Exam 2: Neurochemistry

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Myelin
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Schwann Cell & oligodendrocyte
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Direct Ionotropic
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Faster because when the EPSP-Na in IPSP-K or Cl out
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Excitatory
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Acetylcholine, glutamate, aspartate (make EPSPs)
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Inhibitory
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GABA, glycine (make IPSPs)
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Modulatory
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Dopamine, norepinephrine, epinephrine, serotonin (depends, could be either EPSP or IPSP)
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Acetylcholine
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The most widespread neurotransmitter in the nervous system Synthesized from dietary choline & acetyl (coenzymeA from Krebs cycle) *Decreased = muscle weakness & Alzheimer’s* Motor neurons: spinal nerves & cranial nerves
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Myasthenia gravis
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Autoimmune disorder Antibodies block acetylcholine receptor Muscle weakness
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AChR blockers
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Cause paralysis Some are irreversible
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Glutamate (& aspartate)
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Most common neurotransmitter in the brain Increased release induces epilepsy Causes EPSP (graded potential, Na comes in)
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ALS: Amyotrophic Lateral Sclerosis
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Lou Gehrig’s disease The brain is smart and active, the body cannot move Too much glutamate causes motor neurons to die
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GABA (& glycine)
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Made from glutamate Decreases action potential firing probability Used for sedation, anesthesia, anti-anxiety (valium, xanax) Barbiturates: drugs of abuse, cause sedation (nembutal, seconal) Alcohol INITIALLY decreases anxiety by increasing GABA inhibition-then the brain overcompensates and increases glutamate production (4-6 hours)
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Glycine
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Strychnine (rat poison) -Blocks glycine receptors, inducing seizures -Seizures caused by 1. Too much glutamate/aspartate 2. Not enough GABA/glycine
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Catecholamines
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Tyronsine->LDOPA->dopamine->norepinephrine->epinephrine
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Dopamine
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Substantia nigra is main source of dopamine Parkinson’s disease=death of brainstem substantia nigra neurons (shaking, not enough dopamine) Schizophrenia=increased dopamine
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Norepinephrine/Noradrenaline
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Locus Coeruleus is main source of norepinephrine Decreased NE=depression Increased NE=mania e.g., Bipolar disorder
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Epinephrine/Adrenaline
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Role of epinephrine in CNS not well characterized
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Serotonin (5-HT)
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Brainstem raphe nuclei are main source of serotonin Increased 5-HT=pain inhibition, start sleep (tryptophan: turkey) Decrease 5-HT=depression
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Peptide Neurotransmitters
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Substance P-conveys pain from the periphery (its a protein)
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Endorphins
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Endogenous opiods
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Endocannabinoids
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Mimic THC (marijuana) Play an important role in regulating feeding

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