Notes in L26 - Cholesterol Metabolism

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Published	11/02/2024	The conversion of HMG-CoA to mevalonate requires {{c1::2}} molecules of {{c1::NADPH}} as cofactors.
Published	11/02/2024	{{c1::SREBP-2}} is the transcription factor responsible for HMG CoA reductase expression. It is found in the {{c1::endoplasmic reticulum}} bound to {{…
Published	11/02/2024	Decreased DNA expression of HMG-CoA reductase is mediated by {{c1::high levels of cholesterol}}. {{c1::Cholesterol}} is capable of binding to {{c1::SR…
Published	11/02/2024	{{c1::SCAP}} is the key shuttle protein in the translocation of SREBP2 to the nucleus
Published	11/02/2024	What organelle is HMG CoA reductase associated with?{{c1::the smooth ER}}
Published	11/02/2024	{{c1::Cholesterol}}, {{c1::glucagon/epinephrine}}, and {{c1::AMPK}} inhibit HMG-CoA reductase, whereas {{c1::insulin}} activates it
Published	11/02/2024	Cholesterol synthesis is an energy-{{c1::dependent}} process. It requires both {{c1::NADPH}} and {{c1::ATP}}.
Published	11/02/2024	{{c1::Prenylation}} refers to the conjugation of cholesterol biosynthesis intermediates to membrane proteins in order to improve their hydrophobicity
Published	11/02/2024	{{c1::7-dehydrocholesterol}} is cholesterol synthesis intermediate precursor of vitamin D
Published	11/02/2024	By what two mechanisms do statins decrease total cholesterol?Primary mechanism: {{c1::reversible, competitive inhibition of HMG-CoA reductase}}Seconda…
Published	11/02/2024	Cholesterol is eliminated through the synthesis and excretion of {{c1::bile}}
Published	11/02/2024	Bile is composed primarily of {{c2::bile salts}}, {{c2::phospholipids}}, {{c1::cholesterol}}, and {{c1::bilirubin}}
Published	11/02/2024	What enzyme catalyzes the rate limiting step of bile acid synthesis?{{c1::cholesterol 7-α-hydroxylase}}
Published	11/02/2024	How is cholesterol 7-α-hydroxylase regulated?{{c1::DNA transcription is increased by cholesterol and decreased by bile}}
Published	11/02/2024	How is bile reabsorbed in enterohepatic circulation?
Published	11/02/2024	What causes the formation of cholelisthiases (gallstones)?{{c1::lack of sufficient bile salts in the bile}}
Published	11/02/2024	Gallstones can either be treated surgically through {{c1::cholecystectomy}} or non-surigically by {{c1::oral chenodeoxycholic acid bile salt}} supplem…
Published	11/02/2024	Vitamin D synthesis begins in the {{c1::liver}} with the production of {{c1::7-dehydrocholesterol}}. {{c1::7-dehydrocholesterol}} is then transported …
Published	11/02/2024	The {{c1::ileum}} is the site of bile salt reabsorption in the enterohepatic circulatory system.
Published	11/02/2024	cholesterol synthesis occurs in {{c1::all tissues}}, with the largest production taking place in the {{c1::liver}}
Published	11/02/2024	synthesis of cholesterol involves enzymes located in the {{c1::cytosol}}, {{c1::smooth ER}}, and {{c1::peroxisome}} and requires {{c1::ATP}} and {{c1:…
Published	11/02/2024	Increased DNA expression of HMG-CoA reductase is mediated by {{c1::low levels of cholesterol}}. {{c1::SCAP}} is released from {{c1…
Published	11/02/2024	when cholesterol levels are high, HMG CoA reductase protein is {{c1::ubiquinated}} and {{c1::broken down by the proteasome}}
Published	11/02/2024	when AMP levels rise, {{c1::AMPK}} is activated and {{c1::phosphorylates}} HMG CoA reductase, leading to {{c1::inactivation}}
Published	11/02/2024	{{c1::insulin}} favors the activation of phosphatases that lead to {{c1::dephosphorylation}} of HMG CoA reductase, thereby {{c1::activating}} choleste…
Published	11/02/2024	High intracellular concentrations of cholesterol {{c1::increase}} expression of {{c2::cholesterol 7-α-hydroxylase}} while bile acids {{c1::decrease}} …
Published	11/02/2024	The presence of the bile acids/salts are essential for keeping the non-esterified cholesterol and other components in bile {{c1::solubilized}}
Published	11/02/2024	gallstone formation is usually {{c1::asymptomatic}}, but significant accumulation can induce {{c1::inflammation}}
Published	11/02/2024	{{c1::oral chenodeoxycholic acid}} can supplement the body’s own production and can lead to dissolution of stones over the course of months to years.
Published	11/02/2024	what are the 3 locations that a gallstone may block?{{c1::cystic duct}} - {{c2::connects gallbladder to common bile duct}}{{c1::common bile duct}} - {…
Published	11/02/2024	blockage of the {{c1::ampulla of vater}} is serious and potentially-life threatening
Published	11/02/2024	a gallstone at the ampulla of Vater will block the {{c1::bile duct}} and the {{c1::flow of pancreatic secretions}}, ultimately leading to {{c2::pancre…
Published	11/02/2024	the 3 pharmacologic approaches to reduce cholesterol levels are?{{c1::bile acid sequestrants (Questran)ezetimibe (Zetia)statins}}
Published	11/02/2024	{{c2::Cholestyramine (Questran®)}} inhibits absorption of {{c1::bile salts}} in the small intestine, disrupting {{c1::enterohepatic}} circulation. Thi…
Published	11/02/2024	{{c1::ezetimibe (Zetia)}} inhibits NPC1L1-mediated uptake of {{c2::cholesterol}}. therefore, {{c2::less cholesterol is absorbed in the small intestine…
Published	11/02/2024	is there evidence that dietary cholesterol increases LDL cholesterol?{{c1::no}}
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