Micronutrients I - Minerals Flashcards Preview

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Flashcards in Micronutrients I - Minerals Deck (77):
0

Zinc deficiency

tissue damage - oxidative stress, apoptosis
immune deficiencies
late onset secondary sex chara.
growth reduction/ developmental changes
poor appetite - pts lose sense of taste
malabsorption disorders - inflammatory bowel disease

1

Zinc excess

gastric distress, dizziness, nausea
Emetic effect at doses as low as 50 mg
Can reduce Cu absorption (Cu and Zn uptake related)
implicated in alzheimer's disease
can affect cholesterol and lower HDLs

2

Iodine

require about 150 micrograms/day
concentrates in Thyroid
usually bound to tyrosine residues of proteins - regulates metabolic rates in cells

3

Iodine deficiency

spontaneous abortion
birth defects
irreversible impairment of brain and physical development
stimulates enlargement of thyroid (goiter)

4

Iodine excess

Mild excess (up to 2 mg/day) no apparent effects
chronic excess can disrupt thyroid function

5

Selenium

enzyme cofactor for antioxidant defense
thyroid hormone and insulin function
regulation of cell growth and fertility
Exists as selenomethionine and selenocysteine
adults require about 55ug/day

6

Selenium deficiency

cardia failure
liver disease
cancer
atherosclerosis
hair loss
skin changes
infertility

7

Selenium Excess

>400 ug/day
peripheral neuropathy
nausea
diarrhea
dermatitis
hair loss
nail deformities

9

Homeostatic mechanisms act to maintain;

Optimal ionic strength

10

How do you estimate total body water (TBW)?

TBW (liters) = body weight (lbs) / 4

11

What are some macronutrients?

Water and salts
Minerals
Vitamins

12

What is a cofactor?

Organic (vitamins) or inorganic (metal) aids to enzymes

13

Selenium is said to be an antioxidant, but what is an issue that can arise because of this belief?

Selenium is toxic at high levels

14

Transcellular refers to...

Luminal fluid of GI tracts and CNS, fluid in eyes and lubricating fluids of serous membrane surfaces

15

Interstitial refers to...

Space between cells

16

Which is higher in the resting cell; K+ or Na+?

K+ (140 mM)

17

Osmotic equilibrium;

Extracellular fluid (ECF) osmolality = Intracell (ICF)

18

What is the particle concentration of a fluid called and what are it's units?

Osmolality Millosmoles per kg

19

Normal extracellular concentration of Na?

145 mM

20

Normal Intracellular concentration of Na?

12 mM

21

Normal Extracellular concentration of K?

4 mM

22

Normal Intracellular concentration of K?

140 mM

23

Major ECF solutes?

Na+, Cl- and HCO3

24

Major ICF solutes?

K+, organic phosphate esters (ATP, creatine phosphate, phospholipids)

25

what molecule is responsible for most of the osmotic pressure in blood?

Albumin contributes to ~80%

26

whats a milliequivalent?

still not sure but slides say= milliMolar when only one ionizable group = 2x mMolar if there are TWO charges if there are multiple ionizable groups with diff. pK's, it is more pH dependent

27

what is the normal osmolality of plasma ?

275-290 mosmol/kg

28

what is the recommended intake of sodium?

2400 mg/day

29

In 20% of the population is Na sensitive and can lead to . . .

hypertension (ECF expansion)

30

Which molecules regulate the effective osmolality of the ECF and the ICF respectively?

Na+, K+

31

What are the main macromolecules?

Sodium and potassium

32

When food is ingested, your cells become _____ so if you vomit you ____ solutes.

Isotonic, solutes

33

The GI tract to the jejunum ____ water and the jejunum to the colon ____ water.

Secretes, absorbs

34

What are the other important macromolecules?

Calcium, phosphorous, sulfer and magnesium

35

What are the functions of calcium?

Regulation of intracellular enzyme activities
Secretory processes
Blood clotting
Muscle contraction
Bone growth
Binds to proteins
Acts as second messenger
Hormone receptor interactions
Calmodulin Binding - regulates muscle contraction and inflammation

36

Calcium concentration higher inside or outside of a cell?

Intracellular calcium is ~0.1 uM
which is about 10,000x lower than the ECF

37

Example of symport

diffusion of H+ along gradient pulls along Lactose

38

How much water is lost with feces ?

100ml/day

39

why do you lose solutes if you vomit or have diarrhea?

ingested food/water become isotonic
diarrheal fluid is also close to being isotonic and can lead to loss of liters

40

Recommended K+ intake

3500 mg/day

41

Excess K+

cardiac arrest
K:Na ratio linked to hypertension

42

K+ deficiency

heart arrhythmia
muscle weakness
increased blood pH (alkalosis)

43

Example of Calcium acting in hormone receptor interaction

epi "fight or flight" hormone released from adrenal medulla. Binds to alpha receptors in liver, activates glycogenolysis and inhibits glycogen synthesis mainly by raising Ca+ levels in the liver

44

what promotes Ca+ absorption?

Vitamin D
Gastric acid
Lactose
Citrate, malate
Protein and phosphorous
Exercise

45

What inhibits Ca+ absorption?

Oxalic acid and Phytic acid from plants
Dietary fiber
Phosphate (combines with Ca+ to make insoluble precipitate - stones)
steatorrhea (fatty feces) (soaps)
increased rate of passage

46

what can occurs due to Calcium deficiencies?

rickets, osteomalacia - adult rickets
Vitamin D prevents rickets - low leads to poor intestinal absoprtion/poor kidney reabsorption of Ca and Phosphate
Osteoporosis

47

Many metal-phosphates are extremely ...

insoluble

48

Excessive Calcium intake leads to

risk of renal stone formation in some ppl

49

adult males should consume ~ _____ mg/day of calcium?

1000

50

What is the second most abundant mineral in the body?

Phosphate - (PO4)-3

51

where is most of the phosphate in the body ?

85% in bones and teeth
15% elsewhere - like nucleic acids

52

What regulates phosphate?

Vitamin D

53

what are some functions of phosphate?

in structure of nucleic acids
phospholipids
activation of enzymes by phosphorylation
ENERGY - ATP
acid-base balance

54

what are some dietary sources of Phosphate?

Animal protein, milk, eggs
Processed foods - tons of phosphate buffers
Food additive for pH adjustment, to sequester some thing (like metals)

55

what is the recommended daily intake of Phosphate?

700-1250mg/day

56

A high Ca:P ration promotes?

Ca excretion
15g/kg of diet is upper limit

57

What are some functions of Magnesium ?

Bone strength
ATP hydrolysis - most enzymes need Mg+2 to stabilize ATP
Enzyme cofactors
Binds nucleic acids
muscle relaxation after contractions

58

RDA for magnesium?

400mg/day male
300mg/day female

59

What are sources of Mg?

vegetables, nuts, legumes
~30-50% of intake is absorbed

60

Intracellular or extracellular Mg concentration higher?

intracellular

61

Mg deficiency

rare except with alcoholics
leads to hypertension, vascular disease. preeclampsia, osteoporosis

62

Mg excess

anaesthetic effect
diarrhea

63

function of sulfur?

sulfate in tissues
in AA - cysteine, methionine
key in disulfide bonds
role in transfer groups (Acetyl CoA)

64

Key metals in enzymatic activites and protein structure?

Iron
Zinc
Iodine
Selenium

65

Function of Iron

catalysis and electron transfer, oxygen transport

66

Why is Iron toxic in presence of oxygen ?

catalyzes Haber-Weiss-Fenton reactions

67

Haber-Weiss-Fenton reaction

Iron(II) + oxygen goes to Superoxide
Superoxide reacts with Hydrogen ions to make Hydrogen peroxide and oxygen
Iron(II) and hydrogen peroxide react to make hydroxyl radical (which attacks proteins) and hydroxide and Iron(III)

68

Zinc finger

protein domain that binds DNA for gene expression
cys, His, glutamate

69

Zinc

key role in many enzymes - catalysis and structure
Zinc fingers
Highly regulated by body
lose about 1mg/day

70

Unlike Fe, Zinc is NOT

redox reactive

71

What increases zinc absorption?

by binding to His, Cys and nucleotides

72

What decreases zinc absorption?

Phytate - attracts + metals

73

Metallothionein

Cys rich proteins bind many metals at high capacity (12 atoms per protein) - liver, stomach, brain, tongue
regulates Zn transfer in blood

74

what form of Zn is absorbed ?

Zn+2

75

Zinc storage

Men store 2.5 g
women 1.5 g
mainly in muscle and bone

76

Zinc turnover

300 days
very slow
In liver Zn-Mth is fast, ~2 weeks

77

units of trace metals in the body?

ppb - parts per billion = ug/liter
ppt - parts per trillion = ng/liter