Lipids (Part 2)

Question 0

The specific site in the intestine where chylomicrons are assembled in the exogenous pathway

Answer 0

intestinal epithelial cells

Question 1

Three important pancreatic enzymes and their substrates in the exogenous pathway for dietary lipids

Answer 1

Lipase, cholesterol esterase, and phospholipase A

Question 2

The importance of mixed micelle formation in the absorption of dietary cholesterol in the exogenous pathway

Answer 2

bile acids act as detergents; helps to transport cholesterol easily to epithelial cells to be absorbed

Question 3

The importance of apolipoprotein C-II and lipoprotein lipase for triglyceride hydrolysis in exogenous pathway

Answer 3

C-II activates lipoprotein lipase causing rapid hydrolysis of TGL into free fatty acids to be taken up by adipose or muscle cells

Question 4

Disposition of fatty acids after TGL hydrolysis in exogenous pathway

Answer 4

free fatty acids combine with ALB and are taken up by muscle cells as an energy source or by adipose cells for energy storage as TGL

Question 5

How the cylomicron remnant is formed in the exogenous pathway

Answer 5

what remains of free fatty acids to enter the liver (cholesterol esters) (B-48 and Apo E)

Question 6

The importance of apolipoprotein E for hepatic uptake of the chylomicron remnant in the exogenous pathway

Answer 6

required for hepatic endocytosis (entrance into the liver)

Question 7

The major carrier of exogenous (dietary) lipids

Answer 7

chylomicrons

Question 8

purpose is to transfer hepatic-derived lipids, especially TGLs, to peripheral cells for energy metabolism

Answer 8

endogenous pathway for lipids

Question 9

Major carrier of endogenous (hepatic origin) lipids

Answer 9

VLDL

Question 10

The importance of lipoprotein lipase and apolipoprotein C-II in the formation of the VLDL remnant in the endogenous pathway

Answer 10

C-II activates lipoprotein lipase on the surface of endothelial cells, leading to TGL hydrolysis and free fatty acids release to peripheral cells

Question 11

The formation of IDL in the endogenous pathway

Answer 11

Progressive lipolysis of TGL from the core of VLDL transforms it to intermediate density lipoprotein (IDL)

Question 12

the formation of LDL in the endogenous pathway

Answer 12

IDA transfers Apo E, C, free cholesterol, and phospholipids to HDL in the circulation making LDL

Question 13

The importance of chol ester transfer protein (CETP) in TGL cholesterol exchange

Answer 13

removes TGL from LDL and exchanges it for cholesterol esters from HDL; LDL is rich in cholesterol esters and contain ONLY B-100

Question 14

The importance of the presence of only apolipoprotein B-100 on LDL in the endogenous pathway

Answer 14

B-100 is the receptor protein that allows LDL to bind to hepatic or extrahepatic cells to deliver its cholesterol load

Question 15

mechanism to maintain cholesterol balance; LDL receptors deliver intact particles to lysosomes where cholesterol esters are hydrolyzed by lysosomal acid lipase; associated apolipoproteins are degraded to small peptide and amino acid

Answer 15

Purpose of intracellular-cholesterol transport pathway of lipid metabolism

Question 16

The importance of Apolipoprotein B-100 in the intracellular-cholesterol transport pathway

Answer 16

LDL is recognized by LDL receptor

Question 17

intracellular enzyme responsible for cholesterol ester hydrolysis in the intracellular-chol transport pathway

Answer 17

lysosomal acid lipase

Question 18

Three intracellular uses of cholesterol esterase

Answer 18

membrane biogenesis, stored in intracellular lipid drops after re-esterification by ACAT catalysis

Question 19

The effect of excess intracellular chol on the cell

Answer 19

downgrades HMG-CoA reductase activity, inhibits expression of LDL receptor, induces the synthesis of proteins involved in reverse chol transport

Question 20

Three uses of intracellular chol in hepatocytes

Answer 20

Repackaged and secreted on lipoproteins converted to bile salts; directly secreted into bile

Question 21

Macrophages accumulate excess chol and become these (atherogenic)

Answer 21

Foam Cells

Question 22

Purpose is to remove excess chol from peripheral cells and return it to the liver for excretion; mediated by HDL

Answer 22

reverse cholesterol transport pathway of lipid metabolism and the lipoprotein that mediates it

Question 23

pumps cholesterol out of cells in the reverse-chol transfer pathway

Answer 23

ABCA 1 transporter

Question 24

Why is it important that nascent HDL be converted to its spherical form (HDL2)?

Answer 24

So it can return to circulation to pick up more cholesterol

Question 25

Three hepatic receptors to which HDL may bind to return chol esters back to the liver in reverse chol transfer pathway

Answer 25

LDL receptor, HDL receptor, and Remnant receptor

Question 26

Four reasons why HDL is considered “good” cholesterol

Answer 26

anti-clotting properties, promotion of the efflux of excess cellular chol, antioxidant properties, anti-inflammatory properties