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NUTR 3210 > lipid metabolism > Flashcards

lipid metabolism Flashcards

1
Q

what are the 8 functions of lipids

A
  1. concentrated source of energy (9kcal/g)
  2. palatability of foods & increase satiety
  3. source of essential fatty acids
  4. carrier of fat-soluble vitamins
  5. necessary for growth and development
  6. imports precursors for the production of hormones
  7. affect inflammation and blood clotting
  8. key roles in disease development
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2
Q

what does saturated mean

A

-theres a maximum number fo H atoms within the molecule (only single bonds)

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3
Q

what does unsaturated mean

A
  • there are “missing” H atoms
  • presence of double bonds
  • can be cis or trans
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4
Q

what is the most stable form of unsaturated fatty acids

A

trans

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5
Q

for FA nomenclature, what side does the delta system start at

A

numbering starts from the carboxyl end of fatty acid (C=O OH)

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6
Q

for FA nomenclature, what side foes the omega system start at?

A

numbering starts from the methyl end

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7
Q

diets with ,0.1% linoleum acid result in what?

A

poor skin growth and thickened dry skin

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8
Q

what are two essential fatty acids? why are they essential?

A
  • linoleic acid and alpha linolenic acid

- humans lack the enzymes necessary to insert double bonds beyond the delta-9 position of a fatty acid

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9
Q

what does a n-6 deficiency result in?

A

skin: dermatitis
growth: decreases
reproduction: decreases
CNS: is fine
retinal: is fine

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10
Q

what does a n-3 deficiency result in?

A

skin: is fine
growth: is ok
reproduction: is fine
CNS: reduced IQ
Retinal: decreased visual acuity

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11
Q

how do diseases arise from fatty acids?

A

diseases have been linked to the w-6 and w-3 ratios

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12
Q

what are some examples of eicosanoids?

A

prostaglandins
thromboxjnes
leukotreines

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13
Q

what are eicosanoids

A
  • metabolites of 20-carbon fatty acids (primarily AA and EPA)
  • hormone-like (function locally)
  • plays a role in inflammation, platelet aggregation. blood pressure
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14
Q

describe inflammation, correlating it to W6 and W3

A

W6: pro-inflammatory
W3: anti- inflammatory

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15
Q

where are eicosanoids stored?

A

they’re stored as phospholipids in cell membranes

- never free in the cell

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16
Q

what are triglycerides?

A
  • neutral lipids
  • main dietary lipid
  • major storage form of lipids
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17
Q

what are the functions of TAGS

A
  • lipogenisis (production of fatty acids)
  • lipolysis (releases fatty acids in times of need)
  • transport of lipoproteins
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18
Q

what are the principle functions of phospholipids

A
  • components of membranes
  • source of physiologically active fatty acids for eicosanoid synthesis
  • anchors membrane proteins
  • intracellular signalling
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19
Q

what are the principle functions of sterols

A
  • essential components of membranes

- major precursor (for bile acid production, steroid sex hormone production, and vitamin D synthesis)

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20
Q

describe lipid digestion within the mouth

A
  • lingual lipase (continuously released)
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21
Q

describe lipid digestion within the stomach

A
  • gastric lipase (continually secreted, stable at low pH)
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22
Q

describe how the liver helps lipid digestion

A

the liver makes bile acids- which help digest them

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23
Q

describe how the gallbladder helps lipid digestion

A
  • storage of bile acids

the release of bile is triggered by hormones

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24
Q

describe lipid digestion within the small intestine

A
  • pancreatic enzymes (includes pancreatic lipase, cholesterol, and esterase’s
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25
Q

what are mixed micelles

A

small, spherical complexes containing lipid digestion products (and bile acids)

26
Q

describe how mixed micelles work

A
  • accesses the space between microvilli in the intestine

- excreted bile acids are then reabsorbed in the digestive tract

27
Q

describe the efficiency of enterohepatic circulation

A
  • soluble fibres reduce the efficiency of enterohepatic circulation by holding on to bile acids, which are then secreted in feces
28
Q

how much bile acid is lost within feces?

A

about 5% of bile acids are lost in feces

29
Q

how much bile acid is reabsorbed in the small intestine?

A

about 95% of bile acids are reabsorbed and recycles back to the liver

30
Q

what are the three brush border enzymes?

A
  • pancreatic lipase
  • cholesterol esterase
  • phospholipase
31
Q

how are lipoproteins classified?

A
  1. ratio of lipid:proteins (affect density)

2. specific apolipoprotein (affects receptor interactions

32
Q

what is considered good cholesterol

A

low lipid, high protein (high density lipoprotein)

33
Q

what is the primary transport of dietary lipids

A

chylomicron and remnants

34
Q

when do chylomicron concentrations increase

A

they increase in circulation after a meal

peak between 30min-3hr after eating

35
Q

when/where do chylomicrons enter the system

A

chylomicrons enter the lymphatic system before entering the blood (therefore, dietary lipids are available to adipose and muscle before arriving at the liver)

36
Q

where is lipoprotein lipase located

A

LPL is located on the surface of endothelial cells lining small blood vessels and capillaries

37
Q

what activated LPL

A

lipoprotein lipase is activated by ApoC in chylomicrons

38
Q

what is the function of LPL

A

lipoprotein lipase hydrolyzes the TAG in chylomicrons

39
Q

what are chylomicron remnants

A

they are simply when chylomicrons become TAG-depleted

40
Q

how are chylomicron remnants removed from circulation

A

chylomicron remnants (CR) are removed from circulation through ApoE- mediated interactions with a receptor in the liver

41
Q

what is the main transporter of newly synthesized hepatic TAG

A

VLDL (very low density lipoprotein)

42
Q

where/how is LDL taken up?

A

LDL is taken up by the liver via LOL-receptors (mediated endocytosis)

43
Q

describe the esterification of cholesterol

A

-cholesterol obtained from plasma membranes is esterfied directly on high-density lipoproteins

44
Q

what is reverse cholesterol transport

A

when high-density lipoproteins pick up cholesterol around the body and divert it back to the liver

45
Q

function of lecithin-cholesterol-acyltransferase?

A

LCAT esterfies fatty acids to cholesterol

46
Q

what is SRBI

A 
a scavenger receptor class B1 
(an HDL receptor in the liver)
47
Q

what is CETP

A

cholesterol ester transfer protein

transfers cholesterol from HDL to VLDL and/or LDL

48
Q

what are the three fates of cholesterol within the liver?

A
  1. converted into bile acids to replenish the bile acid pool
  2. secreted “as is” directly with bile (to be excreted in feces)- only if body doesn’t need more bile acids
  3. packaged into VLDL and sent around the body (if in fasted state)
49
Q

function of LDL

A

LDL delivers cholesterol for essential functions but can also deposit cholesterol in unwanted places

50
Q

high HDL levels=?

A

higher HDL levels means more cholesterol returning to the liver

51
Q

where do lipids fit into gluconeogenesis?

A
  • the glycerol backbone is glycogenic (and us used to make glucose in faster states)
52
Q

where do lipids fit into the Krebs cycle

A

fat oxidation via acetyl coA

53
Q

describe lipolysis in correlation to gluconeogenesis

A
  • lipases hydrolyze ester linkages (aka lipolysis)

- fatty acids can undergo B-oxidation and can be used to generate energy

54
Q

describe lipolysis in adipose tissue

A

hormone-sensitive lipase (HSL) cleaves a fatty acid from the glycerol backbone)

55
Q

the complete breakdown of a TAG molecule releases what?

A
  • the complete breakdown of a TAG molecule releases 1 glycerol and 3 fatty acids
56
Q

what are the four steps within b-oxidation

A
  1. dehydrogenation
  2. hydration
  3. oxidation
  4. thiolysis
57
Q

each round of b-oxygen removes how many carbons? and produces how many NADH, FADH

A

each round of beta oxidation removes 2 carbons, and produced 1 NADH and 1 FADH2

58
Q

does limiting dietary cholesterol change blood cholesterol levels?

A

for healthy people, limiting dietary cholesterol does not change blood cholesterol much, but for people with high blood cholesterol, a decrease in dietary cholesterol with decrease LDL

59
Q

what are trans fats

A

unsaturated fatty acids with at least one double blond in the trans configuration (both industrial and natural)

60
Q

what does high intake of industrial trans fatty acids result in?

A
  • increased LDL (cholesterol)
  • increased total cholesterol
  • increased inflammation
  • decreased HDL
  • linked to CVD

NUTR 3210 (6 decks)

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