Flashcards in lipoprotein stuff Deck (12):
describe lipoprotein uptake from the diet
cholesterol and triglycerides are eaten, then abosrbed by the intestinal cells. the intestinal cells put them directly into the systemic circulation via chylomicrons. lipoprotein lipase converts chylomicrons to free fatty acids, glycerol, and chylomicron remnants.
free fatty acids: either stored in adipose tissue or used by muscle and other peripheral tissues for food.
glycerol: taken up by liver and used for glucose synthesis.
remnants: taken up by liver via endocytosis or via HDL uptake.
endogenous lipid transport
liver secretes VLDL. VLDL is made into FFAs and LDL via lipoprotein lipase. FFAs go to adipose tissue or to peripheral tissues like muscle. LDL is taken up by LDL receptors in liver or in periphery. if in periphery, LDL is broken into cholesterol and cholesterol esters and released to the blood. HDL picks up cholesterol esters and returns them to the liver.
in the liver, LDL inhibits cholesterol synthesis but also inhibits LDL receptors. net effect of increasing LDL levels
A1- activates LCAT, whic acts to trap cholesterol esters within HDL. deficits in A1 lead to HDL deficiencies.
B48 and B100.
B48: involved in synthesiss and secretion of chylomicrons from the small intestine.
B100: binds LDL receptor to facilitate LDL binding. also found in VLDL.
apolipoprotein B48 deficiency
abetalipoproteinemia. patients can't absorb dietary fats. they have fat soluble vitamin deficiencies, failure to thrive fatty stinky stools, intellectual disability, balance and coordination problems, ACANTHOSIS, RETINOSIS PIGMENTOSA
apoprotein B100 defeciency
defective B100 causes increased LDL levels because of poor LDL/LDLR binding.
many types. basically, FA says to know that CII activates lipoprotein lipase. deficiencies lead to hyperlipoproteinemia with lots of chylomicrons and HDL.
act to transport TGs and cholesterol to the liver and helps with remnant uptake. found everywhere but LDL.
E4 is associated with Alzheimer's disease
autosomal recessive disorder from homozygosity for E2, the binding defective form of apoE. defective apo E causes high levels of VLDL and IDL. chylomicron levels are found in plasma. patients have striae palmaris- deposits of cholesterol in the palmar creases.
treat: niacin and fibrates.
codominant disorder from mutations in the LDL receptor or an autosomal dominant disorder from defective apoprotein B100 (which facilitates binding).
increased LDL levels (low uptake, and the liver senses low levels and increases production).
patients have tendon xanthomas, severe atherosclerosis, tuberus xanthomas on the elbows and buttocks.
patients have elevated LDL lelvels.
treat with a statin and cholestyramine.
autosomal dominant disorder.
high triglycerides, probably related to overproduction of VLDL in the liver. high VLDL, total cholesterol, and TGs
often asymtomatic, but patients may have eruptive xanthomas and lipedemia retinalis, and pancreatitis. increased risk of vascular disease