcards
4 neurotransmitter removal mechanisms
- Digestion by enzymes in the synaptic cleft
- Reuptake presynaptic neuron
- Uptake by surrounding glia
- Diffusion away from the synaptic cleft
acetylcholine receptor (nicotinic receptor) mechanism. what blocks acetylcholine receptor?
binds nicotine or acetylcholine. once neurotransmitter is bound, the channel opens allowing flow of Na and K. an EPSP is generated
using curare, a neurotoxin, the receptor can be blocked. you can use an acetylcholinesterase inhibitor to increase the efficacy of acetylcholine.
muscarinic acetylcholine receptor
monomeric g protein coupled receptor that can be inhibitory by activating K channels or excitatory by closing K channels.
glutamate
It is synthesized from glutamine by glutaminase, or from glucose. After binding to glu receptors, it is taken up by glial cells via EAAT which converts glu back to glutamine by glutamine synthase.
AMPA receptor
permeable to na and k, generates a fast excitatory postsynaptic potential
NMDA receptor
permeable to Na, K, and Ca. Mg blocks the receptor at resting membrane potential, depolarization relieves the block. Requires glycine and glutamate and depolarization to activate. Can sense when 2 things co-occur which mean its involved in learning and memory and excitotoxicity.
kainate receptor
permeable to Na and K. generates Excitatory postsynaptic currents that rise quickly and decay slowly.
excitatory postsynaptic receptors
Excitatory postsynaptic receptors (e.g., glutamate) allow for Na+ influx.
inhibitory postsynaptic receptors
Inhibitory postsynaptic receptors (e.g., GABA) allow for either Cl- influx or K+ efflux.
GABA A
inhibitory and has a hyperpolarizing response. uses a GABA/sodium symporter to actively reuptake GABA into presynaptic neurons and passively move sodium into the neuron.
ionotropic receptor
nt receptors have a diversity of subunits coming together to form them
metabotropic receptor
receptors are single proteins with many membrane spanning regions.
GABA receptor
target for CNS depressants like alcohol and ketamine. In the presence of GABA benzos increase frequency of openings, barbiturates increase the duration of openings. usually brings chloride into the cell through GABA gated ion channel that is permeable to Cl.
GABA in utero
exciting in utero because of the high intracellular chloride concentration before K/Cl cotransporters are expressed.
GABA B
inhibitory mediated by activation of K channels or blocking Ca channels.
glycine
synthesized from serine by serine enzyme. reuptake by glial cells or na/glycine cotransporter.
tyrosine
precursor for the catecholamines, dopamine, norepinephrine, and epinephrine.
dopamine
produced in the substantia nigra and ventral tegmental area (target for parkinson’s). Synthesized in synaptic terminal, loaded into vesicles by VMAT, action is terminated by glia or sodium mediated symporter (DAT) into presynaptic cell. Cocaine inhibits DAT. degraded by MAO in axon terminal
norepinephrine
Produced in the locus coeruleus from dopamine and regulates cardiovascular and respiratory blood vessels. can be excitatory or inhibitory depending on the receptor. NET clears it from the synaptic cleft. Loaded into vesicles by the same VMAT as dopamine.
epinephrine
produced from norepinephrine, uses VMAT and NET transporters, epinephrine neurons found in lateral tegmental system and medulla. Mediates sleep and appetite. Outside the CNS it acts as a hormone, adrenaline.
serotonin
Degraded by MAO in axon terminals like dopamine. Mostly metabotropic receptors, but some ionotropic receptors as well. Regulates mood and sleep and food, receptors or reuptake transporters are drug targets for antidepressants. Produced in raphe nuclei but effects are widespread.
histamine
Neurons found in hypothalamus, mediates arousal and attention. Synthesized from histidine and uses metabotropic receptors. Allergic reactions or tissue damage lead to histamine release from blood. We don’t know the transporter but we know MAO is used for degradation.
