Flashcards in 55-NUTRITION – Dr. Groseclose Deck (39):
What is pellagra? What are the “4 D’s” that characterize it?
Pellagra is a deficiency of niacin; “raw skin.” The 4 Ds are dementia, diarrhea, dermatitis and death.
Name the fat-soluble vitamins.
Vitamins A, D, E and K are the fat-soluble vitamins.
In addition to solubility, name 3 ways in which the fat-soluble vitamins differ from the water-soluble ones.
Fat-soluble vitamins accumulate in liver and adipose tissue and may be toxic with excessive accumulation. Water-soluble vitamins are not stored in large quantities and are not readily toxic.
Name 2 pathways for which thiamin is a cofactor.
Thiamin is a cofactor for the Krebs Cycle (Citric Acid Cycle) and for the Pentose Phosphate pathway.
Beriberi – 1o thiamine (B1) deficiency that is rarely seen today.
Pernicious anemia – vitamin B12 deficiency because no intrinsic factor by stomach lining. (B12 poorly absorbed)
Vitamers – structurally related form of a vitamin.
Scurvy – Vitamin C deficiency; fragile capillaries, swollen and bleeding gums, slow wound healing.
Barlow’s disease – infantile scurvy.
Nyctalopia – nightblindness due to vitamin A deficiency.
Xerophthalmia – dry eyes due to vitamin A deficiency.
Kwashiorkor – protein energy malnutrition(PEM); edema, fatty liver, decreased immune fxn
Marasmus – deficiency of protein and total calories; stunted growth, long-term mental and physical defects.
Complete protein – contain correct ratio of a.a. for normal growth and development.
Glycemic index – blood glucose response from food/response from glucose X 100%
What is the biochemical role of niacin? What amino acid is a precursor of niacin in vivo? What vitamins are necessary for the conversion of trp to niacin?
Niacin is the active site of NADP (used for redox reactions). Tryptophan is a precursor of niacin. Pyridoxal and riboflavin are necessary for the conversion.
Name 2 enzymes that require a riboflavin-containing cofactor?
Succinic dehydrogenase, monoamine oxidase and glutathione reductase require a riboflavin cofactor.
What are the 2 major biochemical roles for pantothenate?
Pantothenate is a structural component of coenzyme A and of acyl carrier protein. It is involved in oxidation of acetate and fatty acids and in the synthesis of fatty acids, steroids, acetyl choline, and porphyrins.
For what class of reactions is biotin a cofactor?
What is avidin? In what natural product is it found?
Avidin is a protein in raw egg whites.
Gaston! (beauty and the beast)
What is the most common sign of folate deficiency?
What is the biochemical role of folate?
Folate is a carrier of one-C fragments for the synthesis of purines, thymidine and methionine and for the metabolism of serine and histidine. Folate is the central molecule in one-carbon metabolism.
What are the other names for B12? What metal does it contain?
Cobalamin and cyanocobalamin.
Name 3 causes of secondary B12 deficiency?
Failure of the stomach lining to produce intrinsic factor (pernicious anemia)
What are the biological roles of B6?
Vitamin B6 (pyridoxal)
- Carry C groups during transamination and - decarboxylation reactions
Generate niacin from Trp
Metabolism of other AAs
Synthesize porphyrins (5-Ala synthetase)
Breakdown glycogen (glycogen phosphorylase)
What is the chemical name of vitamin E?
What is the biological role of vitamin K? How is it related to the metabolism of Ca2+?
Vitamin K is needed for coagulation. It is also a cofactor for the gamma carboxylation of glucine groups. It is also a cofactor for the synthesis of Ca2+ binding protein of the kidney, bone and placenta.
Explain why “vitamin D” is not really a vitamin. How is 1,25-dihydroxycholecalciferol synthesized in the body?
Vitamin D can be synthesized by the skin with sunlight. Enzymes in the liver and kidney generate 1,25-dihydroxycholecalciferol from vitamin D in response to PTH.
What is the normal range of concentration of plasma calcium?
How is plasma calcium controlled? (PTH, kidney, vitamin D, etc)
Plasma calcium is controlled by bone remodeling. PTH is able to breakdown bone to raise plasma Ca2+ levels, calcitonin (from the kidney) is able to decrease its secretion from urine and calcitriol is able to absorb Ca2+ from the gut with the help of vitamin D.
What other major mineral is controlled with calcium?
What are the biochemical roles of Mg2+?
Used for structural components and wherever ATP participates in a reaction.
Name 1 or 2 enzymes for which each of the following minerals is a cofactor: molybdenum, selenium, manganese, zinc.
Molybdenum – xanthine oxidase
Selenium – glutathione peroxidase
Manganese – mitochondrial superoxide dismutase
Zinc – lactate dehydrogenase and carbonic anhydrase
With what general biochemical process is chromium associated?
Chromium is associated with the normal action of insulin.
What is the biological role of I? What is a goiter?
I is needed for normal growth and development as part of the thyroid hormone. A goiter is an enlarged thyroid gland because of iodine deficiency.
What is the biological role of fluorine?
Fluorine strengthens bones and teeth.
What are the signs and symptoms of Zn deficiency?
Zinc deficiency shows slow wound healing and diminished smell and taste.
Explain the concept of “sparing” with respect to vitamin nutriture.
Absorption vs. mobilization of vitamin. It is possible to have adequate of a nutrient but still not have adequate nutriture.
What information do the Harris-Benedict equations yield? What are the variables of those equations?
The equations tell you your RMR (resting metabolic rate) which is your caloric requirement. The variables are gender, age, weight and height.
What happens to the protein ingested in excess of that required?
Broken down and stored.
What is the equation relating Joules and calories?
1 calorie = 4.2 Joules
Name as many roles of dietary fiber as you can.
Dietary fiber provides bulk in the diet and keeps the food bolus hydrated by binding H2O (which keeps the stool soft). They have also been implicated in lowering plasma cholesterol and preventing colon cancer.
Why is the recommended lower level of dietary cholesterol at zero? (isn’t cholesterol an essential constituent of membranes?)
Our body has the ability to make cholesterol on its own with out consuming it.
What are the recommended proportions of dietary carbohydrate, fat and protein?
Protein 30-40g/day (10-15% of daily calorie content). Fat should be 15-30% of daily calorie content and carbohydrate the rest (typical Western diet = 46% carbohydrates).
Why is choline considered in the secretion on dietary fats, though it is not itself a fat?
Choline occurs in the diet in the lipid lecithin (part of egg yolk).
What are the effects of dietary fatty acids on plasma cholesterol?
Saturated fatty acids increase plasma cholesterol by much more than a high cholesterol diet alone. Monosaturated fatty acids have no effect on plasma cholesterol, whereas polyunsaturated fatty acids may lower plasma cholesterol.
What is the biological role of Vitamin C?
Vitamin C (ascorbate)
- Proper synthesis of collagen
- C-terminal amidation of neuropeptides
- Fxn of dopamine b hydroxylase
- Reducing agent
- Antioxidant in vivo (sparing effect on vitamins A and E)
Name 4 processes in which vitamin A plays a role. What is a major source of this vitamin synthesized by plants?
2. differentiation of epithelial cells
3. maturation of cartilage into bone
4. proper maturation and maintenance of the reproductive system.
Vitamin comes from green and yellow vegetables like carrots (carotene), liver and dairy products.