Chapter 7 Flashcards
(17 cards)
Vitamin
must be a vital organic substance that is not a protein, car,b, or fat
- must be necessary to perform its specific metabolic function
- must be able to prevent its associated deficiency disease
- cannot be manufactured by the body in sufficient quantities to sustain life
- considered micronutrients
measured in milligrams or micrograms
Vitamin function
- metabolism: enzymes and coenzymes
- tissue structure and protection: antioxidants
- hormones that affect gene expression
- components of cell membranes
- components of light sensitive rhodopsin molecules in the eyes
scurvy
hemorrhagic disease caused by a lack of Vitamin C
- characterized by diffuse tissue bleeding, painful limbs and joints, thickened bones, and skin discoloration from bleeding
- bones fracture easily, wounds do not heal, gums swell and tend to bleed, teeth loosen
Vitamin types - water soluble
- (Vitamin C and all B)
- easily absorbed by intestinal cells
- move directly into the portal blood circulation
- blood is mostly water, transport does not require assistance from carrier proteins
Vitamin types - fat soluble
- Vitamin A, D, E, K
- absorbed by intestinal cells with fat as a micelle and then incorporate all fat soluble nutrients into chylomicrons
- chylomicrons enter the lymphatic circulation and then the blood
- absorption enhanced by dietary fat
Vitamin types - Phytochemicals
- nonessential organic molecules
- comes from plants
- functions: antioxidant activity, hormonal actions, interactions with enzymes and DNA replication, antibacterial effects
- may protect against cvd, counteract inflammatory compounds, help to prevent cancer, and increase antioxidant status
Vitamin types - supplements
- intended to supplement the diet
- contains 1+ dietary ingredients or their constituents
- intended to be taken by mouth as a pill, capsule, tablet, or liquid
- labeled on the front panel as being a dietary supplement
retinol
chemical name of vitamin A
- name derived from vitamin’s visual functions related to the retina of the eye (back inner lining of the eyeball that catches the light refractions of the lens to form images that are interpreted by the optic nerve and the bran an that makes the necessary light-dark adaptations
carotenoids
organic pigments found in plants
- functions as a scavenger of free radicals, reducing risk of certain types of cancer, prevention of age-related eye disease
- more than 600 identified
- B Carotene most well known
- carotenes - orange pigments that contain no oxygen
- xanthophylls - yellow pigments that contain some oxygen
carotene
group name for three red and yellow pigments (a, b, y) found in dark green and yellow vegetables and fruits
- B-most important to human nutrition because the body can convert it to Vitamin A (making it a primary source of the vitamin)
Vitamin D3 (calciferol)
D3 - cholecalciferol (inactive form)
Vitamin D2 (ergocalciferol)
produced by some organisms upon ultraviolet irradiation from the precursor ergosterol
prohormone
precursor substance the body converts to a hormone
calcitriol
activated hormone form of Vitamin D
- V D2 and D3 must be activated in two successive hydroxylation reactions to yield calcitriol
1-a-hydroxylase
enzyme in the kidneys that catalyzes the hydroxylation reaction of 25-hydroxycholecalciferol (calcidiol) to calcitriol (active form of Vitamin D)
- increased by parathyroid hormone when blood calcium levels are low
resorption
breaking down and releasing of minerals from bones
rickets
disease of childhood characterized by softening of bones from an inadequate intake of vitamin D
- insufficient exposure to sunnligh
- associated with impaired calcium and phosphorus metabolism
