Lipid metabolism

Question 1

Where are chylomicrons formed?

Answer 1

small intestine

Question 2

What are Lipo proteins made up of?

Answer 2

Composed of triglyceride, cholesterol ester (in inner core) + cholesterol, phospholipids, apolipoproteins (eg. apo-AI, -B48, -CI, -D, -E) in outer layer

Question 3

_____ density lipoprotein (VLDL)

_____ density lipoprotein (IDL) / VLDL remnants

Answer 3

Very low (VLDL)

Intermediate (IDL)

Question 4

____density lipoprotein (LDL)

____density lipoprotein (HDL)

Answer 4

Low (LDL)

High (HDL)

Question 5

Most lipids are transported in the blood in combination with proteins as______

(Note non polar lipids in centre)

Answer 5

Lipoproteins

Question 6

Which organ removes Chylomicron remnants?

Answer 6

liver

Question 7

ROLES OF CHOLESTEROL?

Answer 7

Synthesis of membranes (stabilizes membranes especially plasma membrane)

Synthesis of bile acids (needed for digestion)

Synthesis of steroid hormones (e.g. androgens)

Synthesis of Vitamin D in skin from 7-dehydrocholesterol & UVB light.

Question 8

Where do Excess LDL particles accumulate?

Answer 8

Excess LDL particles accumulate in artery wall and are chemically altered

Question 9

What are the chylomicrons triglyceride fatty acids used for?

Answer 9

Used by muscle cells for ATP production

Question 10

What type of type of triglycerides do VLDLs contain?

Answer 10

endogenous triglycerides.

Question 11

What are VLDLs role?

Answer 11

They are transport vehicles that carry triglycerides synthesized in hepatocytes to adipocytes for storage.

Question 12

What percentage of total blood cholesterol do LDLs deliver to cells throughout the body?

Answer 12

75%

Question 13

Where do LDLs deposit cholesterol when present in excessive numbers?

Answer 13

smooth muscle fibers in arteries

Question 14

What are HDLs role?

Answer 14

HDLs remove excess cholesterol from body cells and transport it to the liver for elimination (reverse cholesterol transport).

Question 15

APOLIPOPROTEINS TYPES:

Answer 15

Apo A-I, Apo A-II, Apo A-IV

Apo B-48, Apo B-100

Apo C-I, Apo C-II, Apo C-III

Apo D

Apo E

Apo(a)

(Note Apo B is an integral apolipoprotein whereas the others are peripheral apolipoproteins)

Question 16

ROLE OF APOLIPOPROTEINS:

Answer 16

Solubilizes highly hydrophobic lipids (Apo B)

Contains signals (ligands) to regulate movement

Enzyme Cofactors e.g. Apo A-I for lecithin cholesterol acyl transferase (LCAT), Apo C-II for lipoprotein lipase, Apo A-II activates hepatic lipase

Enzyme inhibitors e.g. Apo A-II & Apo C-III for lipoprotein lipase, Apo C-I for cholesteryl ester transfer protein

Lipid Transfer Protein

Question 17

ROLES OF CHOLESTEROL

Answer 17

Synthesis of membranes (stabilizes membranes especially plasma membrane)

Synthesis of bile acids (needed for digestion)

Synthesis of steroid hormones (e.g. androgens, oestrogens, progesterone, glucocorticoids & mineralocorticoids)

Synthesis of Vitamin D in skin from
7-dehydrocholesterol & UVB light.

Question 18

What are the four classes of lipoproteins?

Answer 18

Chylomicrons
VLDLs
LDLs
HDLs

Question 19

How are VLDLs converted to LDLs?

Answer 19

via IDL

Question 20

What is the order of lipoproteins with relation to increasing density? Starting with least dense.

Answer 20

chylomicron, VLDL, IDL, LDL, HDL

Question 21

What is the order of lipoproteins with relation to increasing diameter? Starting with smallest diameter

Answer 21

HDL, LDL, IDL, VLDL, chylomicron

Question 22

What is the order of lipoproteins with relation to increasing protein content ? starting with the smallest protein content.

Answer 22

chylomicron, VLDL, IDL, LDL, HDL

Question 23

What is the order of lipoproteins with relation to increasing TG content ? Starting with the smallest TG content.

Answer 23

HDL, LDL, IDL, VLDL, chylomicron

Question 24

How is Atherosclerotic Plaque Formed?

Answer 24

Excess LDL particles accumulate in artery wall and are chemically altered

Question 25

What does Modified LDL attract and stimulate?

Answer 25

Modified LDL stimulate endothelial cells to attract monocytes & T cells to intima

Question 26

Monocytes become macrophages. T cells and macrophages secrete ______

Answer 26

cytokines

Question 27

Macrophages feast on LDLs and become_______ and with T cells form fatty streak

Answer 27

Foam cells

Question 28

What does Plaque develop into?

Answer 28

Plaque grows as fatty streak develops into atheroma with a fibrous cap and can restrict blood flow

Question 29

Usually ______ weakens and plaque ruptures and clot forms and may cause eg. unstable angina and myocardial infarction

Answer 29

Cap

Question 30

What are the two major sources of cholesterol in the body?

Answer 30

dietary ingestion (exogenous) and hepatic synthesis (endogenous).