Flashcards in Fat Soluble Vits Deck (11):
Fat soluble vitamins are isoprenoids (repeats of isopentyl pyrophosphate). Building blocks for cholesterol. Fat malabsorption can lead to fat soluble vitamin problems. Fats are transported from intestines by chylomicrons.
Three forms = Retinal, Retinol, Retinoic Acid
Commonly found as retinol ester in animals and retinal in plants. Beta Carotene is oxygenated and cleaved into two retinals which are then converted into retinols
Transported by chylomicrons and retinol binding protein (instead of VLDL)
prosthetic group of rhodopsins. Retina uses it to sense light, upon light absorb it switches from cis to trans. Change in the way the molecule sits in the membrane is detected by opsin. This sends an action potential to brain.
Def = night blindness
acts as steroid hormone, essential for maintenance of epithelia and membranes, not directly involved in vision.
Deficiency = metaplasia (change in type of epithelia) from columnar to keratinized squamous epithelia cells. Essentially wet to dry. This leads to blindness.
Toxicity high lvls of Retinoic acid can be teratogenic
UVB is required to open up chol ring in the skin to form cholecaleiferol (D3). D3 goes to liver and then to kindey where it meets with PTH and gets converted to calcitrol (active vit D).
This is the only pathway where reg is by final step, calcium lvls. Calcitrol works together with PTH to increase plasma Ca lvls. can be used as osteoperosis treatment
Vit D Def
Bone mass loss, Ricketts in youth, osteomalacia in old
Vit D Tox
Hypercalcemia, hypercalcuria, metastatic calcification, renal and CV dmg
Alpha tocopherol family, believed to be an antioxidant. may be useful against oxidation of LDL to foam cells in artherosclerosis
Inhibits platelet aggregation
Vit E Def
Mild hemolytic anemia
coagulation vitamin, used for clotting. First fat soluble vitamin to be def in fat malabsorb
Inhibited by warfarin