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Vitamins PHM > Water soluble vitamins > Flashcards

Water soluble vitamins Flashcards

1
Q

Metabolicallly active form of Vit B1

A

TPP (thiamine pyrophosphate)

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2
Q

Which enzyme activates Thiamine into its active form?

A

thiamine pyrophosphotransferase

Thamine + ATP —–> TPP + AMP

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3
Q

Location of thiamine pyrophosphotransferase?

A

Brain and liver

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4
Q

Vit B1 metabolic function

A

A component of its metabolically active form which is a cofactor (co-enzyme) needed for many dehydrogenase enzymes like pyruvate dehydrogenase, transketolase, and ketoacid dehydrogenase all involved in decarboxylation of alpha ketoacids

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5
Q

How does Thamine defiency affect metabolic pathways?

A

Pyruvate can’t be converted to acetyl-CoA by pyruvate dehydrogenase so the Krebs cycle can’t generate ATP

Stops the HMP shunt from regenerating glucose-6-P because transketolase cannot function leading to accumulation of pentose sugars and no production of NADPH, since glucose6P is not being formed, which is needed by RBCs for glutathione to form = anemia. Also accumulation of the pentose sugar ribose 5 phosphate increases synthesis of purines

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6
Q

Deficiency of Thiamine symptoms

A
  1. Cerebral beriberi/Wernicke-korsakoff syndrome
    - damage to thalamus and hypothalamus (confusion, memory loss/confabulation, ataxia, ophthalmoplegia, nystagmus)
    - brain affected due to impaired glucose breakdown=impaired ATP levels
  2. Dry beriberi
    - nerves (Polyneuritis) and muscles affected = symmetrical wasting of muscles
  3. Wet beriberi
    - heart and circulatory system affected = cardiac failure and edema
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7
Q

Sources of Thiamine

A

Beek
Eggs
Peas
Nuts and seeds

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8
Q

Diagnostic tests for measuring thiamine deficiency

A
  1. Use of pyruvate: lactate ratio
    - lactate is fairly constant. in vit B1 deficiency, ratio is high because pyruvate not being converted into acetyl-CoA
  2. Checking Transketolase activity
    - Hemolysis of erythrocytes followed by dividing the blood sample into two sets. One set gets pentose sugars added and the other gets TPP + pentose sugars. Normal individuals with the 1st set will have normal activity of transketolase and addition of TPP will increase activity only by 0-15%. In deficient individuals, the 1st set will have very low transketolase activity, but when TPP is added to the 2nd set, activity increases from 15% - 100%
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9
Q

Function of Vit B2/Riboflavin

A

Acts as cofactor (specifically a cofactor) needed in redox reactions

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10
Q

Physical properties of Riboflavin

A

Bitter taste
Odorless
Is yellow

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11
Q

Which sugar attaches to the flavin moiety of riboflavin?

A

Ribitol

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12
Q

Deficiency of Riboflavin

A

Tongue is unusually smooth and purplish
Cheilosis (dry lips)
Angular stomatitis (tearing at corners of mouth)
Seborrheic dermatitis (common in the scalp; chronic form of eczema)
Corneal vascularization

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13
Q

Determination of riboflavin deficiency

A

Glutathione reductase needs FAD in order to use NADPH to generate glutathione.

…

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14
Q

Function of Vit B2/Riboflavin

A

Acts as precursor of cofactors (specifically a cofactor) needed in redox reactions; for synthesis of FMN and FAD

Necessary in conversion of Pyridoxine into Pyridoxal

Necessary for conversion of tryptophan into niacin

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15
Q

Physical properties of Riboflavin

A

Bitter taste
Odorless
Is yellow

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16
Q

Which sugar attaches to the flavin moiety of riboflavin?

A

Ribitol

17
Q

Ariboflavinosis

A

Tongue is unusually smooth and purplish
Cheilosis (dry lips)
Angular stomatitis (tearing at corners of mouth)
Seborrheic dermatitis (common in the scalp; chronic form of eczema)
Corneal vascularization
Hypothyroidism (as lack of riboflavin impairs formation of T3 and T4 hormones)

18
Q

Effect of hypothyroidism on FAD levels

A

Causes a decrease because TH is needed to stimulate FAD pyrophosphorylase enzyme

19
Q

Hormones influencing formation of FMN and FAD

A

Thyroid hormone, Aldosterone, and Adrenocorticotropic hormone stimulate riboflavin’s conversion to FMN and FAD

20
Q

Ariboflavinosis is associated with deficiency of which other vitamins and why?

A

Niacine and Pyridoxal (aldehyde form of pyridoxine)

Because FMN and FAD are needed for conversion of Pyridoxine into Pyridoxal. Then since Pyridoxal is needed for conversion of tryptophan into niacin, niacin can’t be formed leading to its deficiency as well

21
Q

Explain interaction between thyroid hormones and riboflavin.

A

Thyroid hormones stimulate its conversion to FAD while riboflavin stimulates formation of Thyroid hormones. So they have a kind of positive feedback relationship

22
Q

How does Phenothiazine affect conversion of riboflavin?

A

It’s a tranquillizer.

By blocking flavokinase, prevents conversion of riboflavin into FMN

23
Q

Niacin is derived from

A

tryptophan

24
Q

Function of niacin

A

Precursor for NAD and NADP coenzymes for redox reactions

Needed for synthesis of macromolecules

Facilitates DNA repair

Lowers levels of VLDL and increases levels of HDL

25
Q

Niacin, considering its ability to lower VLDL and elevate HDL, can be used to treat certain conditions. Explain one of your choice.

A

Dyslipidemia is characterized by high levels of cholesterol/lipids in blood.
Administration of Niacin results in reduction of these levels reducing chances of atherosclerosis and heart attacks

26
Q

True or False: Niacin is not a vitamin

A

True. It’s not considered a true vitamin since it can be synthesized from tryptophan

27
Q

Deficiency of Niacin

A

Pellagra (diarrhea, nausea, vomiting, dementia, dermatitis, hyperpigmentation of skin areas exposed to sun)

Photosensitive dermatitis
Depressive Psychosis
Hyperglycemia
Hyperuricemia
Facial flushing (caused by prostaglandin)
Seen in alcoholics, during pregnancy and lactation, and in people whose diet is low in tryptophan

28
Q

How much tryptophan required to produce how much niacin?

A

60 mg tryptophan = 1 mg niacin

29
Q

Daily recommendation of niacin intake

A

10-20 mg/day

30
Q

Explain cooling effect of smoking cigarettes

A

Cigarettes contain nicotine which causes release of serotonin. Serotinin causes vasodilation

31
Q

Panthothenic acid function

A

component of coenzyme-A and fatty acid synthase

32
Q

Deficiency of Vit B5

A
  1. Addison’s disease caused by Adrenal gland’s inability to make its steroid hormones (cortisol and aldosterone)
  2. Dermatitis
  3. Alpecia
  4. Enteritis (inflammation of small intestine = diarrhea)
33
Q

Most common form of Vit B6

A

Pyridoxine

34
Q

Functions of Vit B6

A

Important in transamination reactions of amino acids

Important for decarboxylation reactions for synthesis of neurotransmitters

Needed for heme synthesis

35
Q

Why is Vit B6 an “energy releasing” vitamin?

A

Necessary for catabolism of amino acids which releases energy

Vitamins PHM (3 decks)

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