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Metabolism > Micronutrients > Flashcards

Micronutrients Flashcards

1
Q

What three metal ions are essential micronutrients?

A

Copper, zinc, iron

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2
Q

What are micro and macronutrients?

A

Macronutrients: energy yielding e.g. fat, carb

Micronutrients: include vitamins and minerals

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3
Q

What are vitamins?

A

Small organic molecules that can’t be made by body, so obtained from diet

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4
Q

How can interactions between trace metal affect homeostasis?

A

Can affect each others oxidation state, leading to increased uptake or release.

For example iron is uptaken better in ferrous Fe3+ state. Cu changes Fe to 3+ state

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5
Q

What is the recommended dietary intake of Zinc?

A

Dietary intake: 8mg for women, 11mg for men

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6
Q

How is zinc distributed in the body?

A

Distribution: 1-2g in body, any in plasma mainly bound to albumin.

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7
Q

What is the role of zinc?

A

Role: DNA/RNA polymerases, alkaline phosphate, carboxypeptidase, transcription factors

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8
Q

What is the recommended dietary intake of copper?

A

Intake: 900 microgram per day

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9
Q

How is copper distributed in the body?

A

100mg in body, mainly in skin, muscle , bone marrow.

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10
Q

What is the role of copper?

A

Caeruloplasmin involve in Fe homeostasis

Connective tissue synthesis

Cytochrome oxidase

Superoxide dismutase

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11
Q

What is the recommended dietary intake of iron?

A

Males: 8mg
Females: 18mg
Pregnant females: 27mg

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12
Q

How is iron distributed in the body?

A

Hemoglobin: heme proteins and accounts for greater than 65% of body iron.

Non-haem iron enters circulation across small intestine

25% stored as ferritin

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13
Q

What chelates to iron inside the cell?

A

Ferritin

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14
Q

How much stored iron to males and females have?

A

Males 1000mg

Females 300mg

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15
Q

What is the role of iron?

A

Haemoglobin and myoglobin function. Essential for transferring oxygen from the lungs to the tissues. Myoglobin, in muscle cells, stores, and releases oxygen.

Component of certain proteins, essential for respiration and energy metabolism, and as a component of enzymes involved in the synthesis of collagen and some neurotransmitters.

Iron is needed for proper immune function.

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16
Q

How much ingested iron is absrorbed?

A

5% to 35% depending on circumstances and type of iron.

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17
Q

What carries iron in Fe3+ state between absorption storage and utilisation sites?

A

Transferrin

18
Q

What is the role of hepcidin?

A

Regulates iron balance, binds to the transferrin receptor (FNP1)

19
Q

What happens when levels of hepcidin increase?

A

Negatively regulates iron balance, reduces iron absorption

Iron in macrophages is increased and GI iron is decreased.

20
Q

What happens when iron levels are low (regulatory)?

A

Hepcidin levels are low, iron released from stores and more absorbed

21
Q

Compare water soluble and fat soluble vitamins?

A

Water soluble: usually coenzyme precursors

Fat soluble: only absorbed in presence of dietary fat

22
Q

What is role of niacin (vitB3)?

A

Precursor of NAD+ and NADP (cofactor for dehydrogenase reactions i.e in glycolysis and TCA cycle)

23
Q

What is role of riboflavin

(vitB2)?

A

Precursor of FAD/FMN cofactor for dehydrogenase reactions e.g. FAD part of succinate dehydrogenase, FMN part of complex I

24
Q

What is role of pyridoxine

(vitB6)?

A

Precursor of pyridoxal phosphate - cofactor for transamination and decarboxylation

25
Q

What is thiamine

(vitB1)?

A

Precursor of thiamine pyrophosphate, cofactor for PDH (catalyses pyruvate to acetyl CoA) and alpha ketoglutarate dehydrogenase

26
Q

What are roles of folic acid (vitB9)?

A

Involved in purine and pyrimidine biosynthesis

27
Q

What is symptom of folic acid deficiency?

A

Neural tube defect, megaloblastic anaemia

28
Q

What is role of vitB12?

A

Cofactor in DNA synthesis, FA and AA metabolism important for nervous system functioning

29
Q

How is vitamin B12 absorbed?

A

Absorbed using intrinsic factor from parietal cells

30
Q

What is the deficiency of niacin?

A

Pellagra
Characterized by diarrhea, sun-sensitive dermatitis, dementia, hyperpigmentation, amnesia, delirium, and eventually death, if left untreated.

31
Q

What is the deficiency of riboflavin?

A

Riboflavin deficiency (similar to pellagra)

Painful red tongue with sore throat, chapped and fissured lips. Oily scaly skin rashes. The eyes can become itchy, watery, bloodshot and sensitive to light.

Anemia with normal cell size and normal hemoglobin content (i.e. normochromic normocytic anemia).

Congenital heart defects and limb deformities.

32
Q

What is the deficiency of pyroxidine?

A

B6 deficiency
Characterized by weakness, irritability and nervousness, insomnia, and difficulty in walking.

Cheilosis (cracks at the corners of the mouth) that is not responsive to biotin or riboflavin

Infants consuming B6 -deficient milk formula have convulsive seizures

33
Q

What is the deficiency of thiamine

A

Beri Beri

It is characterized by ophthalmoplegia, sixth nerve palsy, nystagmus, ptosis, ataxia, confusion, and coma, which may terminate in death.

Oftentimes, the confusional state persists after treatment of the acute thiamin deficiency. This is known as Korsakoff’s psychosis.

34
Q

Where is beri-beri most seen?

A

In alcoholics who consume alcohol in preference to food and thus have a minimal intake of thiamin.

35
Q

A cofactor for enzyme-catalysed carboxylation reactions

A

Biotin (B7)

36
Q

The consequences of severe iron deficiency

A

Hypochromic, microcytic anaemia

37
Q

What is a sensitive indicator of depletion of body iron stores?

A

Serum ferritin

38
Q

In people consuming a corn-based diet that is marginally adequate, what problem would they develop?

A

Pellagra

39
Q

What amino acid has a positive effect on niacin deficiency?

A

Tryptophan

40
Q

The absorption of Vitamin B12 from the gastrointestinal tract is dependent on?

A

Transcobalamin

Intrinsic factor

Metabolism (13 decks)

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