Vitamins Flashcards
are a group of chemically unrelated organic molecules that are needed in minute amounts for different physiological functions.
Vitamins
although organic compounds, do not provide energy like other macronutrients and are not used for the synthesis of structural compounds.
Vitamins
This vitamin was discovered by M. Mori in 1922 as a “fat-soluble factor” present in butter and fish oil, and he named it.
Vitamin A
The general term vitamin A includes several related compounds called?
retinol (alcohol), retinal (aldehyde), and retinoic
acid
is required in the diet of all animals.
Vitamin A
Vitamin A in the diet can be provided as a vitamin or through its precursor ? present in plants.
carotenoids
are the plant form of or the precursor of vitamin A
Carotenoids
There are two forms of carotenoids:
carotenes and xanthophylls.
have vitamin A activity.
carotenes (especially β-carotenes)
In the rods of the retina, retinal combines with a protein called
opsin to form?
rhodopsin
rhodopsin also called
visual purple
is light sensitive and enables the eye to adapt to changes in light intensity.
Rhodopsin
is a condition in humans and animals that is caused by vitamin A deficiency; it leads to dryness and irritation of the cornea and conjunctiva of the eye and results in cloudiness and infection.
Xerophthalmia
is also needed for normal skeletal and tooth development and reproductive processes.
Vitamin A
and carotenoids can function as antioxidants thereby protecting cells from oxidative stress and are also involved in modulating cell-mediated and humoral immune responses in animals.
Vitamin A
Upon reaching the microvilli, they are transferred to mucosal
cells, where they are reesterified and are incorporated into the chylomicrons and transported to the lymph for storage
in the liver as
retinyl esters
are split into two within the intestinal mucosal cells to form retinal and are reduced to form retinol.
Carotenoids
As a fat-soluble vitamin, long-term consumption of ? may lead to toxic symptoms
vitamin A
Skeletal abnormalities and thickening of the skin are reported with
hypervitaminosis
includes a group sterol compound that regulates calcium and phosphorus metabolism in the body.
Vitamin D
(vitamin D2, activated plant form)
ergocalciferol
(D3, activated animal form)
cholecalciferol
In the body, vitamin D3 is synthesized from cholesterol when it is converted to ? in the skin upon exposure to ultraviolet irradiation
7-dehydrocholesterol
To become active, it is transported from the skin to the liver, where it is hydroxylated to form?
25-hydroxycholecalciferol
This compound is transported through the blood to the kidneys, where it is further hydroxylated to form?
1,25hydroxycholecalciferol
work in conjunction with vitamin D in blood calcium homeostasis and bone calcification.
parathyroid hormones
are needed for proper absorption of calcium and phosphorus from the gut.
Calcium-binding proteins
A deficiency of vitamin D leads to impaired bone mineralization and abnormal skeletal development and results in a condition called ? in young animals
rickets
A deficiency of vitamin D leads to impaired bone mineralization and abnormal skeletal development and results in a condition called rickets in young animals and ? in growing animals.
osteomalacia
is a term that is used to describe a group of chemically related compounds called tocopherols and tocotrienols
Vitamin E
is the most active biological form of vitamin E and is the one that is added to animal diets
α-tocopherol
The function of ? in the body is to serve as a biological chain-breaking antioxidant and to protect cells and tissues from oxidative damage induced by free radicals and other lipid oxidation products.
vitamin E
prevents the oxidation of lipids by serving as a free radical scavenger and donates electrons from the hydroxyl group of the molecule
Vitamin E
causes damage to unsaturated lipids in cell membranes resulting in the disruption of the structural membrane and cell integrity.
Lipid peroxidation
Vitamin E also has a sparing action on the mineral ?, which is a cofactor for the enzyme glutathione peroxidase, which functions to reduce lipid peroxides.
selenium
Vitamin E deficiency can produce?
white muscle disease, exudative diathesis, and encephalomalacia.
is caused by the degeneration of skeletal and heart muscle fiber, which leads to rapid death due to heart failure.
White muscle disease
in chickens is caused by leaky capillaries in the breast muscle
Exudative diathesis
can only respond to vitamin E treatment.
encephalomalacia (crazy chick disease)
includes a group of compounds called the quinones.
Vitamin K
Vitamin K includes a group of compounds called the
quinones