Biochem - Lipid and Cholesterol Flashcards
Chylomicrons
Deliver TGs to peripheral tissue
Deliver cholesterol to liver
VLDL
TG to peripheral tissues – secreted by liver
IDL
By product formed in degradation of VLDL
Deliver TG and cholesterol to liver
ApoB48
Chylomicron secretion from enterocyte to lymphatic system
ApoB100
Found in VLDL, IDL, LDL
Need to leave the liver into circulation
ApoE
Mediates Extra remnant uptake
ApoA1
Activates LCAT
Found on HDL
Apo CII
Cofactor for lipoprotein lipase
Abetalipoproteinemia
AR
Decreased ApoB48 and ApoB100 – chylomicrons can’t leave enterocyte
Mutation MTP gene (microsomal transfer protein)
-> chylomicron and VLDL synthesis and secretion
Steatorrhea: can’t absorb ADEK and fats
Intestinal bx: enterocytes swollen w/ TGs
Peripheral smear: acanthocytosis of RBCs – spikey
Ataxia – vit E
Night blindess – vit A
Tx: vit E helps restore lipoproteins
Draw out lipid transport pathway
Page 553
Draw out HDL transport
Page 553
Type I hyperchylomicronemia
AR
Lipoprotein lipase deficiency or defective ApoCII
Increased chylomicrons, TGs, cholesterol
Present:
Pancreatitis d/t high TGs
HSM
Pruritic xanthomas
No increased risk for atherosclerosis
Type IIa Familial hypercholesterolemia
AD
Absent or low LDL receptors – uptake LDL from blood
Tendinous xanthomas
Corneal arcus
Accelerated atherosclerosis
Homozygous -> MI as young as 20s
Type IV hypertriglyceridemia
AD
High VLDL, high TGs
Overproduction of VLDL in liver
High TG -> pancreatitis
Signs of hypercholesterolemia
Atheroma – oxidized LDL particles, plaque in BV wall
Xanthoma – nodules of histiocytes filled w/ cholesterol
-eyelids – xanthalasma
Tendinous xanthomas – Achilles
Corneal arcus – white ring around iris
Cholesterol synthesis
Acetyl-CoA substrate
Rate limiting enzyme – HMG-CoA reductase
-blocked by statins
Fatty acid synthesis
Precursor acetyl CoA
Cytoplasm of hepatocytes
Rate limiting enzyme: Acetyl-CoA carboxylase
Fatty acid degradation
Mitochondria matrix
- b-oxidation of acetyl CoA into groups
- > ketone body buildup or TCA
Rate limiting enzyme: Carnithine acyltransferase (CAT1) aka Carnitine palmitoyl transferase 1
Carnitine deficiency
Unable to transfer LCFAs to mt
Accumulation of LCFAs in cytoplasm
-> weakness, hypotonia, hypoketotic hypoglycemia
