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Name 3 active forms of Vitamin A and describe functions of each.
- Retinol: Form of vitamin A you get from the diet, supports reproduction (menstrual cycle and sperm development), major transport and storage
- form of the vitamin.
- Retinal: Active in vision, intermediate in the conversion of retinol to retinoic acid.
- Retinoic Acid: Acts like a hormone, regulates cell differentiation, growth (bone elongation), immunity and embryonic development, normal development of
- epithelial linings, cell development (differentiation).
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What are carotenoids?
Pigments commonly found in plants and animals, some of which have vitamin A activity; the carotenoid with the greatest vitamin A activity is beta-carotene.
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What types of cells are affected by vitamin A deficiency?
proteins and epithelial cells.
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Describe the drug Accutane. Why do doctors require female patients to use birth control while taking Accutane?
Accutane is made from retionoic acid; it’s effective against deep lesions of cystic acne.
Itis highly toxic, especially during growth, and has caused birth defects in infants when women have taken it during their pregnancies; that’s why doctors recommend women to use two effective forms of contraception at least once a month after discontinuing its use.
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Describe the various roles of vitamin D in the body.
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Increase/maintain the absorption of calcium
- Regulation of phosphorus
- Immunity
- Prevents cancer tumor growth
- Muscles-Stronger muscles with increased vitamin D
- Reproduction
- Lower blood pressure
- Cellular metabolism
- Blood clotting
- Nerve transmission
- Muscle contraction
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When calcium is adequate in the diet, on which target tissue does active vitamin D act primarily?
Kidneys
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What percent of dietary calcium is absorbed when normal amounts of vitamin D are present in the body?
20-30%
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Under what conditions are longer sun exposures needed for production of vitamin D?
- Dark skin
- Elderly - Can only make ¼ vitamin D compared to when they were younger.
- Latitude - No sun exposure in the north.
- Pollution
- Sunscreen - Anything over 8 SPF will decrease vitamin D synthesis.
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Describe the function of vitamin E in the body.
- Antioxidant
- Stabilize cell membranes
- Regulate oxidation reactions
- Protect polyunsaturated fatty acids and vitamin A
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What are free radicals and how are they formed? What parts / molecules of the cells are vulnerable to damage from free radicals?
Free radicals: Uncharged molcules (typically highly reactive and short lived), having an unpaired valence electron.Phospholipids of the bilayer membrane are damaged by free radicals.
Vitamin E is an antioxidant that neutralizes free radicals and prevents the oxidation of polyunsaturated fatty acids and protects other lipids and related compounds.
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What form of vitamin E is most biologically active in the body?
Alpha-tocopherol
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Which form of vitamin E in supplements is better utilized in the body, natural or synthetic? What is the isomeric form of natural and synthetic alpha tocopherol in supplements?
Natural form (D) of vitamin E is better utilized than synthetic (DL).
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List the best food sources for vitamin E.
- Polyunsaturated plant oils (margarine, salad dressings, shortenings)
- Leafy green vegetables
- Wheat germ
- whole grains, nuts, seeds
- Liver
- fatty meats
- egg yolks, dairy
- Get the majority of Vitamin E from fats and oils
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What drug is enhanced by high intakes of vitamin E. What effect does this have in the body?
- Extremely high doses of vitamin E may interfere with the blood-clotting action of Vitamin K and enhance the effects of drugs used that oppose blood-clotting called anti-coagulants, causing hemorrhage/increase
- bleeding.
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What are the primary functions of vitamin K in the body?
Synthesis of blood-clotting proteins and bone proteins; bone mineralization
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What is osteocalcin and what is its function in bone? How does vitamin K affect osteocalcin?
- Osteocalcin is a protein found in the bone that is secreted solely by osteoblasts and was thought to play a role in the body’s metabolic regulation and is
- pro-osteoblastic (bone-building).
Implicated in bone mineralization and calcium ion homeostasis.Vitamin K and osteocalcin are instrumental to make bones harder.
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What are the major foods and non-food sources of vitamin K?
Food: Liver, leafy green vegetables, cabbage-type vegetables, milk, eggs
Non-food: Bacterial synthesis in the digestive tract (makes 50% of your needs).
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Is vitamin K deficiency common or rare? Under what conditions can vitamin K deficiency occur? What are the symptoms of vitamin K deficiency?
Vitamin K deficiency is rare.
- Secondary deficiency may occur in two circumstances:
- Whenever fat absorption falters, as occurs when bile production fails, vitamin K absorption diminishes.
- Some drugs disrupt vitamin K synthesis and action in the body - antibiotics kill the vitamin K-producing bacteria in the intestine and anti-coagulant drugs interfere with vitamin K metabolism and activity.
Symptoms of vitamin K deficiency: Hemorrhaging.
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Why do infants receive a dose of vitamin K at birth?
- Infants are born with a sterile intestinal tract, and vitamin K-producing bacteria take weeks to establish themselves; and plasma prothrombin is
- low (this reduces the likelihood of fatal blood-clotting during the stress of birth).
Vitamin K is not transferred from the mother to the child.Infants are susceptible to hemorrhaging.
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What effect does high levels of vitamin K have on anticoagulant drugs?
High doses of vitamin K can reduce the effectiveness of anticoagulant drugs used to prevent blood clotting. Increasing vitamin K will increase blood clotting.
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