Vitamin D Flashcards
Who discovered that after destroying the vitamin A content of cod liver oil by oxidation, it still possessed ability to cure rickets?
McCollum
Who received the ultra-violet patent at U.W.
Steenbock
Vitamin D promotes ___ and ___ absorption
Ca and P
-synthesis of a Ca-binding protein
-increase permeability of mucosal cells to Ca and P
Where is and what is Ca and P absorbed as?
in the intestine as vit. D
-25-OH D in the liver
-1,25-(OH)2 in kidney
Vitamin D is thought of as a ______
hormone
Active form is made by the ____
kidney
Active form travels to act on the _____ and ______
bones and intestines
Vitamin D is required for normal ________
calcification
-amount varies with Ca and P amounts and ratio of Ca/P
Highest requirements of vit. D are needed for:
-young and lactating animals
-swine and poultry
-wide Ca and P ratios
What other two hormones are involved in calcification?
-calcitonin (lowers blood Ca levels and puts Ca back into bone)
-PTH (raises blood Ca levels and takes Ca out of bone)
Rickets
disturbance of Ca and P metabolism - poor calcification of bones (occurs in young)
Pigeon-breast
softening of bones in the chest, bowing of the chest
Osteomalacia
failure of the bone matrix to become mineralized
-if mother is deficient possible congenital malformations
-importance of D to adults
Where is vit. D primarily stored?
in liver
-no large transfer to fetus
-not as great ability to store as vit. A
Vitamin D deficiency in chickens
-thin egg shells
-decreased hatchability
-decreased egg production
Parturient paresis (milk fever) in dairy cows
-vitamin D deficiency
-found in lactating cows 1-24 hrs after calving
-drain of blood Ca into milk (plasma Ca declines)
Parturient paresis (milk fever) symptoms
-lack of appetite
-dull and listless
-struggling and unable to stand
-low blood Ca and P
-coma
__________ activates some precursor in the body and certain feeds for vit. D
radiant energy (sunlight)
Ergocalciferol
vitamin D2
Cholecalciferol
vitamin D3
Which forms of vitamin D are effective in mammals?
D2 and D3
Which form of vitamin D is more effective in chicks?
D3 (30x more than D2)
Curative method of vit. D testing quality
“line test” based on the observation of epiphyseal cartilage in rats
Preventative method of vit. D testing quality
% bone ash in chicks
Is there active vitamin D in growing plants?
no
Is there active vitamin D in animals?
yes
-sunlight on skin (predominant provitamin —> active cholecalciferol)
-by eating sources of vit. D
What is the form active in the absorption of Ca in the small intestine?
1,25-(OH)2 cholecalciferol
What food sources are rich in vit. D?
-egg (yolks)
-liver
-fish oils
-fishmeals
-legumes
-leafy alfalfa
Vitamin D is not readily secreted in ____
milk
Radiant energy activates ______
ergosterol (sun curing of roughages)
Is there vit. D in seeds?
practically devoid
Effectiveness of sunlight depends on…
-length and intensity of u.v. rays hitting the body
-confinement
-winter weather
-northern areas
-long haircoat
-aggravated Ca and P ratios
-high concentration rations
Vitamin D toxicity can lead to …
hypervitaminosis which leads to hypercalcemia
Hypercalcemia
Ca deposits in soft tissues, artery walls, etc.
-calcification in pigs if given 1000x the requirement
-humans only about 10x the requirement to be toxic
Excess vitamin D is used in _______ to cause death
rat poisons
