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Foundations Of Medicine > Lipids > Flashcards

Lipids Flashcards

1
Q

What are the different lipid classes

A

Fatty acids
Triacylglycerol
Phospholipid
Glycolipid
Steroids

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2
Q

What is the role of lipids in health and disease

A

Imbalance in lipid metabolism can lead to many major clinical conditions including build up of plaque in arteries (atherosclerosis).

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3
Q

Describe fatty acids

A

Saturated no C=C
Unsaturated C=C
Poly-unsaturated 2+ C=C

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4
Q

What is an essential fatty acid

A

FA body cant synthesise
Linoleic and linolenic are essential
Humans cant introduce C=C after C9
Must ingest essential FA

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5
Q

What are non-essential fatty acids

A

FA body is able to synthesise

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6
Q

What are triacylglycerols (TAG)

A

Esters of FAs and glycerol
Esters are neutral uncharged lipids
Water insoluble TAG come together into lipid droplets in adipose tissue (major lipid component of adipose tissue)
Dietary fuel and insulation

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7
Q

Describe phospholipids

A

Amphipathic
Critical for aqueous/non-aqueous interfaces:
Membranes
Lipid droplets
Local signalling molecules

Glycerol bonded to two fatty acids and phosphate group

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8
Q

Descirbe sterols

A

Cholesterol - bile salts, steroid hormones, other components
Steroid hormones - chemical messengers in body
Bile salts - sodium salts of steroids used for emulsification

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9
Q

Describe cholesterol

A

Component of cell membrane, precursor to other substances
Made in liver mainly
Found in animal products

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10
Q

What is the function of bile salts

A

Biological detergents form emulsions and mixed micelles
Prevents lipids coalescing in aqueous environment

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11
Q

Describe Eicosanoids

A

Lipid class from 20-carbon unsaturated FA
Signaling molecules derived from omega-3 or 6 FA
Precursor to prostaglandins, thromboxanes, and leukotrienes

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12
Q

Describe the digestion of lipids

A

TAG main dietary lipid
phospholipids, cholesterol, cholesterol ester, free fatty acids
Small intestine
Digestion by pancreatic lipases, promoted by emulsification by bile salts and peristalsis (mixing)

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13
Q

What are the products of digestion

A

TAG - monoacylglycerol and two FA
Cholesterol esters - cholesterol and free FA
Phospholipids - FA and lysophospholipid

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14
Q

Describe FA absorption

A

Long chain FA form mixed micelles with bile salts. Mixed micelles approach brush border, release lipid products which enter cells by diffusion.
Short/medium chain dont need micelles

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15
Q

What happens to absorbed Fatty acids

A

FAs are insoluble
Packaged with apoB-48 (solubilising protein) into chylomicrons for export
Chylomicrons released by exocytosis into lymph then blood

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16
Q

What happens when blood chylomicrons reach tissue

A

Lipoprotein lipase hydrolyse FA and glycerol from TAG in Chylomicrons
In skeletal muscle/adipose tissue capilaries
Free FA used for energy or re-esterified to TAG for storage
Chylomicron remnants have no TAG and go to liver
Glycerol used by liver to make glycerol-3-phosphate (glycolysis & gluconeogenesis)

17
Q

How are fatty acids transported

A

Free FA - Through blood in complex with serum albumin
Esterified FA - In lipoproteins

18
Q

What is the structure of lipoproteins

A

Hydrophobic cores - TGs, cholesterol esters
Hydrophilic surfaces - Unesterified cholesterol, phospholipids, apolipoproteins e.g.B100

19
Q

What are different lipoprotein classes

A

Classified by density
Chylomicrons - TAG rich (intestine to tissue)
VLDL - TAG rich (liver to tissue)
LDL - Cholesterol rich (extrahepatic tissue, outside liver)
HDL - Protein & cholesterol rich (tissue to liver for elimination)
Increasing density

20
Q

What happens to excess carbs and carbon from proteins

A

Stored as fatty acid residues of TAG in adipose tissue

Involves metabolism through acetyl CoA.

21
Q

What is fatty acid synthase

A

Enzyme for FA synthesis
Liver, lactating mammary gland, adipose tissue and kidney
Occurs in cytosol

22
Q

Describe catabolism of fatty acids by beta-oxidation

A

Mitochondrial pathway
2-carbon fragments successively removed from carboxyl end of fatty acyl CoA, producing acetyl CoA
Oxidation coupled to reduction of FAD and NAD.
Acetyl CoA can be metabolised through CAC

23
Q

What are ketone bodies

A

Water soluble compounds
Produced when Liver mitochondria divert excess acetyl CoA from FA or pyruvate oxidation

24
Q

What is the function of ketone bodies

A

Energy source while fasting
In periphreal tissue may be re-converted into acetyl CoA and metabolised aerobically

25
Q

What is ketosis

A

Concentrations of ketone bodies in blood may increase abnormally
When large amounts of TAGs are being mobilised in starvation and untreated diabetes mellitus

Foundations Of Medicine (28 decks)

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