Flashcards in Final - Lecture 10 Deck (44):
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?
What are the two classes of vitamins?
How do the two classes of vitamins differ?
1) Water-soluble vitamins are excreted quicker from the body (storage time of 1-4wks)
2) Fat-soluble vitamins have larger storage pools (months-years)
Which class of vitamins more easily reaches levels of toxicity?
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)
Retinal CHO (double bond on O)
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?
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)
The UV-dependent step of Vitamin D3 synthesis is less efficient in which three groups of people?
Older people, people with dark skin, and people in areas with high smog.
What are the three major functions of Vitamin D?
(1) Calcium homeostasis
(2) hormone effects (differentiation of skin cells)
(3) Inhibition of breast, colon, and prostate cancers. Promotes immunity in general.
Describe Vitamin D's influence on Calcium homeostasis.
Increases Ca absorption in intestine, supports bone growth in youth, promotes release of Ca from bones when Ca is low.
What is the health benefit of vitamin D releasing Ca from bones when Ca is low?
Nerves and muscles need sufficient levels of Ca. Too low results in heart failure.
What are three good sources of vitamin D?
fish, fortified milk, sunlight
Describe the 'Rickets' condition.
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.
What are the consequences of Vitamin D toxicity levels?
Ca becomes depleted in bones and Ca is deposited in soft tissues. This leads to bone malformations, calcification of soft tissues and kidney stones.
What sources produce reactive oxygen species (free radicals)?
respiration, environmental toxins, immune system
What are the beneficial properties of reactive oxygen species?
(1) used by immune system to kill pathogens; (2) used in apoptosis; (3) used for signaling
What are the harmful properties of reactive oxygen species?
(1) produce harmful chain reactions; (2) destroy or modify nucleic acids, proteins and membranes; (3) increased inflammation and risk of cancer and CVD
What reaction does superoxide dismutase catalyze?
2O2 -> H2O2 + O2
What reaction does catalase catalyze?
2H2O2 -> 2H2O + O2
What reaction does peroxidase catalyze?
H2O2 -> 2H2O
What do the enzymes superoxide dismutase, catalase and peroxidase all play a role in?
Scavenging for free radicals
Name two fat-soluble antioxidants.
Name one water-soluble antioxidant.
Describe the relationship between certain antioxidants and glaucoma.
Carotenoid-rich foods (oranges, collard greens) reduce the risk of glaucoma.
What are the physiological consequences of a Vitamin E definciency?
Hemolysis and RBC sensitivity to oxidative damage
What disease can result from Vitamin E deficiency?