Lipids Metabolism (Lipoprotein)

Question 1

Chylomicrons Source

Answer 1

Intestine

Question 2

VLDL Source

Answer 2

Liver and intestine

Question 3

LDL Source

Answer 3

Chylomicrons and VLDL

Question 4

HDL Source

Answer 4

Liver and intestine

Question 5

NEFA Source

Answer 5

Adipose tissue

Question 6

Chylomicrons PTN %

Answer 6

1-2 %

Question 7

VLDL PTN %

Answer 7

7-10 %

Question 8

LDL PTN %

Answer 8

22 %

Question 9

HDL PTN %

Answer 9

50 % globulin

Question 10

NEFA PTN %

Answer 10

99 % albumin

Question 11

Chylomicrons Main lipid

Answer 11

Exogenous

Question 12

VLDL Main lipid

Answer 12

Endogenous

Question 13

LDL Main lipid

Answer 13

Cholesterol

Question 14

HDL Main lipid

Answer 14

Phospholipids

Question 15

NEFA Main lipid

Answer 15

NEFA

Question 16

CHYLOMICRONS Functions

Answer 16

transport dietary lipids from intestine to peripheral tissues

Question 17

CHYLOMICRONS METABOLISM

Answer 17

1. Intestinal mucosal cells secrete nascent chylomicrons produced primarily from dietary lipid
2. Apo C2 and apo E are transferred from HDL to the nascent chylomicron convert it to mature chylomicrons
3. lipoprotein lipase, activated by C2 , degrades TAG in chylomicrons
4. APO C2 is returned to HDL “Remnant Chylomicron”
5. chylomicrons remnants bind to receptors on the liver where endocytosis

Question 18

VLDL Functions

Answer 18

transport lipids mainly TAG from liver to peripheral tissues

Question 19

apo B48

Answer 19

CHYLOMICRONS

Question 20

apo B100

Answer 20

VLDL

Question 21

VLDL METABOLISM

Answer 21

Liver secretes nascent VLDL lipoprotein particles

Apo C2 and apo E are transferred from HDL to nascent VLDL convert it to mature VLDL

lipoprotein lipase, activated by apo C2 , degrades TAG in VLDL

Apo C2 and apo E are returned to HDL

VLDL to IDL to Liver (endocytosis) & finally to LDL

Question 22

LDL FUNCTION

Answer 22

LDL particles provide cholesterol to peripheral tissues

Question 23

LDL metabolism

Answer 23

LDL apo B100 are recognized by tissue receptors

After binding with receptors, the LDL are internalized by endocytosis

Inside cells LDL are separated from receptors and hydrolyzed by lysosomal enzymes releasing cholesterol, amino acids, fatty acids and phospholipids.

Question 24

HDL Functions

Answer 24

Contain Apo C2, which activates lipoprotein lipase that hydrolyzes TG

Remove cholesterol from peripheral tissues and esterified it by LCAT enzyme → Cholesterol esters

Carry cholesterol esters to VLDL & chylomicrons to the liver

Question 25

HDL metabolism

Answer 25

HDL accepts unesterified cholesterol from peripheral tissues

Then HDL particles (by LCAT enzyme) esterify cholesterol into cholesterol esters

Then HDL is taken up by the liver cells where Cholesterol esters are released inside them to be utilized in the formation of lipoproteins or excreted in bile

Question 26

HDL shape

Answer 26

disk-shape to spherical

Question 27

Reverse cholesterol transport

Answer 27

HDL