Synaptic Transmission and Neurotransmitter Flashcards
Electrical synapses
two neurons are connected by a gap junction (connexion), which allows electrical current too flow directly from one cell to the other.
SNARE Protein
located in the synaptic vesicle (carries neurotransmitter) and the plasma membrane help dock the vesicles and zip together to force membrane fusion
Calcium binds to
synaptotagmin which triggers vesicle fusion and exocytosis of the neurotransmitter
Botulinum toxin prevents?
The release of neurotransmitters by cleaving the SNARE proteins at the presynaptic terminals and thus causes flaccid paralysis
Electrical synapse vs chemical synapse
Electrical: straight forward transducer of electricity. Cannot build highly compartmentalized system with just electrical. Fast transmission
Chemical: Neurons are electrically isolated. Chemicals are used to transmit signals. Can depolarize or hyperpolarize postsynaptic neuron. Can be fast or long lasting. Easier to build complex systems with.
Where are small molecule neurotransmitters made?
In the terminal
Where are peptides made?
In the cell body
Where can axon terminals synapse with other target neurons
Any part of the neuron; dendrites, cell bodies, and axons
Motor unit
One motor neuron and the muscle fiber it innervates
Small molecule neurotransmitter examples
ACh, ATP, GABA, Serotonin, Dopaminę, Norepinephrine, Epinephrine, Histamine
Gas examples of NT’s
Nitric oxide and carbon monoxide
NTs: Endocannabinoids (eCBs) ex. Anandamide and arachidonyl glycerol
eCBs go from the postsynaptic vesicle and connect to CB1 receptors on the presynaptic vesicle which go on to inhibit Ca2+ calcium channels which decreases neurotransmitter release from the presynaptic vesicle
Three types of NT receptors
1.) Ligand-gated ion channels (ionotropic receptors)
2.) G-protein-couple receptors (metabotropic receptors)
3.) Enzyme-linked receptors (tyrosine kinase receptors)
Ionotropic receptors are
ion channels
How does isoflurane work?
Agonist to bind to GABA receptors to open the channel. Works by increasing GABA mediated inhibitory tone in the CNS. It decreases the rate of GABA dissociation so it increases the duration of GABA activating the chloride channel which results in hyper polarization
Alcohol (ethanol) mimics what in the brain?
GABA; by binding to GABA receptors and inhibiting neuronal signaling
Ventral Tegmental Area
origin of dopaminergic cells bodies of the mesocorticolimbic dopamine system and other dopamine pathways; it is widely implicated in the drug and natural reward circuitry of the brain
Targets of G-proteins
Ion channels, enzymes, or gene transcription
Receptors ACh can work on
Ionotropic and metobotropic receptors
Termination of neurotransmitters
1.) Reuptake: NTs can be returned to axon terminals for reuse or transported into glial cells
2.) Breakdown: enzymes inactivate neurotransmitters
3.) Diffusion: Neurotransmitters can diffuse out of the synaptic cleft
Lidocaine
Voltage-gated Na+ channel blocker
Tetrodotoxin
Voltage-gated Na+ channel blocker
Botulinum toxin
Cleave SNARE proteins
Nerve gas binds to
binds to AChE and disable the AChE (acetylcholinesterase)
Curare binds to
nAChR (nicotinic acetylcholine receptors)
MDMA (ecstasy) binds to
Dopamine and 5-HT transporter
Cocaine binds to
Dopamine transporter
SSRIs binds to
5-HT transport
Lidocaine mechanism of action
inhibits influx of Na+ ions through ION-SELECTIVE sodium channels in nerve membrane leading to AP blockage
Tetrodotoxin mechanism
Inhibits voltage-gated sodium channels inhibiting depolarization in nerve and muscle cells
Nerve gas mechanism of action
Binds to and disables acetylcholinesterase which increases ACh levels triggering long-lasting muscle contraction
Curare mechanism of action
Binds to nicotinic acetylcholine receptor and causes muscle weakness and death because it can paralyze the diaphragm. Death arrows from South and Central America
MDMA (Ecstasy) mechanism of action
Increases the activity of dopamine, norepinephrine, and serotonin (5-HT) and it blocks the re-uptake of them
Cocaine mechanism of action
Binds to dopamine transporters and blocks the DA uptake, increasing DA levels in the synaptic cleft
SSRI mechanism of action
Bind to 5-HT transporter in the presynaptic terminal and increases the serotonin levels in the synaptic cleft
