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56 Cards in this Set
- Front
- Back
ependymal cells
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line cavities of the brain and spinal cord
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catecholamine neurotransmitters and what are they derived from
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dopamine, norepi, and epi; derived from L-tyrosine
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what is serotonin synthesized from
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tryptophan
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what is acetylcholine derived from
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choline, supplied from diet or synthesized and stored as part of phosphatidylcholine
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what are glutamate and GABA derived from
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alpha-ketoglutarate in the TCA cycle
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what is glycine derived from
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serine in brain
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ischemia causes what in brain
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increased calcium, swelling, glutamate excitotoxicity, and NO generation
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disorder of peroxisomal fxn
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Refsum disease=interference in very long chain fatty acid oxidation and alpha-oxidation
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lysosomal disease
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mucopolysaccharidoses-inability to degrade complex lipids and glycolipids
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astrocyte fxns
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phagocytizing debris left behind by cells, providing lactate (from glucose metabolism) as carbon source for neurons, and controlling brain extracellular ionic environment (regulate ECF)
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glucose transport in brain
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GLUT-1 transporter across endothelial membranes and GLUT-3 on neurons
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at what level do ppl begin feeling hypoglycemic symptoms
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~60 mg/dL
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what other monocarboxylic acids are transported into the brain
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L-lactate, acetate, pyruvate, and ketone bodies (acetoacetate and B-hydroxybutyrate)
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treatment of ppl with GLUT1 deficiency syndrome
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high fat, low car diet to force ketone body formation
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what causes mental retardation (at least in part) in PKU and maple syrup urine diseaes
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high levels of either phenylalanine or branch-chained aas; results in competative inhibition of other large, neutral aas
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what are the large, neutral aas (LNAAs)
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phenylalanine, leucine, tyrosine, isoleucine, valine, tryptophan, methionine, and histidine
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how does insulin, transferrin, and ILGF cross blood-brain barrier
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receptor-mediated transcytosis
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major small N-containing molecule neurotransmitters
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glutamate, GABA, glycine, acetylcholine, dopamine, norepi, serotonin, and histamine (also aspartate, epi, and NO)
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neuropeptides
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endorphins, GH, TSH
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reserpine
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blocks catecholamine uptake into vesicles
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where does tyrosine come from
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diet of synthesized in liver from phenylalanine
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first and rate limiting steps of catecholamine synthesis from tyrosine
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hydroxylation of tyrosine ring by tyrosine hydroxylase
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where is the enzyme required to form norpei from dopamine located
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within storage vesicles
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epinephrine synthesis required adequate B12 and folate due to
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use of SAM
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what transports catecholamines into vesicles
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protein VMAT2 (vesicle monoamine transporter 2); driven by H+ gradient across membrane
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MAO-A
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preferentially deaminates norepi and serotonin
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MOA-B
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wide spectrum of phenylethylamines
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indicator of dopamine degradation
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cerebrospinal homovanillylmandelic acid (HVA); decreased in Parkinson's
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tyramine
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degradation product of tyrosine that can cause headaches, palpitations, nausea, and vomiting, and elevated BP in large quantities; mimics norepi; inactivated by MAO-A
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phenoxybenzamine
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a1 and a2 adrenergic receptor antagonist
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what foods contain tyramine
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cheese, wine; processed over long periods
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histaminergic neurons are found
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in tuberomammilary nucleus of posterior basal hypothalamus; project to nearly all areas of CNS
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histamine is derived from
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histidine in single enzymatic step
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histamine effects in allergic response
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vasodilation and increase permeability of blood vessel walls
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histamine in brain
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excitatory neurotransmitter; hence antihistamines have SE of drowsiness
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formation of SAM via recycling of homocysteine requires
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tetrahydrofolate and vit B12
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Tiagabine
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inhibits reuptake of GABA from the synapse; treat epilepsy and other convulsant disorders
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synthesis of glutamate in neurons
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generally synthesized de novo tather than taken up from blood; TCA cycle derived from a-ketoglutarate
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GABA synthesis
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decarboxylation of glutamate in single step
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GABA shunt
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uptake of GABA in glial cells which convert to glutamine and then transport to neurons which convert back to glutamate
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aspartate synthesis
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excitatory; TCA cycle from oxaloacetate via transamination; can't pass through blood-brain barrier
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glycine synthesis
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major inhibitory of spinal cord; de novo within nerve terminal from serine; requires folic acid
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NO is synthesized from
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arginine via NO synthase
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what does NO activate in target cells
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soluble guanylate cyclase increasing cGMP
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cGMP in smooth muscle
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activates one or more protein kinases causing relaxation and dilation
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possible retrograde messengers in CNS
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NO, arachidonic acid, CO
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symptoms of hypoglycemia from 45 to 36 mg/dL are mostly due to
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decrease neurotransmitter synthesis
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hypoglycemia below 1 mM (18 mg/dL)
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high energy P levels depleted, EEG become isoelectric, and neuronal cell death ensues
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what brain areas are particularly sensitive to hypoglycemia
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hippocampal and cortical structures
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glutamate excitotoxicity in hypoglycemia
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failure of energy-dependent reuptake pumps-leads to prolonged opening of receptor ion channel and influx of lethal amounts of Ca2+
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effect of oxaloacetate use to make glutamate
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must be replaced in order for oxidation of acetyl CoA to continue-2 pathways
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what esential fatty acids enter the brain
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linoleic and linolenic acid; all others synthesized
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oligodendrocyte myelin synthesis per day
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4 times its own weight
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Two proteins in CNS that constitute 60-80% of total
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proteolipid protein (PLP) and myelin basic proteins (MBPs)
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PLP
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hydrophobic and forms large aggregates in aqueous soln and relatively resistant to proteolysis; highly conserved; promote formation and stabilization of multilayered myelin structure
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MBPs
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extracted from membrane and soluble in aqueous soln; located on cytoplasmic face of myelin membranes
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