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IHN: Biochemistry 2 > Quiz 4: Zinc > Flashcards

Quiz 4: Zinc Flashcards

(85 cards)

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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
primary method of zinc absorption (with usual intake)
saturable carrier mediated ZIP4
26
major transporter of zinc across enterocyte's brush border membrane
ZIP4
27
ZIP4 aka
Zrt and Irt like protein 4
28
ZIP4 is expressed throughout
GI tract
29
with high Zinc intakes, ZIP4 is degraded __ rapidly to __ absorption
with high Zinc intakes, ZIP4 is degraded **more** rapidly to **downregulate** absorption
30
zinc restriction enhances ZIP4 __ which rapidly __ ZIP4 synthesis and shifts ZIP4 proteins to __
zinc restriction enhances ZIP4 **mRNA stability** which rapidly **induces** ZIP4 synthesis and shifts ZIP4 proteins to **brush border membrane**
31
enhanced ZIP4 synthesis is mediated by upregulation of __ which binds __ region on ZIP4 gene
enhanced ZIP4 synthesis is mediated by upregulation of **transcription factor KLF4** which binds **promoter** region on ZIP4 gene
32
digestion, absorption, transport of zinc steps
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
33
mutation in ZIP4 causes
acrodermatitis enteropathica
34
acrodermatitis enteropathica
poor zinc absorption skin lesions impaired growth low plasma zinc can be fatal
35
how to treat acrodermatitis enteropathica
high doses of zinc (forces paracellular diffusion)
36
what amino acid can bind zinc to allow it to enter enterocyte
histidine
37
what other ZIP is found on brush border and when is it upregulated
upregulated with zinc restriction ZIP11
38
__% of zinc is absorbed from the typical US diet
**20-50**% of zinc is absorbed from the typical US diet
39
fractional zinc absorption varies from __ higher intakes = absorption __
fractional zinc absorption varies from **10-80%** higher intakes = absorption **diminishes**
40
enhancers of zinc absorption
1. glutathione 2. organic acids (citric acid, picolinic acid) 3. amino acids 4. low pH GOAL
41
inhibitors of zinc absorption
1. high pH 2. phytic acid 3. oxalic acid 4. polyphenols 5. selected nutrients HiPOPS
42
__ and products of protein digestion (__ and __) enhance zinc absorption
**glutathione** and products of protein digestion (**tripeptides** and **amino acids**) enhance zinc absorption
43
zinc binds to sulfur (__ alone, or part of __) and nitrogen (__)
zinc binds to sulfur (**cysteine** alone, or part of **glutathione**) and nitrogen (**histidine**)
44
antacids __ gastric and proximal instestinal pH and __ zinc absorption
antacids **increase** gastric and proximal instestinal pH and **decrease** zinc absorption
45
inhibitors of zinc sources: phytic acid: oxalic acid polyphenols: other minerals:
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
zinc supplement should not be consumed at same time as a __ supplement on a __ stomach
zinc supplement should not be consumed at same time as a **nonheme** supplement on a **empty** stomach
47
zinc supplements should also not be taken with
other minerals
48
3 options for zinc use within enterocyte
1. functinal use in enterocyte 2. stored in enterocyte 3. transported through cytosol to enter blood and be used by other tissues
49
most zinc that isn't used is __ or bound to __
most zinc that isn't used is **sequestered** or bound to **proteins**
50
do we have free zinc
very little
51
ZnT7 functions
inside cell moves zinc into trans-Golgi network
52
ZIP7 function
transport out of trans-Golgi network
53
metallothionein function
zinc's main short-term storage protein IC binding ligand
54
metallothionein has a strangely high amount of __ which helps with __ binding
metallothionein has a strangely high amount of **cysteine** which helps with **metal** binding
55
2 main functions of metallothionein
1. transport zinc to zinc-requiring enzymes 2. store zinc transiently
56
how does zinc exit enterocyte and enter blood
ZnT1 transports zinc out of duodenal and jejunal cells (in exchange for H+ or K+)
57
what does ZnT1 require
nothing
58
ZnT1 expression
increased with high zinc intake not affected by low
59
in addition to ZnT1, __ on basolateral membrane sends zinc into blood
in addition to ZnT1, **DMT1** on basolateral membrane sends zinc into blood
60
zinc form in portal blood
loosely bound to albumin
61
after blood zinc is taken up by
liver
62
which ZIP transports zinc into hepatocytes and is increased during infections and trauma
ZIP14
63
which ZIP is expressed in intestine, pancreas, liver, kidney mucosal zinc transport (blood to intestine)
ZIP5
64
where is zinc found in body
ALL tissues/organs mostly liver, kidneys, muscle, skin, and bones
65
within cells __% of zinc bound to proteins in nucleus __% in cytosol rest in __
within cells **30-40**% of zinc bound to proteins in nucleus **50**% in cytosol rest in **cell membranes**
66
zinc is stored attached to
metallothionein
67
metallothionein other functions
1. antioxidant
68
a metal trxn factor reliant on zinc binds __ to induce thionein synthesis
a metal trxn factor reliant on zinc binds **MRE** to induce thionein synthesis
69
zinc roles
1. facilitates biochemical rxns 2. metabolic pathways 3. gene expression (trxn factors)
70
zinc dependent enzymes
metalloenzymes
71
rxns zinc has a role in
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
zinc role in gene expression
zinc fingers
73
other roles of zinc
1. cell membranes 2. insulin (carb metabolism) 3. basal metabolic rate 4. immune function
74
pharmacological uses of zinc
colds eye health
75
zinc and vitA
zinc deficieny prevents vitA mobilization
76
excess zinc impacts __ absorption
excess zinc impacts **copper, calcium** absorption
77
__ in high conc competes for zinc binding sites
**cadmium** in high conc competes for zinc binding sites
78
zinc excretion methods
GI tract: feces kidneys skin: semen and menses
79
which ZIP and ZnT facilitate excretion in feces
ZIP5 and ZnT6
80
zinc deficiency in children symptoms
growth retardation skeletal abnormalities poor wound healing diarrhea rash
81
zinc deficiency in adults symptoms
anorexia diarrhea lethargy depression vision problems wound healing
82
populations at risk for deficiency
older adults vegetarians alcoholics low SES thiazide diuretics (increase zinc excretion)
83
zinc toxicity
metallic taste headache, nausea, vomiting, cramps, bloody diarrhea
84
chornic low zinc can cause __ deficiency
chornic low zinc can cause **copper** deficiency
85
assessing zinc status
fasting serum or plasma

IHN: Biochemistry 2 (38 decks)

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