Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ASC378 > B-Complex Vitamins > Flashcards

B-Complex Vitamins Flashcards

1
Q

Most B vitamins are ________ in ________ ___________ __________

A

coenzymes; cellular enzyme metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

General B-complex deficiency symptoms

A

-loss of appetite (anorexia)
-poor growth
-emaciation
-nerve related disorders
-dermatitis
-anemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Vitamin B1

A

Thiamine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the principle role of Thiamine?

A

part of the coenzyme cocarboxylase (TPP)
-TPP is the coenzyme for at least 24 enzyme systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Thiamine is closely related to _______ ________

A

Lipoic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Lipoic acid

A

an essential component of a “multienzyme” system which is involved in the oxidative decarboxylation of keto acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What occurs with pyruvic acid before its entrance into the TCA cycle?

A

it must be decarboxylated and then combined with coenzyme A to form acetyl CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens in the absence of Thiamine?

A

reactions do not proceed at a normal rate so pyruvic acid and lactic acid accumulate in the blood and tissues
-this increase in acids is responsible for deficiency symptoms in metabolically active tissue like muscle and nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Beriberi

A

-thiamine deficiency disease in humans
-extensive damage to nervous and cardiovascular systems
-severe muscle wasting (dry beriberi
-edema (wet beriberi)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Polyneuritis

A

-Thiamine deficiency disease
-in birds
-accumulation of intermediates of CHO metabolism
-a peripheral nerve degeneration as evidenced by the breakdown of the myelin sheaths of the nerve fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Thiamine deficiency symptoms

A

-beriberi
-polyneuritis
-soft muscles
-anorexia or loss of appetite
-weight loss
-bradycardia (reduced heart rate) and enlargement of heart

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Thiamine requirements are influenced by

A

carbohydrate intake and caloric intake

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Thiamine is readily destroyed by ________ in the presence of moisture

A

heat (cooking)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Thiamin deficiency in North America is largely associated with…

A

chronic alcoholism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where is Thiamine absorbed?

A

small intestine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens to thiamine after it is absorbed?

A

carried to the liver and phosphorylated to form TPP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Where is thiamine stored?

A

it is not stored and must have a daily intake (except for in the pig)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is thiamine’s role in ruminants and horses?

A

-in a functional rumen bacterial synthesis of B1 is adequate
-in the cecum and LI of the horse bacterial synthesis occurs
-synthesis is not adequate for nutritional needs alone, dietary intake is still necessary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Pyrithiamine

A

-antivitamin of thiamine
-competes with thiamine for incorporation into the enzymes thus rendering the enzyme inactive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Chastek paralysis

A

-in foxes
-due to an antagonistic action of thiaminase
-similar to “bracken fern poisoning” in horses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Thiamine sources

A

-mainly from plants
-yeasts (richest)
-molds
-leaves of grasses
-germ of cereal grains
-seed coats of grains
-pork has 100x the amount in beef

22
Q

Vitamin B2

A

riboflavin

23
Q

What 2 coenzymes does riboflavin act as

A

-FMN - flavin mononucleotide (1 phosphate group)
-FAD - flavin adenine dinucleotide (2 phosphate groups)

24
Q

What are the flavin coenzymes concerned with?

A

donating and accepting H atoms
-FAD function with the enzyme succinic dehydrogenase

25
Q

What other enzymes is FAD a constituent of?

A

-D-amino acid oxidase
-glycine oxidase
-xanthine oxidase (purine to uric acid)

26
Q

What is different about the symptoms of riboflavin deficiency to thiamine deficiency?

A

it is not possible to relate the symptoms to the biochemical roles of riboflavin

27
Q

Riboflavin deficiency symptoms

A

-decrease growth
-alopecia or hair loss in rats
-opaque cornea or cataracts in humans
-curled toe paralysis in chicks
-low egg production and hatchability
-skin and eye symptoms in man

28
Q

What are the skin and eye symptoms of riboflavin deficiency in humans?

A

-cheilosis = roughened skin and furrows around the mouth
-dermatitis = due to overactivity of sebaceous or oil glands and results in waxy dermatitis of eyes, ear lobes, and mouth
-corneal vascularization = due to increase blood vessels in the eye

29
Q

Where is riboflavin phosphorylated?

A

in the intestinal wall

30
Q

After phosphorylation what happens to riboflavin?

A

it is carried by the blood to the cells of the tissues where it occurs as the phosphate or as a flavoprotein

31
Q

Where is riboflavin stored?

A

storage is small and excessive intakes are rapidly excreted in urine

32
Q

Sources of riboflavin

A

-yeast (richest)
-milk
-leafy portions of plants like alfalfa
-eggs, liver, heart, kidney, and meat muscle (richest animal products)
-whey and distiller’s solubles

33
Q

What/Who synthesizes riboflavin?

A

-higher plants
-yeasts
-fungi
-some bacteria
-ruminants synthesize inadequate amounts
-horses synthesize inadequate amounts in cecum

34
Q

Vitamin B6

A

pyridoxine

35
Q

What results in substantial loss of the 3 pyridoxine compounds?

A

sterilization of milk

36
Q

Three forms of vitamin B6

A

-pyridoxine
-pyridoxal
-pyridoxamine

37
Q

What are the active forms of vitamin B6

A

pyridoxal phosphate and pyridoxamine phosphate
(pyridoxal is the most active)

38
Q

Where are the forms of B6 phosphorylated?

A

in the liver after absorption
(once phosphorylated, interconversion is possible)

39
Q

What does pyridoxal phosphate mainly function as?

A

a coenzyme in several enzyme systems concerned with protein/amino acid metabolism

40
Q

Pyridoxal phosphate is necessary in the process of ___________

A

transamination

41
Q

Transimination

A

a process that involves the transfer of the amino group to keto acids
-most abundant catalyze transamination of glutamic acid to oxaloacetic and pyruvic acids

42
Q

Pyridoxal phosphate is involved in ______________ reactions

A

decarboxylation
-serves as a coenzyme (codecarboxylase) which decarboxylates several amino acids
-more abundant in microorganisms than animal tissues

43
Q

B6 is involved in the synthesis of ________ from ___________

A

niacin from tryptophan

44
Q

In the absence of B6 what forms instead of niacin?

A

xanthurenic acid is formed and excreted in the urine
-level of this metabolite in urine can be used as an indicator of B6 nutrition

45
Q

What are the two antivitamins of B6?

A

-desoxypyridoxine
-isoniazid (drug used in the treatment of tuberculosis)
-compete with B6 for the active site on the apoenzyme

46
Q

Vitamin B6 deficiency symptoms

A

-growth failure
-acrodynia (dermatitis) in rats
-urinary calculi (especially in cattle)
-anemia in dogs, pigs, and rats
-convulsions or epileptic seizures
-slow growth and suppressed appetite

47
Q

Acrodynia

A

-dermatitis of tails, ears, mouth, and paws accompanied by an edema
-the edema distinguishes acrodynia from dermatitis of essential fatty acid deficiency

48
Q

Urinary calculi

A

-due to defect in glycine metabolism
-high insoluble Ca oxalate precipitates out as “stones” in kidney and urinary tract

49
Q

What causes the anemia caused by vitamin B6?

A

inability to condense glycine with succinyl CoA to form a-amino-B-ketoadipic acid which is the initial step in heme synthesis so microcytic hypochromic anemia results

50
Q

Sources of B6

A

-yeast
-liver
-muscle meat
-milk
-cereal grains
-food supply is usually so rich in B6 that practical rations are very unlikely to cause deficiency

ASC378 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions