What is the function of a chylomicron?
Delivers TG to peripheral tissues via LPL degradation of its TG
What is the function of VLDL?
Delivers TG to periphery; secreted by liver
Function of ApoC-II
Cofactor for LPL (which degrades TG in chlyomicrons and VLDL)
Alcohol increases synthesis
HDL (in moderation)
What's elevated in the blood of a person with familial hypertriglyceridemia?
What is the function of IDL?
Delivers cholesterol and TG to the LIVER
What is mechanism for uptake of LDL?
Binds LDL receptors in periphery via B-100 and undergoes receptor-mediated endocytosis
What's elevated in the blood of a person with familial hypercholesterolemia?
LDL and cholesterol
Which lipoproteins are found on VLDL?
ApoE, ApoC-II, ApoB-100
ApoC-II is found on which particles?
Chylomicrons, VLDL, and HDL
What's the cause of familial hypercholesterolemia?
Absent or defective LDL receptors
Pancreatitis in a non-alcoholic
Familial hypertriglyceridemia, familial hyperchylomicronemia, hypercalcemia
Function of ApoA-I
Activates LCAT (which esterifies cholesterol)
Mode of inheritance:
Describe the transport of HDL
Nascent HDL particles released by the liver and intestine --> acted on by LCAT which esterifies cholesterol --> forms mature HDL --> goes back oto the liver or is acted on by CETP --> transfers cholesterol esters to other lipoprotein particles
ApoB-48 is found on which particles?
Chylomicrons and chylomicron remnants
What proportion of plasma cholesterol is esterified by LCAT to form mature HDL?
Pancreatitis + heptasplenomegaly + eruptive/pruritic xanthomas
Type I familial dyslipidemia
ApoA-I is found on which particles?
Chylomicrons and HDL
What's elevated in the blood of a person with familial hyperchylomicronemia?
Chylomicrons, cholesterol, TG
Describe the transport of dietary fat and cholesterol
Formed into chylomicrons in the small intestine with the aid of bile acids from the liver --> acted on by LPL on surface of vascular endothelium --> releases FFA that go to skeletal muscle and adipose tissue --> chylomicron remnants taken up by liver via chylomicron remnant receptors
Which lipoproteins are found on HDL?
ApoE, ApoA-I, ApoC-II
Secreted from liver only
Secreted from intestine only
Secreted from liver and intestine
Incidence of heterozygous familial hypercholesterolemia?
Which lipoproteins are found on IDL?
What causes familial hypertriglyceridemia?
Hepatic overproduction of VLDL
Describe the transport of cholesterol from the liver to peripheral tissues
VLDL made in and released by the liver into circulation --> acted on by LPL bound to vascular endothelium --> forms FFA + IDL which goes back to the liver or is acted upon by HL --> forms LDL --> taken up by LDL receptors in liver or peripheral tissues
MI at age 20
Homozygous familial hypercholesterolemia
Function of ApoE
Uptake of all remnants except LDL
What is a chylomicron remnant made up of and what is its function?
Cholesterol, most of its TG has been depleted; delivers cholesterol to the liver (uptake via ApoE)
Which lipoproteins are found on chylomicron remnants?
Tendon xanthoma + cholesterol ~ 300 + corneal arcus
Heterozygous familial hypercholesterolemia
What is the function of HDL?
Transports cholesterol from periphery to liver and provides a reservoir of ApoE and ApoC, which are needed for VLDL and chylomicron metabolism
Young non-drinker with pancreatitis that resolves rapidly upon fasting + normal gallbladder US
(TG + pancreatic lipase = FFA in pancreatic capillaries; normally these FFA bind albumin but if TG > 1000 albumin becomes overwhelmed and FFA cause direct damage to pancreas)
How is LDL formed?
Hepatic lipase degradation of IDL TG
Function of HL
Degrades TG remaining in IDL to form LDL
ApoB-100 is found on which particles?
LDL, VLDL, IDL
Tendon xanthoma + cholesterol > 700 + corneal arcus
Homozygous familial hypercholesterolemia
ApoE is found on which lipoprotein particles?
Chylomicrons, chylomicron remnants, HDL, VLDL, IDL
Function of hormone-sensitive lipase
Degrades TG stored in adipose tissue
What is found in lipoprotein particles?
Cholesterol, TG, phospholipids
Transports cholesterol from periphery to liver
Degradation of dietary TG in small bowel
Where is LPL found?
Vascular endothelial surface
What's the cause of familial hyperchylomicronemia?
Defective lipoprotein lipase or ApoC-II (LPL cofactor) = can't degrade TG in chylomicron to for chylomicron remnants for uptake by liver
Transport cholesterol from liver to periphery
Function of ApoB-100
Binds LDL receptor
Function of LPL
Degradation of TG in VLDL or chylomicrons
Which lipoproteins are found on chylomicrons?
ApoE, ApoB-48, ApoA-I, ApoC-II
Which is the only lipoprotein found on LDL?
ApoB-100 (which binds LDL receptor)
No increased risk for atherosclerosis
Function of ApoB-48
Dx if this is a 25-year-old patient?
Familial hypercholesterolemia (type IIa dyslipidemia)
Which two lipoprotein particles carry the most cholesterol?
HDL and LDL