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Biochemistry-Block 2 CC > Lipid Digestion > Flashcards

Lipid Digestion Flashcards

1
Q

Adults typically consume

A

~81 grams of lipids per day

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2
Q

90% of the lipids consumed are

A

TAG (72 g)

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3
Q

The other 10% of lipids consumed are

A

cholesterols, cholesterol esters, phospholipids, free fatty acids

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4
Q

______ are acid-stable lipases that function in the stomach at optimal pH between pH 4 to pH 6

A

Acid lipases

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5
Q

What are the two types of Acid-Lipases?

A

Lingual Lipase and Gastric Lipase

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6
Q

____ are secreted from the glands at the back of the tongue.

A

Lingual Lipase

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7
Q

_____ are secreted from the gastric mucosa

A

Gastric Lipase

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8
Q

Acid Lipases target TAG containing _________ Fatty Acids. Give an example.

A

Short and Medium Chain Fatty Acids

Milk Fat

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9
Q

When are acid lipases especially important?

A

Neonates when milk is the primary food source

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10
Q

Name the two complementary actions of the emulsification of dietary lipids.

A

Mechanical Agitation and Bile Salt Secretion

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11
Q

_______ of dietary material via peristalsis increases the lipid droplet surface area

A

Mechanical Agitation

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12
Q

_______

  • made in the liver
  • stored in the gall bladder
  • secreted to the small intestine
  • have detergent properties that stabilize particles as they become smaller, preventing them from coalescing.
A

Bile Salts

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13
Q

Enzymes secreted from the pancreas digest dietary ____, ______ and _____

A

TAG, cholesteryl esters, phospholipids

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14
Q

_____ is the removal of specific fatty acids by breaking ester bonds attaching the fatty acids

A

Digestion

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15
Q

Name the pancreatic enzymes important for TAG digestion

A

Pancreatic Lipase and Colipase

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16
Q

This pancreatic enzyme is extremely active (high catalytic efficiency), and represents 2 to 3% of total protein in pancreatic secretions.

A

Pancreatic Lipase

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17
Q

____ is an esterase, cleaves FA at carbon-1 and -3 of the glycerol backbone producing 2 free fatty acids (thus producing a 2-monoacylglycerol)

A

Pancreatic Lipase

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18
Q

Colipase is also secreted from the pancreas and binds pancreatic lipase at a _____ ratio.

A

1:1

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19
Q

The function of ___ is to anchor pancreatic lipase at the lipid-aqeuous interface to promote pancreatic lipase enzymatic activity when inhibitory bile salts are present

A

Colipase

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20
Q

Dietary Cholesterol is present in two forms:
85-90% ______ cholesterol (free)
10-15% ______ cholesterol (cholesteryl ester)

A

unesterified, esterified

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21
Q

_______ is a pancreatic enzyme secreted to the small intestine, it digests esterified cholesterol (cholesteryl esters)

A

Cholesterol esterase

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22
Q

Cholesterol esterase produces _____ and _____

A

cholesterol and free fatty acids

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23
Q

Cholesterol esterase makes all of the cholesterol produced ______

A

nonesterified

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24
Q

Bile salts promote _____ activity

A

cholesterol esterase

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25
Q

Ingested phospholipids are digested by sequential removal of fatty acids by two different pancreatic enzymes, _______ and _______.

A

Phospholipase A2 and Lysophospholipase

26
Q

_____ removes the fatty acid from position 2 to produce lysophospholipid and a free fatty acid

A

Phospholipase A2

27
Q

_______ removes the fatty acid from position 1 to generate 1 fatty acid and 1 glycerylphosphoryl base

A

Lysophospholipase

28
Q

Glycerylphosphoryl bases can be:

A

absorbed, further digested or excreted in the feces

29
Q

What does the digestion of phospholipids produce?

A

2 fatty acids and 1 glycerylphosphoryl base

30
Q

_________ in the mucosa of the lower duodenum and jejunum sense:

  • lipids and partially digested proteins
  • low pH of chime entering the intestine
A

Gut Endocrine Cells

31
Q

What do Gut Endocrine Cells secrete into the blood?

A

-2 small peptide hormones: CCK and secretin

32
Q

________ is a small peptide hormone secreted to the blood in response to the presence of lipid and partially digested proteins

A

cholecystokinin (CCK)

33
Q

_______:

  • promotes pancreatic enzyme secretion
  • causes gall bladder to release bile
    - bile salts
    - phospholipids
    - free cholesterol
A

CCK

34
Q

_______;

decrease gastric motility, reducing release rate of gastric contents to the small intestine

A

CCK

35
Q

_____: small peptide hormone secreted to the blood in response to the low pH of chime entering the intestine

A

Secretin

36
Q

______ promotes the release of bicarbonate rich solution from the pancreas to the small intesting, providing the appropriate pH for optimal pancreatic enzyme function

A

Secretin

37
Q

Lipid digestion in the jejunum generates 3 primary products:

A
  • free fatty acids
  • free cholesterol (very marginal)
  • 2-monoacylglycerol
38
Q

______:

  • disk shaped clusters of amphipathic lipids
  • formed from these three products (cholesterol, fatty acids, 2-monoacylglycerol) and fat-soluble vitamins (A,D,E,K)
A

Micelles

39
Q

________: Intestinal Mucosal Cells

A

Enterocytes

40
Q

Mixed Micelles are soluble in the intestinal lumen, and can associated with the brush border membrane of enterocytes where they are ______

A

absorbed

41
Q

_______, relative to other dietary lipids are poorly absorbed by enterocytes

A

Cholesterol

42
Q

____ and _______ can be absorbed directly by enterocytes without mixed micelles

A

short and medium chain fatty acids

43
Q

The absorbed mixture of lipids is processed at the ______, the site for complex lipid biosynthesis

A

endoplasmic reticulum

44
Q

__________: converts LCFA to their activated form by using energy from ATP-> AMP to form fatty acyl-CoA

A

Fatty acyl-CoA synthetase/Thiokinase

45
Q

______: 2-monoacylglycerol is converted to TAG by an enzyme complex that sequentially adds activated fatty acids (above) by two enzymatic acyltransferase activities

A

TAG synthase

46
Q

______ esterifies cholesterol with a fatty acid

A

acyl CoA: cholesterol acyltransferase

47
Q

_____ are reacylated by a family of specific acyltransferases to form phospholipids

A

Lysophospholipids

48
Q

______ and ______ are not activated, but are released into the portal circulation, and likely carried by serum albumin to the liver

A

short and medium chain fatty acids

49
Q

TAG and cholesteryl esters are hydrophobic and thus need to be packaged into stable lipid droplets, called ________, to be secreted by intestinal enterocytes

A

chylomicrons

50
Q

in ________, TAG and cholesteryl esters are surrounded by a spherical single layer of phospholipids, cholesterol and apoliprotein B-48

A

chylomicrons

51
Q

______: lymph that contains chylomicrons

A

chyle

52
Q

Describe the route that chyle takes.

A

Enterocytes–>Lymph–>Blood–>Cells

53
Q

_________ are:

  • produced at the ER of the enterocytes
  • exocytosed into the lacteals (lymphatic vessels that origniate at the villi of the small intestine)
A

Chylomicrons

54
Q

________:

  • enzymatically degrades TAG in the circulating chylomicrons to free fatty acids and glycerol
  • is synthesized and secreted primarily by muscle and adipose tissues (heart, lung, kidney, liver)
  • associates with the lumen endothelial cells of capillary beds
A

Lipoprotein lipase

55
Q

The free fatty acids are generally taken up immediately by the ______ and ______.

A

Adjacent Muscle and Adipose Tissue

56
Q

If the free fatty acids are not taken up by the adjacent muscle and adipose tissue, they will circulate in association with _____ until taken up

A

serum albumin

57
Q

Glycerol is taken up by the ____ and used to produce glycerol 3-phosphate which can enter glycolysis or GNG

A

liver

58
Q

Most of the materials are hydrolyzed to their component parts, but _____ and _____ are recycled.

A

nitrogenous bases and phospholipids

59
Q

_____ is an autosomal recessive disease with varying degrees of severity and multiple alleles.

A

cystic fibrosis

60
Q

Cystic Fibrosis is termed pancreatic infufficiency, which results in ____ and _____

A

significant reduction in dietary calories and decreased fat-soluble vitamin up-take

61
Q

What is the treatment for CF?

A

-enzyme replacement and fat-soluble vitamin supplements

62
Q

Most fatty acids in the diet are ______

A

esterified

Biochemistry-Block 2 CC (13 decks)

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