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Micronutrients > Zinc > Flashcards

Flashcards in Zinc Deck (34)
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1

ZnTs

Moves zinc out of cells.

2

*** ZIP14 ***
Out of blood into liver

Located on hepatocytes, upregulated during infection.

Removes zinc from blood and away from infective organisms that can use it.

Defense mechanism.
Up regulation can indicate infection.

Liver.

3

ZIP4

Inversely related to zinc status.

Zinc absorption low = more ZIP4 (enhances absorption)

Mutation causes malabsorption syndrome.

4

ZIP5
Transfer to enterocyte

Can reabsorb zinc back into enterocyte.

Reabsorbs zinc if there's too much in circulation.

Sloughs off cells to get rid of zinc.

Enterocyte.

5

*** ZnT6 ***
Transfer to lumen

Recycles zinc from enterocyte to the lumen to be excreted. Active.

Lumen.

Purposeful elimination.

6

*** ZnT1 ***
Out of cells into blood

Transports zinc out of cells.

Tissue cells.

7

ZIPs

Moves zinc into cells.

8

Sources

Red meats, oysters, fortified cereals.

20-30% bioavailability.

Supplementation on empty stomach.

9

RDA

11mg men
8 mg women

Double for vegetarians (decreased bioavailability in plant foods due to non heme iron)
Higher absorption probably (low zinc status)

10

Assessment

Serum

11

Function

Component of ~200 metalloenzymes.

Structural integrity more so than functional.
Binds to AA at catalytic sites.

12

Zinc fingers

Solid, stable structure for proteins. Many functions.

Can curl along DNA strands to read DNA sequences.

13

*** Metalloenzyme component: Ligase and Lyase ***

Catalyzes the joining of 2 large molecules.
Bond forming.

Catalyzes the breaking of various bonds.

14

Zinc in development/ growth

Regulates gene expression and cell replication.

Can result in poor growth in children if deficient because cells don't grow fast enough.

Retardation and skeletal growth impaired.

15

Zinc and infections

Structural role in hormones (thymulin - immunity)

Retionol to retinal conversion (RBP synthesis retinonol binding protein)

16

Zinc and taste

Taste acuity.

Zinc required for gustin synthesis.

Gustin is zinc-containing protein in saliva.

17

Deficiency symptoms

Growth retardation, skeletal abnormalities, and delayed sexual maturation in children. Zn used in cell division and DNA replication.

Infection (thymulin and retinal conversion)
Skin lesions (cell growth)
Loss of taste (hypogeusia) [gustin]

18

Toxicity

UL 40mg/ day

Also creates copper deficiency (zinc binds to metallothionine better than copper)

19

Protein carriers that transfer zinc through blood

60% albumin

Transferrin, immunoglobulin, and the AA's cysteine and histidine.

20

Zinc storage

Metallothionine stores zinc in tissues.

Liver stores zinc when it's not being transferred.

Albumin contains 60% of Zn in blood

21

Enhancers

Acids: low pH, HCl, citric acid, AA.

Zinc is usually bound to proteins, which acids break away.

22

Inhibitors

Non heme iron, calcium, antacids, tannins, phytates, oxalate.

Excrete zinc instead of absorb.

23

Thionein

Upregulated when zinc levels are high.

Binds to zinc to form metallothionine.

24

Gustin

Zinc dependent protein used for taste

25

Transport

Transferred through the blood bound to protein carriers:
Albumin, Transferrin, Immunoglobulins, etc.
AA: histidine and cysteine

26

ZIP1
Transport to tissue cells

Brings zinc out of blood into cell.

Can either be stored, used as a cofactor, or ego to nucleus to upregulate thionine to bind to something.

27

Metallothionine

Directly correlated to Zn status. Bind to Zn.

More Zn = more metallothionine

28

How can zinc be recycled?

Enterohepatic circulation

29

Supplement

Should be taken on empty stomach.

30

Excretion

GI tract in feces
Zn bound to metallothionine lost in cell sloughing

ZIP5 and ZnT6 purposeful elimination (GI)