Final Prep Flashcards
vitamins
organic compounds that are vital to life and indispensable to body functions but are needed only in minute amounts; noncaloric essential nutrients.
the fat soluble vitamins
Vitamin A, Vitamin D, Vitamin E, Vitamin K
the water soluble vitamins
B vitamins, Thiamin (B1), Riboflavin (B2), Niacin (B3), Folate, Vitamin B12, Vitamin B6, Biotin, Pantothenic acid, Vitamin C
precursors
provitamins compounds that can be converted into active vitamins.
beta-carotene
an orange pigment with antioxidant activity; a vitamin A precursor made by plants and stored in human fat tissue.
retinol
one of the active forms of vitamin A made from beta-carotene in animal and human bodies; an antioxidant nutrient. Other active forms are retinal and retinoic acid.
rhodopsin
the light-sensitive pigment of the cells in the retina; it contains vitamin A (rod refers to the rod-shaped cells; opsin means “visual protein”).
night blindness
slow recovery of vision after exposure to flashes of bright light at night; an early symptom of vitamin A deficiency.
epithelial tissue
the layers of the body that serve as selective barriers to environmental factors. Examples are the cornea, the skin, the respiratory tract lining, and the lining of the digestive tract.
cell differentiation
the process by which immature cells are stimulated to mature and gain the ability to perform functions characteristic of their cell type.
carotenoid
a member of a group of pigments in foods that range in colour from light yellow to reddish orange and are chemical relatives of beta-carotene, many with a degree of vitamin A activity in the body
retinol activity equivalents
a new measure of the vitamin A activity of beta-carotene and other vitamin A precursors that reflects the amount of retinol that the body will derive from a food containing vitamin A precursor compounds.
vitamin a functions
Vision; maintenance of cornea, epithelial cells, mucous membranes, skin; bone and tooth growth; regulation of gene expression; reproduction; immunity
vitamin d functions
Mineralization of bones and teeth (raises blood calcium and phosphorus by increasing absorption from digestive tract, withdrawing calcium from bones, stimulating retention by kidneys)
vitamin c functions
Collagen synthesis (strengthens blood vessel walls, forms scar tissue, provides matrix for bone growth), antioxidant, restores vitamin E to active form, supports immune system, boosts iron absorption
vitamin b functions
act as coenzymes that serve as helpers to the enzymes involved in the metabolism of food.
help cells to multiply (e.g., red blood cells and cells of the digestive and nervous systems).
are usually consumed in adequate amounts. Folate and vitamin B12 tend to be the B vitamins that are sometimes inadequate in Canadian diets.
are widely distributed in all food groups, except vitamin B12 that is found only in food of animal origin.
tend to be concentrated in the outer coating of grains; milling therefore causes a major loss.
are water soluble, are not stored in the body to any appreciable extent (except B12), are relatively non-toxic, and are excreted in the urine when consumed in excess.
folate functions
a part of coenzymes needed for new cell synthesis
collagen
the chief protein of most connective tissues, including scars, ligaments, and tendons, and the underlying matrix on which bones and teeth are built.
prooxidant
a compound that triggers reactions involving oxygen
coenzyme
a small molecule that works with an enzyme to promote the enzyme’s activity. Many coenzymes have B vitamins as part of their structure (co means “with”).
active forms of five of the B vitamins
thiamin, riboflavin, niacin, pantothenic acid, and biotin—participate in the release of energy from carbohydrate, fat, and protein.
Thiamin
a B vitamin involved in the body’s use of fuels.
beriberi
the thiamin-deficiency disease; characterized by loss of sensation in the hands and feet, muscular weakness, advancing paralysis, and abnormal heart action.
riboflavin
a B vitamin active in the body’s energy-releasing mechanisms.
niacin
a B vitamin needed in energy metabolism. Niacin can be eaten preformed or can be made in the body from tryptophan, one of the amino acids. Other forms of niacin are nicotinic acid, niacinamide, and nicotinamide.
Pellagra
the niacin-deficiency disease (pellis means “skin”; agra means “rough”). Symptoms include the “4 Ds”: diarrhea, dermatitis, dementia, and death.
folate
a B vitamin that acts as part of a coenzyme important in the manufacture of new cells. The form added to foods and supplements is folic acid.
b12
a B vitamin that helps convert folate to its active form and also helps maintain the sheath around nerve cells. Vitamin B12’s scientific name, not often used, is cyanocobalamin.
sources of vitamin a
Retinoyl: fortified milk, cheese, cream, butter, fortified margarine, eggs, liver
sources of beta-carotene
spinach and other dark, leafy greens; broccoli; deep orange fruit (apricots, cantaloupe) and vegetables (winter squash, carrots, sweet potatoes, pumpkin
sources of vitamin c
Citrus fruit, cabbage-type vegetables, dark green vegetables, cantaloupe, strawberries, peppers, lettuce, tomatoes, potatoes, papayas, mangoes
sources of vitamin d
Self-synthesis with sunlight; fortified milk, margarine, and yogurt; liver; sardines; salmon; shrimp
sources of folate
Asparagus, avocado, leafy green vegetables, beets, legumes, seeds, liver, enriched breads, cereal, pasta, grains