Term
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Definition
| inadequate intake of both protein and energy. It is characterized by severe tissue wasting. |
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Term
| Kwasiorkor? Also, what mechanisms contribute to the swollen belly? |
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Definition
inadequate intake of protein with adequate energy intake, often precipitated by infection leading to a catabolic state. Swollen belly due to edema is common.
Mechanisms: First, the appearance of ascites due to increased capillary permeability from the increased production of cysteinyl leukotrienes (LTC4 and LTE4) as a result of generalized intracellular deficiency of glutathione. Tolga is thought to be attributed to the effect of malnutrition on reducing plasma proteins (discussed below), resulting in a reduced oncotic pressure and therefore increased osmotic flux through the capillary wall. A second cause may be due to a grossly enlarged liver due to fatty liver. This fatty change occurs because of the lack of apolipoproteins which transport lipids(cholesterol) from the liver to tissues throughout the body. |
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Term
| What factors increase protein synthesis from amino acids in muscle |
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Definition
| Activity, Insulin, IGFs, Norepinephrine, testosterone |
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Term
| What factors increase amino acid synthesis from protein breakdown in muscle |
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Definition
| decrease in insulin, cortisol and thyroid hormone (T3) |
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Term
| During fasting what factors lead to a net proteolysis |
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Definition
| Decreased insulin, increased cortisol |
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Term
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Definition
| These amino acids (valine, leucine and isoleucine) are an important fuel source for skeletal muscle. Unlike most amino acids, the liver absorbs little of these amino acids after a meal. These three amino acids constitute ~20% of dietary protein but constitute ~70% of the amino acids leaving the liver following a meal. The branch-chain amino acids are preferentially removed from the blood by muscle where they are both used for protein synthesis and oxidized as a fuel source. |
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Term
| Where are essential amino acids stored |
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Definition
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Term
| What Cofactor do transaminases use |
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Definition
| pyridoxal phosphate (PLP, vitamin B6 derivative) |
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Term
| Elevated plasma levels of what can indicate heart or liver damage? |
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Definition
| alanine transaminase (ALT) and aspartate transaminase (AST) in plasma indicates damage to tissues rich in these enzymes |
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Term
| What enzyme incorperates NH4+ into Alpha ketogluterate producing glutamate or vica versa. What are positive allosteric effectors for formattion of glutamate |
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Definition
glutamate dehydrogenase
ATP and GTP are positive
allosteric effectors of the formation of glutamate |
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Term
| what is the major amino acid found in the circulatory system |
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Definition
| glutamine, followed by alanine as the second most concentrated plasma amino acid |
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Term
| What reaction does glutamine sythase catalyze? Where is this enzyme found? |
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Definition
Glutamate + ATP + NH3 → Glutamine + ADP + phosphate
found in perivenous hepatocytes |
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Term
What reaction does glutaminase catalyze?
Where is this enzyme found? |
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Definition
Glutamine + H2O → Glutamate + NH3
Glutaminase is expressed in periportal hepatocytes, where it generates NH3 (ammonia) for urea synthesis, as does glutamate dehydrogenase.
Glutaminase is also expressed in the epithelial cells of the renal tubules, where the produced ammonia is excreted as ammonium ions. This excretion of ammonium ions is an important mechanism of renal acid-base regulation. During an acidosis, glutaminase is induced in the kidney, which leads to an increase in the amount of ammonium ions excreted |
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Term
| Where does the amino group from catabolism of branched chain amino acides end up. |
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Definition
| on pyruvate resulting in alanine or on alpha-ketoglutarate resulting in glutamate and then glutamine. Therefore, the catabolism of branch-chain amino acids by skeletal muscle results in a release of glutamine and alanine into the blood. |
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Term
| Where do the nitrogens on urea come from |
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Definition
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Term
| What does carbamoyl phosphate synthetase I do? Where does this take place? What is the regulator of this enzyme? |
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Definition
makes carbamoyl phosphate from NH4
+ and CO2 and 2 ATPs. The CO2 (as HCO3
-) comes from mitochondrial respiration. Takes place in liver mitochondria. N-acetylglutamate positively regulates CPSI. |
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Term
| what does ornithine transcarbamoylase do? |
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Definition
| adds the carbamoyl group to ornithine to make citrulline. Ornithine plays a role analogous to oxaloacetate in the TCA cycle, accepting material at each turn of the cycle |
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Term
| What does argininosuccinate synthetase do? Where does this take place? |
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Definition
| Citrulline passes into the cytosol and is combined with aspartate by argininosuccinate synthetase to make argininosuccinate |
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Term
| What is the rate-limiting step of the urea cylce? What enzyme catalyzes this step? |
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Definition
| The first step catalyzed by CPSI (carbamoyl phosphate synthetase I) |
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Term
| What does argininosuccinate lyase do? |
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Definition
| cleaves argininosuccinate into fumarate and arginine |
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Term
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Definition
| cleaves arginine to yield urea and ornithine. |
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Term
| Where do the urea cycle steps occur? Specifically and generally |
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Definition
| Steps 1 and 2 occur in the mitochondria; steps 3,4, and 5 occur in the cytosol. The pathway only occurs in the liver |
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Term
| What is used to treat CPSD, OTCD and ASD(Arginosuccinate synthetase) patients |
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Definition
| The aromatic acids benzoate and phenylacetate are used to treat CPSD, OTCD and ASD patients because they combine with glycine and glutamine, respectively, and are excreted |
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Term
| What is used to treat ALD(Arginosuccinate lyase) patients |
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Definition
ALD is treated with arginine
supplements. This promotes synthesis of argininosuccinate, which can be excreted into urine |
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