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29 Cards in this Set
- Front
- Back
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Ligands
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Molecules that binds to receptors exactly and active or block them
-Endogenous Ligand: (neurotransmitter) binds a receptor & activates opening of a channel -Exogenous: (a drug) binds & may activate the receptor; an agonist -Other ligands: May bind and block but do not activate it; antagonists |
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Postsynaptic Receptors
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Determine the action of the transmitter
Ex: ACh can be excitatory, and open channels for NA+ & K+ Or can be inhibitory, and open channels for Cl- |
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Curare and Bungarotoxin
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Antagonists that:
Fit on receptors and BLOCK ACh or Cholinergic receptors |
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Nicotine
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can mimic ACh and act like a transmitter
Agonist of the receptor |
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Degradation
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Rapid breakdown and inactivation of transmitter by an enzyme
-Acetylcholinesterase(AChE) breaks down ACh and recycles it |
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Reuptake
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Transmitter is cleared from synapse by being absored back into the presynaptic axon terminal
-Transporters are special proteins that bring the transmitter back inside |
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Endogenous
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(internal substance) Chemical neurotransmitter released by the presynaptic neuron
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Exogenous
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(external substance) -from external sources
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Sequence of Synaptic Transmission
(7 steps) |
1. Action potential arrives at presynaptic axon terminal
2. Voltage-gated calcium channels in the terminal membrane open & Ca2+ ions enter. 3. Calcium cause synaptic vessels(filled w/a nuerotrans.) to fuse with presynaptic membrane; releasing the nuerotrans. into the synaptic cleft. 4. Transmitters bind to the post-synaptic receptor molecules; causing the opening of ion channels & leading to an EPSP or IPSP. 5. EPSP or IPSP spread toward post-synaptic axon hillock. 6. Synaptic transmission is rapidly stopped 7. Transmitter may activate pre-synaptic receptors, decreasing transmitter release. |
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Agonistic
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Activates receptor
1.increases synthesis of NT molecules 2.increases NT by destroying degrading enzymes 3.increase release of NT from terminal buttons 4.drug binds to autoreceptors & blocks the inhibitory effect 5.Drug binds to postsynaptic receptors and activates(increases) the effect 6.Block deactivation of NT (ex cocaine & methamphetamine |
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Antagonistic
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Disallows receptor to open
1.Block synthesis of NT 2.cause NT to leak out from vesicles, which then can be destroyed by an enzyme 3.Block release of NT 4.Activate autoreceptors and inhibit release of NT 5.Acts as a receptor blocker (PCP) |
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Ionotropic Receptor
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-Are fast. They quickly change shape and open or close an ion channel when the transmitter molecule binds
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Metatropic Receptor
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-Are slow. When activated they alter chemical reaction in the cell, -Uses second messengers to open an ion channel (indirectly lets in ions)
-Cause lasting change in a cell. (can change gene expression) |
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Exocytosis
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A cellular process that results in the release of a substance outside of the cell
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Criteria for a neurotransmitter:
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1.able to be synthesized in the presynaptic neuron & stored in axon terminal
2.is released when the action potential reaches the terminals 3.is recognized by post-synaptic membrane receptors 4.causes changes in the post-synaptic membrane 5.If it's release is blocked it can not affect the post-synaptic membrane |
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Types of neurotransmitters:
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-Amine Neurotransmitters
-Amino Acid Neurotransmitters -Peptide Neurotransmitters -Gas Neurotransmitters |
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Amine Neurotransmitters
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acetylcholine,
norepinephrine, epinephrine(adrenaline), dopamine, melatonin, serotonin (important for aspects of behavior: mood, anxiety, sleep) |
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Amino Acid Neurotransmitters
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GABA, glutamate, glycine, histamine
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Peptide Neurotransmitters
(Neuropeptides) |
oxytocin, vasopressin
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Gas Neurotransmitters
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Nitric acid, carbon monoxide
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Alzheimers Disease
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Loss of Acetylcholine (ACh) neurons or cholinergic neurons
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Parkinsons Disease
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Loss of dopamine neurons
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Acetylcholine (ACh)
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a neurotransmitter that is produced and released by neurons
-first transmitter to be discovered by Otto Loewi -plays major role in fore brain transmission -Role in learning and memory (cerebral cortex, amygdala, hippocampus) -Cholinergic neurons carry ACh* (located in basal forebrain) |
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Dopamine
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-important in behavior
-Mesostriatal pathway: motor control & originates in substantia nigra (mid brain) -PARKINSONS DISEASE -Mesolimbrocortical pathway: learning shaped by positive reinforcement & originates in ventral tegmental area(VTA) [reward, feelings of pleasure, addictive behaviors] -SCHIZOPHRENIA |
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Serotonin (5-HT)
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Main role: Behavior: mood, vision, sexual behavior, anxiety, sleep, etc.
Ex: Prozac causes serotonin to accumulate and can relieve depression and anxiety Serotonergic Neurons: found along the midline of midbrain and brainstem, and in the raphe nuclei |
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Norepinephrine (NE, or noradrenaline)
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Important for the control in behaviors that range from alertness to mood to sexual behavior.
Located in two regions: -The locus coeruleus("blue spot") and The lateral tegmental area. |
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Amino Acid transmitters:
Glycine, Glutamate, GABA |
Glutamate: Excitatory. interacts with several receptors such as NMDA (which plays major role in memory)
GABA: Inhibitory: -GABA(A): Ionotropic inhibitory effects by allowing Cl- to flow into the cell -Benzodiazepines: reduce anxiety, ex: Valium and Ativan |
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Peptides:
Opioid peptides |
mimic opioid drugs such as morphine and reduce pain perception
found in gut peptide hormones: oxytocin and vasopressin |
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Gas neurotransmitters:
How does it differ from other neurotransmitters? |
1. Is produced outside of axon terminals (mainly in dendrites) and defuses as soon as its produced
2. No receptors involved: it defuses into target cell and activates second messengers 3. Can function as a retrograde transmitter |
