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Physiology Exam 3 > Lecture 7: Digestion and Absorption of Vitamins and Minerals > Flashcards

Lecture 7: Digestion and Absorption of Vitamins and Minerals Flashcards

1
Q

What forms do dietary lipids come in?

A

Triglycerides, cholesterol, phospholipids

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2
Q

How are lipids provided in the diet for domestic animals?

A

Oils of vegetable or marine origin, animal fats

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3
Q

What animal fat is tallow

A

Beef

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4
Q

What animal fat is lard

A

Pork

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5
Q

What fat is grease

A

From restaurants

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6
Q

What is the structure of triglycerides

A

Glycerol + 3 fatty acids

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7
Q

Lipids must be ______ in the SI for digestion and absorption

A

Solubilized

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8
Q

What part of the GIT initiates enzymatic digestion of lipids?

A

Stomach

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9
Q

What is the purpose of churning lipids in the stomach?

A

Breaks lipids into small droplets and increases SA

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10
Q

What hydrolyzes ~10% of ingested TAG?

A

Gastric lipase

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11
Q

What does TAG turn into when hydrolyzed by gastric lipase?

A

Glycerol and FFAs

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12
Q

Stomach __________ chyme into SI

A

slowly empties

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13
Q

Why does the stomach slowly empty chyme into the SI?

A

In order to allow time for pancreatic lipase to digest

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14
Q

What emulsifies lipids in the SI?

A

Bile salts

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15
Q

What is the purpose of bile salts emulsifying lipids?

A

Surround small lipid droplets to increase SA

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16
Q

__________ enzymes digest different lipids

A

Pancreatic

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17
Q

What are examples of pancreatic enzymes that digest different lipids?

A

Lipase, colipase, cholerstol ester hydrolase, phospholipase A2

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18
Q

______ binds to lipase and allows it to digest at lipid-water interface

A

Colipase

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19
Q

What hydrolyzes cholesterol ester

A

Cholesterol ester hydrolase

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20
Q

What happens to cholesterol ester when hydrolyzed by cholesterol ester hydrolase?

A

Free cholesterol + FA + releases glycerol from triglycerides

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21
Q

What is phospholipase A2 activated by?

A

Trypsin

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22
Q

What hydrolyzes phospholipids?

A

Phospholipase A2

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23
Q

What is the result when phospholipids hydrolyzed by phospholipase A2?

A

Iysolecithin + FA

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24
Q

Final hydrolyzed products must now be solubilized in _____ for absorption

A

Micelles

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25
Q

Bile salts solubilize products within SI lumen as _____ (except)

A

Micelles; except glycerol

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26
Q

Micelles diffuse to brush-border membrane of ______

A

Enterocyte

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27
Q

When micelles diffuse to brush-border membrane of enterocyte, products ______________ into cell

A

Release and diffuse

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28
Q

T/F: Bile salts do not diffuse in enterocyte

A

True

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29
Q

Products released and diffused into the enterocyte are then _______

A

Re-esterified to form original compounds

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30
Q

Re-esterified lipids are packaged with _______ to form _______

A

Apoproteins; chylomicrons

31
Q

What is on the inside of chylomicrons

A

Cholesterol and triglycerides in core

32
Q

What is on the outside of chylomicrons

A

Phospholipids and apoproteins

33
Q

Why are apoproteins and important part of chylomicrons?

A

Needed for absorption

34
Q

Chylomicrons package in secretory vesicles and exocytosed across basolateral membrane into ____________

A

Lymphatic capillaries (enter blood of thoracic duct)

35
Q

Why can’t chylomicrons go into vascular capillaries?

A

Too big

36
Q

Steatorrhea

A

Too much fat in poop

37
Q

A problem at any step of digestion or absorption of lipids can result in

A

Steatorrhea

38
Q

Pancreatic insufficiency (chronic pancreatitis) cause

A

Inadequate pancreatic enzymes; so TGs not digested

39
Q

Acidity of duodenal contents can occur if

A

Chyme not neutralized in SI, pancreatic enzymes inactivated

40
Q

Deficiency of bile salts causes…

A

No micelle formation since so bile salts

41
Q

If an ileal resection occurs, what happens to bile salt recycling?

A

Does not occur

42
Q

What happens with bacterial overgrowth?

A

Bacteria removes glycine and taurine from bile salts

43
Q

What causes happens if decreased intestinal cells for absorption?

A

Less SA for absorption of lipid products

44
Q

What causes failure to synthesize apoproteins?

A

Lack of Apo B causes abetalipoproteinemia (chylomicrons can’t form)

45
Q

Vitamins are required as

A

Co-enzymes or co-factors for metabolic reactions

46
Q

How are fat-soluble vitamins absorbed?

A

Within SI lumen, incorporated into micelles for absorption (incorporated into chylomicrons for transport)

47
Q

How are most most water-soluble vitamins absorbed

A

Via Na+/dependent co-transporter in SI

48
Q

What is the one water-soluble vitamin exception?

A

Vitamin B12 requires intrinsic factor for absorption

49
Q

B12 is released from food by

A

Pepsin

50
Q

B12 binds to ______ from salivary secretions

A

R Proteins

51
Q

What in the SI degrade R proteins and release B12?

A

Proteases

52
Q

B12 when released binds with

A

Intrinsic factor

53
Q

Intrinsic factor is synthesized in

A

The stomach

54
Q

______ complex resists proteases, travels to ileum for absorption

A

B12/IF

55
Q

What do you need to absorb calcium in the SI

A

Vitamin D

56
Q

Calcium is absorbed by passive or active transport mechanisms?

A

Both

57
Q

On a low Ca diet, what transport mechanism is used for absorption

A

Active transport

58
Q

What is required to transport Calcium to basolateral membrane

A

Calbindin

59
Q

On high Ca diet, which transport method is used

A

Passive transport

60
Q

What passive diffusion is used on high Ca diet

A

Paracellular

61
Q

How is vitamin D activated?

A

Dietary Vitamin D3 (cholecalciferol) > 25-hydroxycholecalciferol in liver > 1,25 dohydroxycholecalciferol in kidney

62
Q

Active vitamin D promotes synthesis of

A

Calbindin D-28 K

63
Q

Lack of active Vitamin D or calcium results in

A

Rickets and osteomalacia

64
Q

Rickets occurs in what age animals

A

Young

65
Q

Osteomalacia occurs in what age animals

A

Adult

66
Q

What are the two forms of iron

A

Free iron (Fe2+) or heme iron

67
Q

What transporter is used for iron absorption?

A

DMT-1

68
Q

Heme iron is digested into free iron by _______ enzymes inside enterocytes

A

Lysosomal

69
Q

Free iron binds to _______ inside enterocytes for transport into blood via ferroportin

A

apoferritin

70
Q

Once free iron binds to apoferritin it gets transported into blood via

A

ferroportin

71
Q

What does free iron bind to in plasma

A

transferrin

72
Q

Iron circulates bound to

A

transferrin

73
Q

Iron is stored as

A

ferritin

Physiology Exam 3 (13 decks)

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