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IHN: Biochemistry 2 > Quiz 4: Zinc > Flashcards

Quiz 4: Zinc Flashcards

1
Q

body contains __g of zinc

A

body contains 1.5-3g of zinc

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2
Q

where is zinc found in the body

A

ALL organs, tissues, and body fluids

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3
Q

2 organs with most zinc

A

muscle
bone

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4
Q

zinc is a metal that can exist in several __, but is most found as the __ ion (__)

A

zinc is a metal that can exist in several valence states, but is most found as the divalent ion (Zn2+)

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5
Q

zinc is found in foods complexd with __ and __ that are part of __ and __

A

zinc is found in foods complexd with nucleic acids and amino acids that are part of peptides and proteins

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6
Q

food sources of zinc

A

red meats (organs)
seafood (oysters)
poultry, pork
dairy

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7
Q

__ products provide 40-70% of zinc consumed by most people in the US

A

animal products provide 40-70% of zinc consumed by most people in the US

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8
Q

in US, other 30% of zinc is provided by

A

cereals

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9
Q

zinc from __ has lower absorption

A

zinc from plants has lower absorption

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10
Q

factors that inhibit zinc’s availability

A
  1. heating
  2. maillard reaction products (amino acid-carb complexes) from browning
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11
Q

supplement forms of zinc

A
  1. zinc oxide
  2. zinc sulfate
  3. zinc acetate
  4. zinc chloride
  5. zinc gluconate
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12
Q

how should zinc supplements be consumed?

A

on an empty stomach without simultaneously ingesting other mineral supplements (Fe, Ca)

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13
Q

side effects of zinc supplements

A

abdominal pain
dyspepsia
nausea, vomiting, diarrhea

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14
Q

topical zinc products form

A

zinc oxide
zinc chloride

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15
Q

what is topical zinc used for

A

wound managements

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16
Q

percutaneous absorption of zinc depends on skin’s __ and requires __ on skin’s surface

A

percutaneous absorption of zinc depends on skin’s integrity and requires acidic moisture on skin’s surface

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17
Q

less intact skin = __ zinc absorbed

A

less intact skin = more zinc absorbed

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18
Q

in presence of intact skin barrier, zinc binds to __ groups in epidermal __ upon release from zinc oxide or chloride salt in __ environment

A

in presence of intact skin barrier, zinc binds to sulfhydryl groups in epidermal keratin upon release from zinc oxide or chloride salt in acidic environment

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19
Q

how long does it take to absorb zinc after topical application

A

60 minutes

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20
Q

zinc that doesn’t get into circulation, binds to __ in epidermal ketatinocytes and is eventually __ with skin cell turnover __

A

zinc that doesn’t get into circulation, binds to metallothionein in epidermal ketatinocytes and is eventually sloughed off with skin cell turnover

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21
Q

endogenous zinc from __, __, and __ secretions is released into GI tract with food ingestion and augments zinc present from __ and __

A

endogenous zinc from pancreatic, intestinal, and biliary secretions is released into GI tract with food ingestion and augments zinc present from dietary food sources and supplements

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22
Q

zinc secreted into GI tract can be __, important for zinc homeostasis

A

zinc secreted into GI tract can be reabsorbed, important for zinc homeostasis

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23
Q

zinc absorption location

A

proximal small intestine:
duodenum + upper jejunum

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24
Q

2 mechanisms of of zinc absorption

A
  1. carrier-mediated transport
  2. diffusion
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25
Q

primary method of zinc absorption (with usual intake)

A

saturable
carrier mediated
ZIP4

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26
Q

major transporter of zinc across enterocyte’s brush border membrane

A

ZIP4

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27
Q

ZIP4 aka

A

Zrt and Irt like protein 4

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28
Q

ZIP4 is expressed throughout

A

GI tract

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29
Q

with high Zinc intakes, ZIP4 is degraded __ rapidly to __ absorption

A

with high Zinc intakes, ZIP4 is degraded more rapidly to downregulate absorption

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30
Q

zinc restriction enhances ZIP4 __ which rapidly __ ZIP4 synthesis and shifts ZIP4 proteins to __

A

zinc restriction enhances ZIP4 mRNA stability which rapidly induces ZIP4 synthesis and shifts ZIP4 proteins to brush border membrane

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31
Q

enhanced ZIP4 synthesis is mediated by upregulation of __ which binds __ region on ZIP4 gene

A

enhanced ZIP4 synthesis is mediated by upregulation of transcription factor KLF4 which binds promoter region on ZIP4 gene

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32
Q

digestion, absorption, transport of zinc steps

A
  1. bound zinc released from food
  2. zinc absorbed by ZIP4 in brush border
  3. DMT1 and amino acids play minor role across brush border
  4. zinc bound by inhibitors goes into feces, absorption can be enhanced by organic acids, decreased pH, or chelators
  5. high zinc intake = paracellular absorption
  6. within cells, zinc used or stored in vesicles (in trans-Golgi network) or as part of metallothionein
  7. zinc transported across basolateral by ZnT1
  8. zinc binds proteins for transport in the blood
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33
Q

mutation in ZIP4 causes

A

acrodermatitis enteropathica

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34
Q

acrodermatitis enteropathica

A

poor zinc absorption
skin lesions
impaired growth
low plasma zinc
can be fatal

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35
Q

how to treat acrodermatitis enteropathica

A

high doses of zinc (forces paracellular diffusion)

36
Q

what amino acid can bind zinc to allow it to enter enterocyte

A

histidine

37
Q

what other ZIP is found on brush border and when is it upregulated

A

upregulated with zinc restriction
ZIP11

38
Q

__% of zinc is absorbed from the typical US diet

A

20-50% of zinc is absorbed from the typical US diet

39
Q

fractional zinc absorption varies from __
higher intakes = absorption __

A

fractional zinc absorption varies from 10-80%
higher intakes = absorption diminishes

40
Q

enhancers of zinc absorption

A
  1. glutathione
  2. organic acids (citric acid, picolinic acid)
  3. amino acids
  4. low pH

GOAL

41
Q

inhibitors of zinc absorption

A
  1. high pH
  2. phytic acid
  3. oxalic acid
  4. polyphenols
  5. selected nutrients

HiPOPS

42
Q

__ and products of protein digestion (__ and __) enhance zinc absorption

A

glutathione and products of protein digestion (tripeptides and amino acids) enhance zinc absorption

43
Q

zinc binds to sulfur (__ alone, or part of __) and nitrogen (__)

A

zinc binds to sulfur (cysteine alone, or part of glutathione) and nitrogen (histidine)

44
Q

antacids __ gastric and proximal instestinal pH and __ zinc absorption

A

antacids increase gastric and proximal instestinal pH and decrease zinc absorption

45
Q

inhibitors of zinc sources:
phytic acid:
oxalic acid
polyphenols:
other minerals:

A

inhibitors of zinc sources:
phytic acid: plant foods (legumes, nuts)
oxalic acid: spinach, berries, chocolate, tea
polyphenols: tea, coffee, fibers
other minerals: iron and calcium

46
Q

zinc supplement should not be consumed at same time as a __ supplement on a __ stomach

A

zinc supplement should not be consumed at same time as a nonheme supplement on a empty stomach

47
Q

zinc supplements should also not be taken with

A

other minerals

48
Q

3 options for zinc use within enterocyte

A
  1. functinal use in enterocyte
  2. stored in enterocyte
  3. transported through cytosol to enter blood and be used by other tissues
49
Q

most zinc that isn’t used is __ or bound to __

A

most zinc that isn’t used is sequestered or bound to proteins

50
Q

do we have free zinc

A

very little

51
Q

ZnT7 functions

A

inside cell
moves zinc into trans-Golgi network

52
Q

ZIP7 function

A

transport out of trans-Golgi network

53
Q

metallothionein function

A

zinc’s main short-term storage protein
IC binding ligand

54
Q

metallothionein has a strangely high amount of __ which helps with __ binding

A

metallothionein has a strangely high amount of cysteine which helps with metal binding

55
Q

2 main functions of metallothionein

A
  1. transport zinc to zinc-requiring enzymes
  2. store zinc transiently
56
Q

how does zinc exit enterocyte and enter blood

A

ZnT1 transports zinc out of duodenal and jejunal cells (in exchange for H+ or K+)

57
Q

what does ZnT1 require

A

nothing

58
Q

ZnT1 expression

A

increased with high zinc intake
not affected by low

59
Q

in addition to ZnT1, __ on basolateral membrane sends zinc into blood

A

in addition to ZnT1, DMT1 on basolateral membrane sends zinc into blood

60
Q

zinc form in portal blood

A

loosely bound to albumin

61
Q

after blood zinc is taken up by

A

liver

62
Q

which ZIP transports zinc into hepatocytes and is increased during infections and trauma

A

ZIP14

63
Q

which ZIP is expressed in intestine, pancreas, liver, kidney
mucosal zinc transport (blood to intestine)

A

ZIP5

64
Q

where is zinc found in body

A

ALL tissues/organs
mostly liver, kidneys, muscle, skin, and bones

65
Q

within cells
__% of zinc bound to proteins in nucleus
__% in cytosol
rest in __

A

within cells
30-40% of zinc bound to proteins in nucleus
50% in cytosol
rest in cell membranes

66
Q

zinc is stored attached to

A

metallothionein

67
Q

metallothionein other functions

A
  1. antioxidant
68
Q

a metal trxn factor reliant on zinc binds __ to induce thionein synthesis

A

a metal trxn factor reliant on zinc binds MRE to induce thionein synthesis

69
Q

zinc roles

A
  1. facilitates biochemical rxns
  2. metabolic pathways
  3. gene expression (trxn factors)
70
Q

zinc dependent enzymes

A

metalloenzymes

71
Q

rxns zinc has a role in

A
  1. acid-base balance
  2. phosphate release
  3. aldehyde synthesis
  4. protein digestion
  5. heme synthesis
  6. antioxidant
  7. phospholipid metabolism
  8. folate digestion
  9. wound repair
  10. nucleic acid synthesis and cell replication and growth
72
Q

zinc role in gene expression

A

zinc fingers

73
Q

other roles of zinc

A
  1. cell membranes
  2. insulin (carb metabolism)
  3. basal metabolic rate
  4. immune function
74
Q

pharmacological uses of zinc

A

colds
eye health

75
Q

zinc and vitA

A

zinc deficieny prevents vitA mobilization

76
Q

excess zinc impacts __ absorption

A

excess zinc impacts copper, calcium absorption

77
Q

__ in high conc competes for zinc binding sites

A

cadmium in high conc competes for zinc binding sites

78
Q

zinc excretion methods

A

GI tract: feces
kidneys
skin: semen and menses

79
Q

which ZIP and ZnT facilitate excretion in feces

A

ZIP5 and ZnT6

80
Q

zinc deficiency in children symptoms

A

growth retardation
skeletal abnormalities
poor wound healing
diarrhea
rash

81
Q

zinc deficiency in adults symptoms

A

anorexia
diarrhea
lethargy
depression
vision problems
wound healing

82
Q

populations at risk for deficiency

A

older adults
vegetarians
alcoholics
low SES
thiazide diuretics (increase zinc excretion)

83
Q

zinc toxicity

A

metallic taste
headache, nausea, vomiting, cramps, bloody diarrhea

84
Q

chornic low zinc can cause __ deficiency

A

chornic low zinc can cause copper deficiency

85
Q

assessing zinc status

A

fasting serum or plasma

IHN: Biochemistry 2 (38 decks)

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