Final - Lecture 10 Flashcards
(44 cards)
Define ‘Vitamins’
Essential organic substances needed in trace quantities for normal growth, metabolism and function
Do vitamins directly yield energy?
No, but they facilitate energy-yielding processes.
What three physiological aspects are affected by vitamins?
metabolism, development and immunity
Vitamins are not inorganic nutrients. What are inorganic nutrients called?
Minerals.
What are the two classes of vitamins?
1) Water-soluble
2) Fat-soluble
How do the two classes of vitamins differ?
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)
Which class of vitamins more easily reaches levels of toxicity?
Fat-soluble
What happens to fat-soluble vitamin intake when lipid absorption in the small intestine is impaired by weight loss medicine?
The uptake is decreased.
What are the three key retinoids?
Retinol (Most abundant) CH2(OH) ^Dehydrogenase Retinal CHO (double bond on O) ^Dehydrogenase Retinoic Acid COOH (C=O and OH)
What foods contain B-carotene, a carotenoid, in high quantities?
Fruits, Veggies (particularly carrots and yams) and leafy greens (dandelion leaves)
B-carotene can produce 2 of which retinoid?
Retinal
Name 3 of the 4 major functions of retinoic acids.
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)
What do children with low vitamin A often experience?
Diarrhea as a result of gut immunity.
Acetaldehyde, an intermediate in the metabolism of alcohol, inhibits the function of what retinoid-associated enzyme?
Retinal dehydrogenase; reduces retinoic acid production
Name the 5 deficiency symptoms of Vitamin A.
(1) Night blindness, (2) Keratinization of epithelial tissue, (3) Xerophthalmia, (4) Infections, (5) Blindness
Describe the xerophthalmia condition.
Loss of mucus leads to dry eyes, and cornea sloughs off
How does a deficiency in vitamin A affect infections?
Immunity is impaired, esp. in the GI tract.
Describe keratinization of the epithelial tissue.
The skin becomes very rough because hair follicles make too much keratin. (Hyperkeratosis)
What are some good sources of vitamin A?
Carrots, sweet potatoes and beef liver
What animal vitamin has the greatest risk of toxicity? What is the UL? What are the symptoms of toxicity?
Vitamin A; 3000 micrograms RAE/day from animal sources; nausea, headache, dizziness, liver damage, hair and bone loss, birth defects and spontaneous abortion (teratogens)
Vitamin A-based medicines typically contain Isotretinoin (Accutane) 13-cis-retinoic acid. How does this differ from retinoic acid?
the C=C connected to COOH is cis. Isotretinoin is widely used in treatment of severe acne, but is also highly teratogenic.
How is consumption of fruits and veggies rich in B-carotene associated with lung cancer?
Sufficient consumption is correlated with reduced risk of lung cancer.
How is consumption of B-carotene supplements associated with lung cancer in high risk groups (smokers)?
Higher rates of cancer was observed in high risk groups as compared to placebo groups.
Synthesis of Vitamin D3 occurs in what parts of the body (In order)? Where is the active form produced?
Skin (UV step), liver, kidney; kidney (calcitrol)
