Lecture 18: Minerals Flashcards Preview

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Flashcards in Lecture 18: Minerals Deck (65):
1

What are the nine essential macro minerals?

Ca
P
Mg
S

K
Na
Cl

2

What are the 9 essential trace minerals?

Iron
Zinc

Copper
Manganese

Fluoride
Iodine

Selenium
Molybdenum

Chromium

3

What are the functions and daily requirements of phosphorus?

Bone stability
Cell signaling
Component of ATP, DNA, RNA, phospholipids

700 mg/day

4

What are the functions and daily requirements of magnesium?

Cell metabolism (ATP synthesis !!)
Muscle contraction
Blood clotting

300-400 mg/day

5

What are the functions of sulfur?

Critical for protein function and cell metabolism

Component of organic molecules

6

How do Ca, P, Mg, and S get taken up into the intestine?

Ca = active, passive absorption

Mg = active, passive absorption

P = active

S = part of organic molecules

7

Where is there active absorption of calcium?

Duodenum

8

What mediates calcium uptake into the intestines?

TRPV6

Important for low concentrations of Ca

9

What factors increase TRPV6 expression and activity?

vitamin D3

10

How is calcium actively exported ?

Ca ATPase

11

When is passive intestinal calcium absorption important?

Normal and high calcium levels

12

What are major regulators of calcium homeostasis and their effects?

Vitamin D = inc. calcium

Parathyroid hormone = inc. calcium

Calcitonin = dec. calcium

13

What are causes of calcium deficiency ?

Inadequate intake

Impaired absorption due to small intestinal inflammation (celiac disease, IBD)

14

what are symptoms of calcium deficiency?

Osteoporosis

15

What is the treatment for calcium deficiency?

Dietary adjustments, calcium supplements

16

What chronic diseases are associated with calcium?

Low calcium = inc. risk for HPT

More calcium = lower risk for colon cancer

17

What is the safe upper limit of calcium to reduce risk of hypercalcemia?

2-3 g/day

18

What is hypercalcemia?

Associated with increased risk of

Kidney stones
Calcification of soft tissues
Kidney failure

19

What are food sources of phosphorus?

Milk
Meat
Eggs

20

Is there passive absorption of phosphorus?

No

21

Where does phosphate absorption take place?

Duodenum and jejunum

22

How is phosphorus taken up into the cell?

Na-dependent phosphate cotransporter (SLC)

23

What are causes of phosphate deficiency?

Dietary insufficiency = RARE

Impaired intestinal absorption (from Al-containing antacids)

Renal disorders

24

What are the symptoms of phosphate deficiency?

Neuromuscular = weakness, lethargy, bone pain

25

What is the treatment for phosphate deficiency?

Infusion therapy + treatment strategy for underlying disease

26

What food sources does magnesium come from?

Whole grains

Vegetables

Legumes

27

What does magnesium do?

Participates in a lot of metabolic reactions:

DNA and protein synthesis

28

Where is magnesium absorbed?

Jejunum and ileum

29

How does magnesium get taken up into cell actively?

Magnesium channel = TRPM6/7

30

How is Mg excreted actively?

Mg/Na exchanger

31

Is Mg brought into the cell passively?

Yes @ high [Mg]

32

What are causes of magnesium deficiency?

Renal diseases

Alcoholism

Protracted diarrhea, vomiting

Some diuretic drugs

Dietary deficiencies very RARE

33

What are symptoms of magnesium deficiency?

N/V

Neuromuscular and psychiatric symptoms

34

What is the treatment for magnesium deficiency ?

Oral magnesium salts

Treat underlying problem

35

What are the clinically most important trace minerals?

Iron

Zinc

Copper

Iodine

36

What are the dietary requirements of trace minerals?

<100 mg/day

37

What are common trace mineral deficiencies?

Iron

Zinc

Iodine

38

What are the functions of iron, zinc, copper and iodine?

Fe = oxygen transport, enzyme functions

Zn = enzyme functions

Cu = enzyme functions

I = thyroid hormones

39

Characterize intestinal uptake of the clinically important trace minerals (Fe, Zn, Cu, I)

Active transport of ionized forms

40

What food sources does iron come from?

Meats

Legumes, whole grain, enriched grains

41

Is there a passive paracellular pathway for intestinal absorption of iron?

No

42

Is there a passive paracellular pathway for intestinal absorption of copper?

No

43

Where does absorption of iron occur?

Duodenum and proximal jejunum

44

What must happen before iron can be absorbed?

Iron needs to be reduced to Fe2+

45

How is iron taken up by cells?

Proton-coupled divalent metal transporter = DMT1

46

How is iron exported?

Ferroportin = SLC40A1

Iron gets oxidized for transportation!

47

What is transferrin?

Oxidized iron + apotransferrin

Found in circulation

48

What is ferritin?

Iron storage complex

Forms when there is excess intracellular iron

49

Why is ceruloplasmin important?

Oxidizes iron so it could be ready for transport via transferrin

50

What is hepcidin and what does it do?

Hepcidin is a peptide hormone made in the liver when there is high iron and inflammation

Hepcidin will induce ferroportin degradation to block iron export from epithelial cells

51

What are causes of iron deficiency?

Nutritional deficiency

Decreased iron intake/absorption: inadequate diet*, malabsorption due to small intestine destruction, systemic inflammation

Inc. iron loss: menses, acute and chronic blood loss

Inc. iron demand: pregnancy, infancy, adolescence

52

What are symptoms of iron deficiency?

Anemia

Fatigue

Headache

Growth impairment

53

What is the treatment for iron deficiency?

Dietary modifications

Oral iron therapy

Parenteral iron therapy

54

Describe iron overload and toxicity

Hemochromatosis (from genetic defects in hepcidin, etc)

Characterized by: excess iron storage in liver, pancreas, adrenals and thyroid

Too much iron absorption without enough excretion

55

Why is too much iron bad?

Oxidative damage to membranes, proteins, DNA

Particularly to liver and heart

56

What are food sources of copper?

Meats (liver)
Shellfish
Nuts
Seeds
Legumes
PB
Chocolate

57

What is copper important for?

Required for oxidation of iron (for iron absorption)

Neural development + function

Oxidant scavenging

58

How is copper taken up into cell?

Copper transporter 1 (CTR1)

59

How is copper exported?

Copper transport ATPase (ATP7A)

60

What is copper mostly found bound to in the plasma?

Ceruloplasmin

61

Loss of which transporters can lead to copper-related diseases?

ATP7A => Menkes disease

ATP7B => Wilson disease

62

What does loss of ATP7A affect?

Intestine, kidney, brain

63

What does loss of ATP7B affect?

Liver, brain

64

How do loss of ATPases relate to copper levels?

ATP7A loss = too little copper

ATP7B loss = too much copper

65

Is there passive paracellular uptake of sulfur?

No