Vitamin D Flashcards
it is called the the “Sunshine vitamin” which acts as a steroid hormone; Anti-rachitic or ricket preventive vitamin
Vitamin D
Other name for vitamin D
(Calciferol)
Precursors of VIt D in plants
Ergosterol
Precursors of VIt D in animals
7-dehydrocholesterol
Sources of vit D
fish liver oils (sardines, salmon and herring)
Poor sources of vit D
Human milk and unfortified cow’s milk
inactive form of vitamin D in the skin
7-dehydrocholesterol
predominant in circulating metabolite;
product of vit D hydroxylation in the liver.
25-hydroxyvitamin D3 or calcidiol
most active/Potent form of vitamin D
1,25 dihydroxyvitamin D3 or calcitriol
hormones that activates vitamin D
Parathyroid hormone
Upon UV exposure of ergosterol it turns into _____
Ergocalciferol
Upon hydroxylation of 7-dehydrocholesterol it turns into ______
Cholecalciferol
Ca binding protein
Calbindin
Functions of Vitamin D:
- Facilitates the absorption of calcium during low dietary calcium intake
- Maintenance of calcium and phosphorus homeostasis
- cell differentiation/cell proliferation
acts as a hormone binding VDR (vit D receptor proteins) in the nucleusregulates gene expression
Calcitriol
Vitamin D Deficiency : a syndrome (abnormal muscle twitching, cramps, spasms in the wrists and joints)
Tetany
Vitamin D Deficiency in children
RICKETS
Vitamin D Deficiency in Adults
OSTEOMALACIA
A disease involving impaired mineralization of the bone
bone pain, muscular tenderness, hypocalcemic tetany
enlargement of the epiphyses of the long bone and rib cage, bowing of the legs, bending of the spine and weak and toneless muscles
Rickets
Knock knees
Rachitic rosary
Vitamin D Toxicity: (more than 25 μg/day (infants & small children) and 50 μg/day (adults)
◦elevated serum calcium and phosphorus, calcinosis of kidney, lungs, ear
Hypervitaminosis D
Signs of Excessive Vitamin D Toxicity
Excessive calcification of bone
Kidney stones
Hypercalcemia
Headache
Signs of Excessive Vitamin D Toxicity
Weakness Nausea and vomiting Constipation Polyuria Polydipsia/extreme thirstiness
