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BIBC120 > Final - Lecture 10 > Flashcards

Final - Lecture 10 Flashcards

1
Q

Define ‘Vitamins’

A

Essential organic substances needed in trace quantities for normal growth, metabolism and function

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2
Q

Do vitamins directly yield energy?

A

No, but they facilitate energy-yielding processes.

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3
Q

What three physiological aspects are affected by vitamins?

A

metabolism, development and immunity

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4
Q

Vitamins are not inorganic nutrients. What are inorganic nutrients called?

A

Minerals.

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5
Q

What are the two classes of vitamins?

A

1) Water-soluble

2) Fat-soluble

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6
Q

How do the two classes of vitamins differ?

A

1) Water-soluble vitamins are excreted quicker from the body (storage time of 1-4wks)
* Exception VB12
2) Fat-soluble vitamins have larger storage pools (months-years)

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7
Q

Which class of vitamins more easily reaches levels of toxicity?

A

Fat-soluble

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8
Q

What happens to fat-soluble vitamin intake when lipid absorption in the small intestine is impaired by weight loss medicine?

A

The uptake is decreased.

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9
Q

What are the three key retinoids?

A 
Retinol (Most abundant) CH2(OH)
^Dehydrogenase
Retinal CHO (double bond on O)
^Dehydrogenase
Retinoic Acid COOH (C=O and OH)
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10
Q

What foods contain B-carotene, a carotenoid, in high quantities?

A

Fruits, Veggies (particularly carrots and yams) and leafy greens (dandelion leaves)

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11
Q

B-carotene can produce 2 of which retinoid?

A

Retinal

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12
Q

Name 3 of the 4 major functions of retinoic acids.

A

1) Acts as hormone/signal
2) Induce new gene expression
3) Needed for proper immune function in GI tract
4) Needed for structural integrity of tissues (esp. epithelial)

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13
Q

What do children with low vitamin A often experience?

A

Diarrhea as a result of gut immunity.

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14
Q

Acetaldehyde, an intermediate in the metabolism of alcohol, inhibits the function of what retinoid-associated enzyme?

A

Retinal dehydrogenase; reduces retinoic acid production

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15
Q

Name the 5 deficiency symptoms of Vitamin A.

A

(1) Night blindness, (2) Keratinization of epithelial tissue, (3) Xerophthalmia, (4) Infections, (5) Blindness

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16
Q

Describe the xerophthalmia condition.

A

Loss of mucus leads to dry eyes, and cornea sloughs off

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17
Q

How does a deficiency in vitamin A affect infections?

A

Immunity is impaired, esp. in the GI tract.

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18
Q

Describe keratinization of the epithelial tissue.

A

The skin becomes very rough because hair follicles make too much keratin. (Hyperkeratosis)

19
Q

What are some good sources of vitamin A?

A

Carrots, sweet potatoes and beef liver

20
Q

What animal vitamin has the greatest risk of toxicity? What is the UL? What are the symptoms of toxicity?

A

Vitamin A; 3000 micrograms RAE/day from animal sources; nausea, headache, dizziness, liver damage, hair and bone loss, birth defects and spontaneous abortion (teratogens)

21
Q

Vitamin A-based medicines typically contain Isotretinoin (Accutane) 13-cis-retinoic acid. How does this differ from retinoic acid?

A

the C=C connected to COOH is cis. Isotretinoin is widely used in treatment of severe acne, but is also highly teratogenic.

22
Q

How is consumption of fruits and veggies rich in B-carotene associated with lung cancer?

A

Sufficient consumption is correlated with reduced risk of lung cancer.

23
Q

How is consumption of B-carotene supplements associated with lung cancer in high risk groups (smokers)?

A

Higher rates of cancer was observed in high risk groups as compared to placebo groups.

24
Q

Synthesis of Vitamin D3 occurs in what parts of the body (In order)? Where is the active form produced?

A

Skin (UV step), liver, kidney; kidney (calcitrol)

25
Q

The UV-dependent step of Vitamin D3 synthesis is less efficient in which three groups of people?

A

Older people, people with dark skin, and people in areas with high smog.

26
Q

What are the three major functions of Vitamin D?

A

(1) Calcium homeostasis
(2) hormone effects (differentiation of skin cells)
(3) Inhibition of breast, colon, and prostate cancers. Promotes immunity in general.

27
Q

Describe Vitamin D’s influence on Calcium homeostasis.

A

Increases Ca absorption in intestine, supports bone growth in youth, promotes release of Ca from bones when Ca is low.

28
Q

What is the health benefit of vitamin D releasing Ca from bones when Ca is low?

A

Nerves and muscles need sufficient levels of Ca. Too low results in heart failure.

29
Q

What are three good sources of vitamin D?

A

fish, fortified milk, sunlight

30
Q

Describe the ‘Rickets’ condition.

A

Lack of Ca and P to mineralize bones; legs bow out, heads and ribs enlarge.
Can be cured early with Vit D and Ca treatments.

31
Q

What are the consequences of Vitamin D toxicity levels?

A

Ca becomes depleted in bones and Ca is deposited in soft tissues. This leads to bone malformations, calcification of soft tissues and kidney stones.

32
Q

What sources produce reactive oxygen species (free radicals)?

A

respiration, environmental toxins, immune system

33
Q

What are the beneficial properties of reactive oxygen species?

A

(1) used by immune system to kill pathogens; (2) used in apoptosis; (3) used for signaling

34
Q

What are the harmful properties of reactive oxygen species?

A

(1) produce harmful chain reactions; (2) destroy or modify nucleic acids, proteins and membranes; (3) increased inflammation and risk of cancer and CVD

35
Q

What reaction does superoxide dismutase catalyze?

A

2O2 -> H2O2 + O2

36
Q

What reaction does catalase catalyze?

A

2H2O2 -> 2H2O + O2

37
Q

What reaction does peroxidase catalyze?

A

H2O2 -> 2H2O

38
Q

What do the enzymes superoxide dismutase, catalase and peroxidase all play a role in?

A

Scavenging for free radicals

39
Q

Name two fat-soluble antioxidants.

A

Tocopherols, Carotenoids

40
Q

Name one water-soluble antioxidant.

A

Ascorbic acid

41
Q

Describe the relationship between certain antioxidants and glaucoma.

A

Carotenoid-rich foods (oranges, collard greens) reduce the risk of glaucoma.

42
Q

What are the physiological consequences of a Vitamin E definciency?

A

Hemolysis and RBC sensitivity to oxidative damage

43
Q

What disease can result from Vitamin E deficiency?

A

hemolytic anemia

44
Q

Who is most at risk for Vitamin E deficiency?

A

A smoker, because they generate more oxidative stress

BIBC120 (21 decks)

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