Lipids

Question 1

What do lipids exist as in adipose tissue?

Answer 1

lipid droplets

Question 2

What do lipids exist as in blood?

Answer 2

lipoproteins

Question 3

What is the structure of fatty acids?

Answer 3

Hydrophobic hydrocarbon ‘tail’ and hydrophilic terminal carboxyl group

Question 4

What is the name of the lipid class that gives rise to blood group antigens?

Answer 4

glycolipids (consitituent of membranes)

Question 5

What makes a fatty acid unsaturated?

Answer 5

has one or more double bonds that kink the hydrocarbon chain, liquid

Question 6

What are examples of essential fatty acids?

Answer 6

linoleic and alpha linolenic acid

Question 7

What are good fatty acids?

Answer 7

high in polyunsaturated fatty acids

Question 8

What are bad fatty acids?

Answer 8

high in saturated fatty acids

Question 9

What are really bad fats?

Answer 9

trans fatty acids resulting from hydrogenation of vegetable oils

Question 10

What is linoleic acid a substrate for?

Answer 10

prostaglandins and arachidonic acid which is a precursor of eicosanoids (signalling molecule)

Question 11

What is linolenic acid a substrate for?

Answer 11

omega 3 fatty acids

Question 12

What do omega 3 fatty acids do?

Answer 12

lower plasma cholesterol preventing atherosclerosis and lowers TAG preventing obesity

Question 13

What are triacylglycerols?

Answer 13

esters of fatty acids and glycerol which are uncharged and water insoluble therefore form droplets

Question 14

What do TAGs do?

Answer 14

dietary fuel and insulation

Question 15

What are phospholipids composed of?

Answer 15

2 fatty acids and glycerol and a phosphate group

Question 16

What does ‘amphipathic’ mean?

Answer 16

Has both hydrophilic and hydrophobic parts

Question 17

What is the main dietary lipid?

Answer 17

TAG

Question 18

Where is the main site of lipid digestion?

Answer 18

small intestine

Question 19

What enzymes digest lipids?

Answer 19

lipases

Question 20

What is lipid digestion promoted by?

Answer 20

emulsiification by bile salts and peristalsis

Question 21

What do bile salts do?

Answer 21

act as biological detergents to form emulsions and mixed micelles
are derivatives of cholesterol
saves lipids coalescing in an aqueous environment

Question 22

How do we digest TAG?

Answer 22

degraded in small intestine by pancreatic lipase to monoacylglycerol and 2 fatty acids as is too big to be taken up by mucosal cells in intestinal villi

Question 23

What are cholesterol esters digested to?

Answer 23

cholesterol and free fatty acid

Question 24

What are phospholipids hydrolysed to?

Answer 24

FA and lysophospholipid

Question 25

How are digested lipids absorbed?

Answer 25

products form mixed micelles with bile salts | mixed micelles approach brush border membranes of enterocytes and release lipid products which enter cells by diffusion

Question 26

What FAs don't need micelles for absorption?

Answer 26

short and medium chain FAs

Question 27

What is steatorrhea?

Answer 27

excess fat in faeces due to lipid malabsorption

Question 28

What patients are prone to developing steatorrhea?

Answer 28

cystic fibrosis affected patients

Question 29

What are 2 possibilities of the utilisation of dietary lipids after fatty acids are absorbed?

Answer 29

intestinal cells resynthesises TAG, phospholipid, cholesterol ester for export or are packaged into chylomicrons to make them soluble and released into lymph by exocytosis and then into blood

Question 30

What does lipoprotein lipase do?

Answer 30

hydrolyses TAG in chylomicrons to FA and glycerol

Question 31

Where is lipoprotein lipase mainly found?

Answer 31

in capillaries of skeletal muscle and adipose tissue

Question 32

Where do chylomicron remnants go?

Answer 32

liver

Question 33

What is glycerol in the liver used to do?

Answer 33

produce glycerol-3-phosphate which can be used in glycolysis and gluconeogenesis

Question 34

How are FAs released from stored TAG in tissues?

Answer 34

Hormone sensitive lipase (HSL)

Question 35

What is HSL activated by?

Answer 35

phosphorylation in response to epinephrine

Question 36

How are free FAs transported in the blood?

Answer 36

lipoproteins | in complex with serum albumin

Question 37

What do chylomicrons carry and from where to where?

Answer 37

TAG | intestine to tissues

Question 38

VLDL carry and to where?

Answer 38

TAG | liver to tissue

Question 39

LDL

Answer 39

cholesterol | to tissues

Question 40

HDL

Answer 40

cholesterol | tissue to liver for elimination