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Flashcards in Cholestrol Deck (43)
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1
Q

Where is fat derived from?

A

Diet, De novo biosynthesis, Storage depots in adipose.

2
Q

What enzyme breaks down dietary fat?

A

Lipases

3
Q

What do bile salts do?

A

They emulsify fats in the intestine.

4
Q

Why are bile salts needed?

A

The aid digestion and absorption of fats and fat soluble vitamins.

5
Q

Where are bile salts generated and stored?

A

Generated in liver and stored in gallbladder.

6
Q

What is steatorrhea?

A

Fatty stool caused by undigested fat and unabsorbed fat.

7
Q

What can cause steatorrhea?

A

Lack of bile salts.

8
Q

What is orlistat?

A

A drug that inhibits gastric and pancreatic lipases.

9
Q

What is orlistat used to treat?

A

Obesity.

10
Q

Side effects of orlistat?

A

Steatorrhea, abdominal pain, urgency to defecate.

11
Q

Why are lipids transported as lipoproteins?

A

Lipids are hydrophobic and so to transport in aqeuous plasma they have to be transported within proteins.

12
Q

VLDL role?

A

Endogenous fat transport

13
Q

HDL role

A

Reverse cholesterol transport

14
Q

What type of cell absorbs products of digestion?

A

Enterocytes

15
Q

Chylomicron pathway?

A

Triglycerides incorporated in chylomicron. Transported via lymphatics. Enters bloodstream. Acquires apoproteins from HDL.

16
Q

What allows chylomicrons to be detected in the blood stream?

A

Apoproteins

17
Q

How are contents of chylomicron accessed?

A

Lipoprotein lipase binds to apoprotein and breaks down chylomicron to take in contents.

18
Q

Where is lipoprotein lipase found?

A

Capillary endothelial cells.

19
Q

What happens to fatty acids in metabolism?

A

Undergo B oxidation.

20
Q

What happens to glycerol?

A

Used for gluconeogenesis.

21
Q

What makes up a chylomicron?

A

Triacylglycerols, phospholipids and apoprotein.

22
Q

Where does the chylomicron get its apoproteins from?

A

HDL.

23
Q

What is the point of chylomicrons?

A

To transport dietary fat.

24
Q

What is cholesterol?

A

A steroid found in cell membranes.

25
Q

What does cholesterol do?

A

Alter membrane stiffness depending on temperature and nature of membrane.

26
Q

How is most cholesterol made?

A

de novo synthesis from acetyl CoA.

27
Q

Where is most cholesterol made?

A

Liver.

28
Q

What is the significance of pregnenolone?

A

All 5 classes of steroid hormone come from it.

29
Q

What enzyme catalyses the conversion of cholesterol to pregnenolone?

A

Desmolase.

30
Q

What molecules can be made from cholesterol?

A

Pregnenolone, Vitamin D and Bile salts (cholesterol breakdown).

31
Q

Describe the structure of a lipoprotein

A

Phospholipid monolayer containing cholesterol and apoproteins surrounding core of triacylglycerols and cholesterol esters.

32
Q

Where are cholesterol esters produced and how?

A

Produced in the plasma by transfer of an acyl chain from phosphatidylcholine (lecithin) catalyzed by lecithin:cholesterol acyltransferase.

33
Q

What is reverse cholesterol transport?

A

Cholesterol from peripheral tissues back to liver.

34
Q

How are LDL’s formed?

A

Addition of cholesterol esters to IDL (intermediate lipoprotein) from HDL to form LDL.

35
Q

What removes LDL from bloodstream?

A

Liver and macrophages.

36
Q

Explain lipoprotein transport pathways.

A

Liver produces VLDL which transports fatty acids produced in the liver to tissues to become a lipid depleted remnant. The remnant then loses its apoprotein to HDL and become IDL which gets cholesterols esters from HDL to form LDL. LDL then transports cholesterol to tissues and is uptaken by macrophages or the liver. HDL is involved in reverse cholesterol transport and takes cholesterol from tissues back to liver.

37
Q

Prolonged elevated levels of LDL can lead to?

A

Atherosclerosis.

38
Q

What kind of disorder is familial hypercholesterolaemia?

A

Monogenic dominant trait

39
Q

Problems associated with familial hypercholesterolaemia?

A

More susceptible to atherosclerosis in middle age.

40
Q

What affects how bad familial hypercholesterolaemia?

A

Whether the individual has one or two copies of the mutant gene.

41
Q

Familial hypercholesterolaemia mechanism?

A

Defect in gene that codes for LDL receptor.

42
Q

How do statins work?

A

They reduce total cholesterol by inhibiting HMG-CoA reductase.

43
Q

How do resins work?

A

Bind to bile acid cholesterol complexes preventing their reabsorption by the intestine.