Dietary Fats and Blood Lipids

Question 1

what are lipids?

Answer 1

group of organic substances soluble in organic solvent and virtually insoluble in water

Question 2

what are the 3 main classes of lipids?

Answer 2

cholesterol
triglycerides
phospholipids

Question 3

why is it important cholesterol allows the synthesis of bile acids?

Answer 3

allows absorption of fat soluble vitamins (A,D,E,K)

Question 4

what is the role of cholesterol?

Answer 4

-component of all cell membranes
-synthesis of bile acids
-precursor for endogenous Vit D production
-precursor for steroid hormones

Question 5

which steroid hormones is cholesterol a precursor for?

Answer 5

-oestrogen and progesterone
-testosterone
-cortisol
-aldosterone

Question 6

what is the use of triglycerides?

Answer 6

used as an energy source in tissues
used for energy storage in adipose tissue
essential role but too much can increase risk of heart disease

Question 7

what is a lipoprotein?

Answer 7

-complex spherical structure
-central core of hydrophobic lipids (triglycerides and cholesterol esters)
-surface layer of polar components (phospholipids, free cholesterol, proteins- the apolipoproteins)

Question 8

what is the lipoprotein system?

Answer 8

evolved to solve the problem of transporting fats in the aqueous environment of plasma

Question 9

what are the types of lipoprotein found in the body? (least dense to most dense)

Answer 9

-chylomicron
-VLDL
-LDL
-HDL

Question 10

what is the function of chylomicron?

Answer 10

synthesised in then gut after a meal
main carrier of dietary triglyceride

Question 11

what Is the function of VLDL?

Answer 11

synthesised in the liver
main carrier of endogenously produced triglyceride

Question 12

what is the function of LDL?

Answer 12

generated from VLDL in the circulation
main carrier of cholesterol

Question 13

what is the function of HDL?

Answer 13

returns cholesterol from ectrahepatic tissues to the liver for excretion

Question 14

what are apolipoproteins?

Answer 14

-amphiphilic compounds
-hydrophobic region interacting with lipid core
-provides structure to the lipoprotein
-hydrophilic region interacting with aqueous environment

Question 14

what is the role of apolipoproteins?

Answer 14

play a crucial role in lipid metabolism
-guiding the formation of lipoproteins
-acting as ligand for lipoprotein receptors
-sering as activators or inhibitors of enzymes involved in the metabolism of lipoproteins

Question 15

which apoprotein binds with LDL receptors to allow cholesterol to get inside the cells?

Answer 15

APOB100

Question 16

what happens during the exogenous cycle?

Answer 16

-food is ingested and dietary lipid is absorbed
-goes into the circulation as chylomicron (big and fluffy)
-acted on by lipoprotein lipase to form chylomicron remnants which are then taken up by the liver

Question 17

what connects the exogenous and endogenous cycles?

Answer 17

liver

Question 18

what is cardiovascular disease?

Answer 18

circulation - ischaemic heart disease (angina, myocardial infarction
cerebral circulation - stroke
peripheral circulation - peripheral vascular disease
premature CVD - males onset CVD<55, females onset CVD<65

Question 19

what happens during the endogenous cycle?

Answer 19

liver produces very LDL particles
-relessed into circulation
-broke into IDL
-broke down further into LDL
-can either circulate back and be taken up by LDL receptors in liver or extra hepatic cells

Question 20

what happens when there is too much LDL or LDL is oxidised (those who smoke)?

Answer 20

oxidised LDL taken up more readily by scavenger cells or macrophages and result in the laying down of fatty plaques in the arteries

Question 21

what is the criteria for individuals who are known to be at high risk of CVD?

Answer 21

-those already diagnosed
-chronic kidney disease (stage 3+)
-diabetics >40 or with >20 years with the disease
-evidence of diabetes related organ damage
-those with familial hypercholesterolaemia

Question 22

what are some diabetes related organ damage examples?

Answer 22

eyes - retinopathy
kidneys - proteinuria
nerves - autonomic neuropathy

Question 23

what results can we get from a lipid profile?

Answer 23

-cholesterol
-triglycerides
-HDL cholesterol
-LDL cholesterol
-VLDL cholesterol
-Chol/HDL ratio

Question 24

which cholesterol is lowered by drugs we use?

Answer 24

LDL

Question 25

how much energy does fat contain?

Answer 25

9kcal

Question 26

what kinds of food are high in saturated fat?

Answer 26

pastry coconut oil hard cheese soured cream

Question 27

what kind of foods are high in mono-unsaturated fat?

Answer 27

avocado olives rapeseed oil walnuts

Question 28

what kind of foods are high in poly-unsaturated fat?

Answer 28

salmon rapeseed oil walnuts

Question 29

what are the 3 main lipids carried in the blood stream?

Answer 29

triglycerides cholesterol phospholipids

Question 30

how are lipids transported in the blood and why?

Answer 30

carried in lipoproteins as they are insoluble in blood and water

Question 31

where is HDL and VLDL synthesised?

Answer 31

mainly in the liver

Question 32

where is chylomicron mainly synthesised?

Answer 32

gut after eating

Question 33

where is LDL synthesised?

Answer 33

generated from VLDL In circulation

Question 34

what is HDL?

Answer 34

protective- takes cholesterol from tissues to liver for extraction

Question 35

what is the function of VLDL?

Answer 35

carry triglyceride from liver to skeletal muscle

Question 36

what is the function of LDL?

Answer 36

carry cholesterol from liver (via VLDL) to tissues

Question 37

what is the function of chylomicron?

Answer 37

carry dietary fat from gut to adipose tissue and muscle

Question 38

where is cholesterol absorbed in the GI tract?

Answer 38

small intestine

Question 39

what enzyme hydrolyses VLDL to form IDL?

Answer 39

lipoprotein lipase

Question 40

how can LDL be removed from the circulation?

Answer 40

b high affinity LDL receptors into cells or by scavenger routes (when LDL levels are high) into macrophages leading to atheromatous plaques

Question 41

what happens to the risk of CHD as total cholesterol concentrations increase?

Answer 41

total cholesterol - higher CHD risk is associated with increasing total cholesterol HDL cholesterol - higher HDL is associated with lower CDH risk triglycerides - high triglyceride levels are associated with higher CHD risk

Question 42

what is the mechanism of CHD?

Answer 42

-high conc of LDL, LDL particles more likely to become oxidised and taken up at a fast, uncontrolled rate by scavenger receptors on macrophages -this leads to formation of foam cells which develop into fatty streaks and subsequently atheromatous plaques leading to narrowing of the coronary arteries

Question 43

what is the HDL and CHD risk?

Answer 43

HDL is involved in the reverse cholesterol pathway. It carries cholesterol from tissues back to the liver where it is excreted. Thus, there is less cholesterol in the blood to become oxidised, leading to fewer foam cells and atherosclerotic plaques

Question 44

what is the triglycerides and CHD risk?

Answer 44

High triglyceride levels lead to low HDL concentrations. High triglyceride levels are associated with small, dense LDL particles which are more susceptible to oxidation. The end products of triglyceride-rich lipoproteins can damage the endothelial lining in the arteries, promoting deposition of cholesterol in the artery walls.

Question 45

a patient has a triglyceride level of 14mmol/L what condition are they at risk of?

Answer 45

pancreatitis

Question 46

do triglyceride levels increase or decrease after eating?

Answer 46

higher

Question 47

what is the target cholesterol level after a heart attack?

Answer 47

<3mmol/L

Question 48

what type of fat can increase blood LDL cholesterol concentrations?

Answer 48

saturated

Question 49

what risk calculators can be used to help estimate CV risk?

Answer 49

ASSIGN, QRISK3