Biochem--Lipids And Lipoproteins

Front 1

Dietary lipids are comprised of what?

Back 1

-triglycerides (esterfied FAs)
-unesterified FAs (free fatty acids)
-cholesterol
-cholesteryl esters
-phospholipids

Front 2

Lingual and gastric lipases catalyze the digestion of what?
-what are they important for?

Back 2

triglycerides containing fatty acids with SHORT-or MEDIUM CHAIN length
-they are acid-stable enzymes
-important in lipid digestion
(neonates-milk fat, and cystic fibrosis-no pancreatic lipase)

Front 3

Emulsification is necessary for what?

Back 3

further digestion or digestion of TG with FAs of LONG-CHAIN

Front 4

What is emulsification?

Back 4

-increases surface area of lipid droplets for better digestion
(NOT digestion--> breakdown by enzymes)

Front 5

What is emulsification facilitated by?

Back 5

bile salts
peristalsis

Front 6

Bile salts are produced and stored where?

Back 6

produced by the liver from cholesterol
stored in the gallbladder

Front 7

What hormone stimulates the release of bile salts by the gallbladder?

Back 7

cholecystokinin
(sense the presence of fats)

Front 8

Lipid Malabsorption can result from what 2 things?

Back 8

cystic fibrosis
-malfunction of exocrine cells of liver, pancreas, gallbladder

shortened bowel

Front 9

Steatorrhea

Back 9

-chronic diarrhea and weight loss because of lipid malabsorption
-with no lipid absorption, fat soluble vitamins and dietary lipids would be excreted in the feces

Front 10

What are chylomicrons? made of?

Back 10

-82% triacylglycerols
-7% phospholipids
-9% cholesterol and cholesterol esters

Front 11

What are chylomicrons packaged in?

Back 11

-apolipoprotein B-48

Front 12

abetalipoproteinemia

Back 12

-absence of MTP
(microsomal triglyceride transfer protein: bind lipids to apoB-48)
-absence of chylomicrons in plasma
-autosomal recessive severe neuropathy

Front 13

What does ApoC2 do?

Back 13

acts as activator of lipoproteinb lipase (LPL)

Front 14

LPL is primarily secreted by what?

Back 14

-adipocytes (for FA storage)
-muscle cells (FA for energy-ATP)

LPL of adipose=high Km (low affinity)
LPL of muscle=low Km (high affinity)

Front 15

Diabetes mellitus:

Back 15

low or absent insulin
--> low LPL and high conc. of hormone-sensitive lipase
--> hypertriacylglycerolemia

Front 16

Familial lipoprotein lipase deficiency
(type 1 hyperlipoproteinemia)

Back 16

-autosomal recessive disorder
-resulting in massive CHYLOMICRONEMIA
(lot of chylomicrons that stay in the blood)

Front 17

What are the remaining chylomicron components?

Back 17

-cholesteryl esters (CE)
-Phospholipids (P)
-apolipoproteins (Apo)
-a few triacylglycerols

Front 18

What happens to the remnants of chylomicrons?

Back 18

-they bind to receptors on hepatocytes: Apo E on chylomicron remnant recognized)
(LDL receptor-related protein LRP)
-endocytosed by the LIVER cells with receptors for hydrolysis in lysosomes

Front 19

Type III hyperlipoproteinemia
dysbetalipoproteinemia

Back 19

compromised removal of chylomicron remnants by the liver results in their accumulation in the plasma

Front 20

carbohydrate induced hypertriglyceridemia

Back 20

fatty acids + glycerol --> TG
high carbohydrates intakes

Front 21

MTP (microsomal triglyceride transfer protein) facilitates binding of 2 things

Back 21

-binding of lipids to Apo 48 in chylomicrons
-binding of TG to apoB100 in VLDL

Front 22

Lipogenesis

Back 22

synthesis of TGs from glucose
-synthesis of FAs from glucose occurs in the liver
-FAs + glycerol (from glucose)
---> packaged by apoB100 in VLDL
---> secreted into the blood

Front 23

Fatty liver/hepatic steatosis

Back 23

occurs when triglycerides in the liver are higher than those secreted as VLDL

-VLDLs are produced in the liver
-they transport triacylglycerol from liver to peripheral tissue

Front 24

type II hyperlipidemia
(familial hypercholesterolemia)

Back 24

-deficiency in functional LDL receptors

(this can also cause premature atherosclerosis)
-you get more cholesterol in the blood because it cannot get into the liver for degradation

Front 25

What does thyroid hormone, T3 do?

Back 25

stimulates binding of LDL to its receptors

Front 26

Wolman disease

Back 26

-deficiency in enzymes for cholesteryl esters hydrolysis

Front 27

Niemann-Pick disease, type C

Back 27

-deficiency in releasing cholesterol from lysosomes

Front 28

What does HDL transport from tissues to liver?

Back 28

esterified cholesterol from tissues to the liver

Front 29

What does Orlistat do?

Back 29

orlistat=anti obesity drug
-inhibites lipases-->undigested lipids-->fat malabsorption-->weight loss
(it does not inhibit absorption...that is just a consequence of the undigested lipids)

Front 30

What is colipase?

Back 30

it is a pancreatic enzyme that binds to lipases for better lipid digestion

Front 31

Where does the synthesis of complex lipids occur in the cell?

Back 31

endoplasmic reticulum of enterocytes

Front 32

What happens to the short and medium chain FAs that are absorbed into the enterocyte?

Back 32

they are released in the blood where they are solubilized and transported to the liver by ALBUMIN

Front 33

what are the major components of chylomicrons?

Back 33

triacylglycerols

Front 34

Tangier disease
(familial high-density lipoprotein disease)

Back 34

deficiency of HDL