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Fundamentals of Nutrition > Lipid digestion & Metabolism > Flashcards

Lipid digestion & Metabolism Flashcards

1
Q

What is esterification?

A

fatty acids joined with glycerol to form an ester.

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2
Q

What types of fatty acids are they? what makes them distinct?

A
  1. Saturated –> have NO double bonds
  2. Monounsaturated–> have 1 double bond
  3. Polyunsaturated–> have 2 or more double bonds
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3
Q

give an example of saturated, monounsaturated and polyunsaturated fatty acids.

A
  1. Stearic acid = saturated fatty a
  2. oleic acid = monosaturated
  3. Linoleic acid =polyunsaturated
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4
Q

what types of polyunsaturated fatty acids are there?

A

Cis (same side + folding of the molecule into a U shape) or Trans (opposite sides + linear shape)

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5
Q

What are the classes of lipids?

A
  • sterols & steroids
  • phospholipids
  • glycolipids
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6
Q

What are sterols made of? give an example of one.

A

sterols are monohydroxy alcohol of steroidal structures ex: cholesterol

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7
Q

what are sterols & steroids precursors for?

A
  • bile acids
  • sex hormones
  • cholecaliferol
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8
Q

what are the qualities of cholesteryl esters?

A

they have a lower solubility in water than cholesterol and are more hydrophobic

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9
Q

What is the main lipid constituent of the cell membrane?

A

Phospholipids

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10
Q

what are two types of phospholipids?

A
  1. glycerophosphatides
  2. sphingophosphatides
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11
Q

what do glycerophosphatides contain?

A

glycerophosphatides contain phosphoric acid and they form derivatives with other compounds in the form of phosphatidyl alcohols (ex: lecithin)

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12
Q

what is the most common sphingolipid?

A

sphingomyelins

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13
Q

How are sphingomyelins important in the nervous system?

A

they form the myelin sheath which protects neurons

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14
Q

what do glycolipids contain?

A

they contain carbohydrate component & spingosine moiety

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15
Q

what are the main glycolipids?

A

cerebrosides & gangliosides

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16
Q

what is the function of glycolipids? where are they found?

A

the main function of glycolipids is structural.

  • Cerebrosides: found in white matter of brain
  • Gangliosides: provide the carbohydrate determinants of the human blood group
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17
Q

what are the biological roles for lipids?

A
  • source of energy
  • structural components of membranes (both cellular and subcellular)
  • lubricants for body surfaces (sebaceous glands)
  • signaling molecules (extra and intra cellular)
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18
Q

digestion of lipids starts in the ________ by the action of _________.

A

MOUTH by the action of Lingual lipase

**STOMACH **by the action of Gastric lipase

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19
Q

which one is gastric lipase more effective at hydrolyzing triglycerides? medium chain fatty acids or long chain fatty acids?

A

Medium chain fatty acids

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20
Q

Do gastric lipase hydrolyze cholesteryl esters or phospholipids?

A

NO

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21
Q

Gastric motility is ______ by the presence of fat.

A

gastric motility is INHIBITED by the presence of fat (high satiety value).

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22
Q

what does the pancreas secrete to neutralize chyme entering the small intestine?

A

Bicarbonates (HCO3)

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23
Q

where does emulsification with bile salts occur?

A

Small intestine

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24
Q

most of triglyceride digestion is done by _________ in the _________

A

Pancreatic lipase in the duodenum

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25
what is the end products of triglyceride break down by pancreatic lipase?
Monoglycerides and free fatty acids
26
Pancreatic lipase is ____ effective with a bile salt-lipid mixture
MORE
27
what is required for the activation of pancreatic lipase?
a cofactor called colipase
28
what enzyme is found in the mouth that digests lipids? what lipids does it digest? what are the end products?
Lingual lipase digests **triacylglycerols into di-acylglycerol and fatty acids**
29
what is the end product of digestion of phospholipids?
free fatty acids & lysophosphatidylcholine
30
what enzyme(s) digest phospholipids?
Phospholipase A2 and phospholipase B
31
what enzyme hydrolyzes cholesterol ester? what is it hydrolyzed to ?
cholesterol esterase. Hydrolyzed to free cholesterol and fatty acids (in the small intestine)
32
what are the end products of lipid digestion?
- free fatty acids -monoacylglycerol - lysophosphatidylcholine -cholesterol
33
what is the main purpose of bile salt micelles?
to make lipids more soluble in water phase overlying enterocytes (more lipid molecules can be delivered to the brush border membrane by bile salt micelles)
34
how do monoglycerides and fatty acids enter the enterocyte?
by diffusion
35
what are the two mechanisms for uptake of lipid digestion products?
1. Passive diffusion 2. Carrier-mediated transport (Ex: FATP4)
36
when are carrier mediated transport needed to uptake lipids?
when fatty acid concentrations are low
37
water soluble digested lipids (ex: glycerol) are effectively taken up by what method?
diffusion
38
how does degree of unsaturation affect absorption of lipids?
As unsaturation increases, absorption efficiency increases.
39
where in the enterocytes is triacylglycerol resynthesized?
in the endoplasmic reticulum
40
triacylglycerols are packaged into _____ in the \_\_\_\_\_\_\_.
triacylglycerols are packaged into lipoproteins in the golgi.
41
where does re-esterification of digested lipids occur?
at the cytosolic surface of the ER inside the intestinal mucosal cells
42
what are the two pathways for re-esterification of digested lipids?
1. monoacylglycerol pathway (normal conditions most use this pathway) 2. glycerol-3-phosphate pathway
43
Chylomicrons are a type of \_\_\_\_\_\_?
Lipoprotein
44
What are apoproteins?
Triacylglycerol lipid droplets and cholesteryl esters surrounded by the polar phospholipids and proteins
45
what are the three types of lipoproteins in the small intestine?
1. chylomicrons 2. VLDL 3. HDL
46
which lipoproteins are secreted after a fat rich meal?
Chylomicrons
47
which lipoproteins are secreted during fasting?
VLDL
48
what are some major apoproteins associated with chylomicrons?
- A-I -Apo A-IV -Apo B-48
49
what is needed for the addition of triglyceride to chylomicron?
it requires microsomal triglycerol transfer protein (MTP)
50
where does the final step of chylomicron formation occur? (addition of CHO)
in the golgi
51
why are lipids re-esterified?
to maintain low intercellular concentrations of digested lipids
52
what is the function of Apoproteins?
signaling & attracts digestive enzyme
53
what enzyme is involved in esterification of cholesterol ?
acyl CoA cholesterol acyltransferase
54
where do chylomicrons move to after leaving the intestinal cells?
into the lymphatic capillaries (vessels) by exocytosis and then enter the venous plasma via the left thoracic lymph duct
55
what enzyme is involved in the hydrolysis of triglycerides from chylomicrons? where does this occur?
lipoprotein lipases in the muscles & adipose tissues
56
in the liver (hepatocytes) triglycerides are assembled in the form of \_\_\_\_\_\_\_.
VLDL
57
LPL (lipoprotein lipase) in cardiac muscles has ______ affinity than that in adipose tissue.
Higher
58
during fasting what concentrations are there of VLDL and chylomicrons?
during fasting, chylomicrons are almost absent, and VLDL concentration (hepatic) is low
59
during fasting, lipoprotein lipase concentration in the ______ tissue is down regulated while that of _______ is maintained.
adipose= down regulated cardiac muscles = maintained
60
what is used by the muscles for energy during fasting?
triglycerides (VLDL)
61
After a meal, (fed state) where are triglycerides (as chylomicrons) stored?
they are stored in the adipose tissue

Fundamentals of Nutrition (14 decks)

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