Cholesterol

Question 1

why is most atp made in mitochondria

Answer 1

where most acetyl-coA is made

Question 2

what are the primary sources of fat

Answer 2

diet
de novo synthesis in the liver
storage depots in adipose

Question 3

properties of bile salts

Answer 3

made in liver, stored in gall bladder
emulsify fats + fat soluble vitamins ADEK
have hydrophobic and hydrophillic sides

Question 4

orlistat

Answer 4

inhibits pancreatic + gastric lipase which reduces fat absorption = weight loss
derivative of lipstatin

Question 5

side effects of orlistat

Answer 5

abdominal pain
urgency to defecate
increased flatus
steatorrhoea

Question 6

what do lipoproteins do

Answer 6

transport lipids in plasma

Question 7

how are chylomicrons made

Answer 7

after enterocytes absorb digestion products in small intestine brush border, triglycerides are resynthesised in golgi and form CMs

need apoproteins from HDL in bloodstream

Question 8

function of chylomicrons

Answer 8

dietary fat transport

Question 9

chylomicron journey

Answer 9

intestinal lacteal => thoracic duct => left subclavian vein => BS

Question 10

what is lipoprotein lipase and what does it do

Answer 10

breaks down triglycerides carried by CMs, allowing fatty acids + glycerol to enter tissues

Question 11

what happens to fatty acids and glycerol

Answer 11

FA: B-ox
G: liver => gluconeogenesis

Question 12

where is lipoprotein lipase found

Answer 12

capillary endothelium lining: adipose/heart/skeletal muscle

Question 13

cholesterol properties

Answer 13

steroid/basis of all steroids

increases/decreases membrane fluidity depending on temp + membrane nature

supplied by liver via de novo synthesis

Question 14

3 main stages of cholesterol formation

Answer 14

1. synthesis of isopententyl pyrophosphate
2. condensation of IPP to form squalene
3. cyclisation and demethylation of squalene to form cholesterol

Question 15

how are bile salts synthesised
(+ name 2 primary bile salts)

Answer 15

cholesterol is broken down by series of reactions

glycholate + taurocholate

Question 16

structure, function + types of lipoproteins

Answer 16

phospholipid monolayer surrounding cholesterol esters and triglycerides

transports hydrophobic lipids in aqueous environment

VLDL, LDL, IDL, HDL

Question 17

formation of cholesterol esters

Answer 17

made in plasma from cholesterol + acyl chain of phosphatidyl-choline

Question 18

HDL

Answer 18

‘good’
cholesterol from tissue to liver for use/disposal (reverse cholesterol transport)
reduces blood cholesterol levels

5% Tg, 20% CE, 30% PL, 8% FreeChol

Question 19

LDL

Answer 19

‘bad’
cholesterol from liver to tissue
increases tissue cholesterol

6% Tg, 42% CE, 22% PL, 8% FreeChol

Question 20

what is familial hypercholesterolaemia

Answer 20

monogenic dominant condition in which serum cholesterol is increased

single mutation = 2-3x = atherosclerosis in middle age

double = 5x = severe atherosclerosis + coronary infarcts in adolesence

Question 21

what are xanthomas

Answer 21

bumps on skin due to deposition of plasma LDL derived cholesterol to macrophages of skin (familial hypercholesterolaemia)

Question 22

FH and fibroblasts

Answer 22

new research: FH = fibroblasts = no functional receptors due to mutates genes
LDL cant be up taken into cytosol so its left in serum

Question 23

what do statins do

Answer 23

inhibit HMG-CoA reductase in step 3 of cholesterol formation

e.g lovastatin

Question 24

what do resins do

Answer 24

binds/sequesters bile acid-cholesterol complexes to prevent reabsorption in intestine
lowers LDL + increases HDL

e.g cholestryamine