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FA - Biochemistry > Biochem - Nutrition (Part 1: Vitamins A and B1-7) > Flashcards

Biochem - Nutrition (Part 1: Vitamins A and B1-7) Flashcards

Pg. 91-93 in First Aid 2014 Sections include: -Vitamins: fat soluble -Vitamins: water soluble -Vitamin A (retinol) -Vitamin B1 (thiamine) -Vitamin B2 (riboflavin) -Vitamin B3 (niacin) -Vitamin B5 (pantothenate) -Vitamin B6 (pyridoxine) -Vitamin B7 (biotin)

1
Q

Name the fat soluble vitamins.

A

A, D, E, K

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2
Q

What do vitamins A, D, E, and K have in common in terms of their classification and absorption?

A

Fat soluble vitamins; Absorption dependent on gut and pancreas

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3
Q

Is toxicity more common water-soluble or fat-solube vitamins, and why?

A

Fat-soluble vitamins; Toxicity more common than for water-soluble vitamins because fat-soluble vitamins accumulate in fat

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4
Q

Give at least 3 examples of conditions/contexts that may cause fat-soluble vitamin deficiencies.

A

Malabsorption syndromes (steatorrhea), such as (1) cystic fibrosis and (2) sprue, or (3) mineral oil intake can cause fat-soluble vitamin deficiencies

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5
Q

Name 9 water soluble vitamins. Give their letter names and full names. Also, where applicable, include important molecules in which they are found.

A

(1) B1 (thiamine: TPP) (2) B2 (riboflavin: FAD, FMN) (3) B3 (niacin: NAD+) (4) B5 (pathothenic acid: CoA) (5) B6 (pyridoxine: PLP) (6) B7 (biotin) (7) B9 (folate) (8) B12 (cobalamin) (9) C (absorbic acid)

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6
Q

Which water soluble vitamins do not not wash out easily from the body, and why?

A

All wash out easily from body except B12 and folate (stored in liver)

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7
Q

What are 3 symptoms that often result from B-complex deficiencies?

A

B-complex deficiencies often result in (1) dermatitis, (2) glossitis, and (3) diarrhea.

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8
Q

What is another name for Vitamin A? Besides being a fat-soluble vitamin, what other kind of property/classification does it have?

A

Vitamin A (Retinol); Antioxidant

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9
Q

What is a good way to remember the other name for Vitamin A and one of its clinical uses?

A

Think: “RETINol is vitamin A, so think retin-A (used topically for wrinkles and acne)”

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10
Q

What are 2 sources of Vitamin A (retinol)?

A

Found in liver and leafy vegetables

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11
Q

What are 3 natural functions of Vitamin A (retinol)?

A

(1) Constituent of visual pigments (retinal); (2) Essential for normal differentiation of epithelial cells into specialized tissue (pancreatic cells, mucus-secreting cells); (3) Prevents squamous metaplasia.

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12
Q

What are 2 potentially serious conditions that Vitamin A (retinol) is used to treat?

A

Used to treat (1) measles and (2) AML, subtype M3.

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13
Q

What are 5 symptoms associated with Vitamin A (retinol) deficiency?

A

(1) Night blindness (nyctalopia); (2) Dry, scaly skin (xerosis cutis); (3) Alopecia; (4) Corneal degeneration (keratomalacia); (5) Immune suppression.

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14
Q

What are 7 symptoms associated with Vitamin A excess?

A

(1) Athralgias, (2) Skin changes (e.g., scaliness), (3) Alopecia, (4) Cerebral edema, (5) Pseudotumor cerebri, (6) Osteoporosis, (7) Hepatic abnormalities.

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15
Q

Which fat soluble vitamin is associated with teratogenic effects? What teratogenic effects may it have? What is an important clinical consideration related to this?

A

Teratogenic (cleft palate, cardiac abnormalities), so a negative pregnancy test and reliable contraception are needed before isotretinoin is prescribed for severe acne.

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16
Q

What is another name for Vitamin B1? In general, what is its function?

A

Vitamin B1 (thiamine); In thiamine pyrophosphate (TPP), a cofactor for several dehydrogenase enzyme reactions

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17
Q

What are 4 reactions for which Vitamin B1 (thiamine) functions as a cofactor?

A

In thiamine pyrophosphate (TPP), a cofactor for several dehydrogenase enzyme reactions: (1) Pyruvate dehydrogenase (links glycolysis to TCA cycle) (2) alpha-ketoglutarate dehydrogenase (TCA cycle) (3) Transketolase (HMP shunt) (4) Branched-chain ketoacid dehydrogenase; Think: “ATP: alpha-ketoglutarate dehydrogenase, Transketolase, and Pyruvate dehydrogenase”

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18
Q

What mechanism occurs in response to Vitamin B1 (thiamine) deficiency? Which tissues are affected first? Give 2 examples of such tissues.

A

Impaired glucose breakdown => ATP depletion worsened by glucose infusion; Highly aerobic tissues (e.g., brain, heart) are affected first.

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19
Q

What 2 conditions result from Vitamin B1 (thiamine) deficiency? In what other 2 conditions can this deficiency be secondary?

A

Wernicke-Korsakoff syndrome and beriberi. Seen in malnutrition and alcoholism (secondary to malnutrition and malabsorption). Think: “Spell beriberi as Ber1Ber1 to remember vitamin B1”

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20
Q

How is Vitamin B1 (thiamine) deficiency diagnosed?

A

Diagnosis made by increase in RBC transketolase activity following vitamin B1 administration.

21
Q

What 6 symptoms characterize Wernicke-Korsakoff syndrome? What causes it?

A

Wernicke-Korsakoff syndrome - (1) confusion, (2) ophthalmoplegia, (3) ataxia (classic triad) + (4) confabulation, (5) personality change, (6) memory loss (permanent); Vitamin B1 (thiamine) deficiency; Damage to medial dorsal nucleus of thalamus, mammillary bodies.

22
Q

What deficiency causes beriberi? What symptoms characterize dry versus wet beriberi?

A

Vitamin B1 (thiamine) deficiency; DRY BERIBERI - polyneuritis, symmetrical muscle wasting, WET BERIBERI - high-output cardiac failure (dilated cardiomyopathy), edema

23
Q

What is another name for Vitamin B2?

A

Vitamin B2 (riboflavin)

24
Q

What is (are) the major function(s) of Vitamin B2 (riboflavin)? Give a specific example.

A

Component of flavins FAD and FMN, used as cofactors in redox reactions, e.g., the succinate dehydrogenase reaction in the TCA cycle; Think: “Fad and Fmn are derived from riboFlavin (b2 = 2 atp)”

25
Q

What are 2 symptoms that result from Vitamin B2 (riboflavin) deficiency?

A

(1) Cheilosis (inflammation of lips, scaling and fissures at the corners of the mouth), (2) Corneal vascularization; Think: “the 2 C’s of b2”

26
Q

What is another name for Vitamin B3?

A

Vitamin B3 (niacin)

27
Q

Of what molecules is Vitamin B3 (niacin) a constituent, and in what reactions are such molecules used?

A

Constituent of NAD+, NADP+ (used in redox reactions); Think: “Nad derived from Niacin (b3 = 3 ATP)”

28
Q

From what substance is Vitamin B3 (niacin) derived? What does synthesis of Vitamin B3 (niacin) require?

A

Derived from tryptophan. Synthesis requires vitamins B2 and B6.

29
Q

What condition is Vitamin B3 (niacin) used to treat, and what effect(s) does it have in this context?

A

Used to treat dyslipidemia; lowers levels of VLDL and raises levels of HDL

30
Q

What is a classic symptom of Vitamin B3 (niacin) deficiency? What can be caused by severe B3 deficiency?

A

Glossitis. Severe deficiency leads to Pellagra (Symptoms of Pellagra: Diarrhea, Dementia [also hallucinations], Dermatitis [e.g., Casal necklace or hyperpigmentation of sun-exposed limbs]); Think: “the 3 D’s of b3”

31
Q

What are 3 conditions that may cause Pellagra, and what is the mechanism behind each?

A

Severe deficiency leads to pellagra, which can be caused by (1) Hartnup disease (decrease tryptophan absorption, (2) Malignant carcinoid syndrome (increase tryptophan metabolism), and (3) Isoniazid (decrease vitamin B6)

32
Q

What are the symptoms of Pellagra?

A

Symptoms of Pellagra: Diarrhea, Dementia [also hallucinations], Dermatitis [e.g., Casal necklace or hyperpigmentation of sun-exposed limbs]; Think: “the 3 D’s of b3”

33
Q

What are 2 presentations/examples of the dermatitis associated with Pellagra?

A

Dermatitis (e.g., Casal necklace or hyperpigmentation of sun-exposed limbs)

34
Q

What are 3 symptoms of Vitamin B3 (niacin) excess?

A

(1) Facial flushing (induced by prostaglandin, not histamine) (2) Hyperglycemia (3) Hyperuricemia

35
Q

What causes the facial flushing associated with Vitamin B3 (niacin) excess?

A

Facial flushing (induced by prostaglandin, not histamine)

36
Q

What is another name for Vitamin B5?

A

Vitamin B5 (pantothenate); Think: “b5 is ‘PENTO’ thenate”

37
Q

What is the function of Vitamin B5 (pantothenate)?

A

Essential component of coenzyme A (CoA, a cofactor for acyl transfers) and fatty acid synthase

38
Q

What are 4 symptoms of Vitamin B5 (pantothenate) deficiency?

A

(1) Dermatitis (2) Enteritis (3) Alopecia (4) Adrenal insufficiency

39
Q

What is another name for Vitamin B6?

A

Vitamin B6 (pyridoxine)

40
Q

To what is Vitamin B6 (pyridoxine) converted, and in what 3 processes is this a cofactor?

A

Converted to pyridoxal phosphate, a cofactor used in transamination (e.g., ALT and AST), decarboxylation reactions, glycogen phosphorylase.

41
Q

What are 9 substances synthesized using Vitamin B6 (pyridoxine)?

A

Synthesis of (1) cystathionine, (2) heme, (3) niacin, (4) histamine, and neurotransmitters including (5) serotonin, (6) epinephrine, (7) norepinephrine, (8) dopamine, and (9) GABA

42
Q

What are 4 symptoms of Vitamin B6 (pyridoxine) deficiency?

A

(1) Convulsions, (2) Hyperirritability, (3) Peripheral neuropathy (deficiency inducible by isoniazid and oral contraceptives), (4) Sideroblastic anemias due to impaired hemoglobin synthesis and iron excess

43
Q

What are 2 medications that may induce Vitamin B6 (pyridoxine) deficiency?

A

Convulsions, Hyperirritability, Peripheral neuropathy (deficiency inducible by [1] isoniazid and [2] oral contraceptives), Sideroblastic anemias due to impaired hemoglobin synthesis and iron excess

44
Q

What is another name for Vitamin B7?

A

Vitamin B7 (biotin)

45
Q

What are the 3 major enzymes and their reactions for which Vitamin B7 (biotin) serves as a cofactor? In general, what do all of these reactions accomplish?

A

Cofactor for carboxylation enzymes (which add a 1-carbon group): (1) Pyruvate carboxylase: pyruvate (3C) => Oxaloacetate (4C) (2) Acetyl-CoA carboxylase: Acetyl-CoA (2C) => Malonyl-CoA (3C) (3) Propionyl-CoA carboxylase: Propionyl-CoA (3C) => Methylmalonyl-CoA (4C)

46
Q

How common is Vitamin B7 (biotin) deficiency?

A

Relatively rare

47
Q

What are 3 symptoms associated with Vitamin B7 (biotin) deficiency?

A

(1) Dermatitis (2) Alopecia (3) Enteritis

48
Q

What are 2 causes of Vitamin B7 (biotin) deficiency?

A

Caused by (1) antibiotic use or (2) excessive ingestion of raw egg whites; Think: “AVIDin in egg whites AVIDly binds biotin”

FA - Biochemistry (31 decks)

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