Lipids Flashcards

1
Q

What do lipids exist as in adipose tissue?

A

lipid droplets

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2
Q

What do lipids exist as in blood?

A

lipoproteins

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3
Q

What is the structure of fatty acids?

A

Hydrophobic hydrocarbon ‘tail’ and hydrophilic terminal carboxyl group

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4
Q

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

A

glycolipids (consitituent of membranes)

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5
Q

What makes a fatty acid unsaturated?

A

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

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6
Q

What are examples of essential fatty acids?

A

linoleic and alpha linolenic acid

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7
Q

What are good fatty acids?

A

high in polyunsaturated fatty acids

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8
Q

What are bad fatty acids?

A

high in saturated fatty acids

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9
Q

What are really bad fats?

A

trans fatty acids resulting from hydrogenation of vegetable oils

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10
Q

What is linoleic acid a substrate for?

A

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

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11
Q

What is linolenic acid a substrate for?

A

omega 3 fatty acids

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12
Q

What do omega 3 fatty acids do?

A

lower plasma cholesterol preventing atherosclerosis and lowers TAG preventing obesity

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13
Q

What are triacylglycerols?

A

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

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14
Q

What do TAGs do?

A

dietary fuel and insulation

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15
Q

What are phospholipids composed of?

A

2 fatty acids and glycerol and a phosphate group

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16
Q

What does ‘amphipathic’ mean?

A

Has both hydrophilic and hydrophobic parts

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17
Q

What is the main dietary lipid?

18
Q

Where is the main site of lipid digestion?

A

small intestine

19
Q

What enzymes digest lipids?

20
Q

What is lipid digestion promoted by?

A

emulsiification by bile salts and peristalsis

21
Q

What do bile salts do?

A

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

22
Q

How do we digest TAG?

A

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

23
Q

What are cholesterol esters digested to?

A

cholesterol and free fatty acid

24
Q

What are phospholipids hydrolysed to?

A

FA and lysophospholipid

25
How are digested lipids absorbed?
products form mixed micelles with bile salts | mixed micelles approach brush border membranes of enterocytes and release lipid products which enter cells by diffusion
26
What FAs don't need micelles for absorption?
short and medium chain FAs
27
What is steatorrhea?
excess fat in faeces due to lipid malabsorption
28
What patients are prone to developing steatorrhea?
cystic fibrosis affected patients
29
What are 2 possibilities of the utilisation of dietary lipids after fatty acids are absorbed?
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
30
What does lipoprotein lipase do?
hydrolyses TAG in chylomicrons to FA and glycerol
31
Where is lipoprotein lipase mainly found?
in capillaries of skeletal muscle and adipose tissue
32
Where do chylomicron remnants go?
liver
33
What is glycerol in the liver used to do?
produce glycerol-3-phosphate which can be used in glycolysis and gluconeogenesis
34
How are FAs released from stored TAG in tissues?
Hormone sensitive lipase (HSL)
35
What is HSL activated by?
phosphorylation in response to epinephrine
36
How are free FAs transported in the blood?
lipoproteins | in complex with serum albumin
37
What do chylomicrons carry and from where to where?
TAG | intestine to tissues
38
VLDL carry and to where?
TAG | liver to tissue
39
LDL
cholesterol | to tissues
40
HDL
cholesterol | tissue to liver for elimination