MCP 5 Flashcards
lipid soluble vitamins
A, D, K, and E. structure resembles lipids. generally are stored more efficiently than water soluble. deficiencies dont arise as quickly. toxicity may be a problem, especially with D and A.
how do vitamin deficiencies arise?
poor nutrition, increased demand, problem with absorption of one or more vitamins, interactions with medications
water soluble vitamins
B and C. more hydrophillic structure. in general, deficiencies can arise more rapidly if vitamin is unavailable since they are excreted efficiently. less likely to be toxic
vitamin A functions
visual cycle: rhodopsin and cone opsins. synth of certain glycoproteins and mucopolysaccharides. retinoic acid: acts as a hormone. antioxidant
vitamin A deficiency
night blindness early, xerophtalmia (thickening of conjunctiva) advanced. follicular hyperkeratosis (goosebumps that dont go away). anemia despite normal iron intake. poor growth in children. increased suceptibility to infection and cancer. susceptible groups are poor, malnourished, and premature babies
vitamin A toxicity
accumulates in liver. excess intake can be toxic. symptoms include nausea, diarrhea, bone pain, scaly skin, and orange cast to skin.
vitamin D functions
maintaining bone. calcium homeostasis. acts as a hormone: receptors are present in many tissues but full range of activity is unknown
vitamin D deficiency
rickets in children, osteomalacia in adults. increased susceptibility to breast and other canceres, metabolic syndrome/diabetes, and infection. susceptible groups are poor, elderly, alcoholics
synth of active vitamin D
needs three organ systems: skin (sunlight), liver, and kidney (both hydroxylation)
active form is called calcitriol
vitamin D and cancer
low serum vitamin D in post menopausal women is correlated with increased risk of breast cancer. polymorphisms of D receptor and breastcancer links have been amde. D effects are postulated to arise from cell cycle signalling effects through the D receptor
vitamin K functions
localization of enzymes required during blood clotting. helps catalyze addition of gamma-carboxyglutamate to clotting enzymes.
vitamin K deficiency
results in easy bruising, bleeding, and hemorrhage. susceptible groups are newborn infants, patients on long term antibiotics, elderly and other with defects in fat absorption. babies lack bacteria that make vitamin K and deficiency can lead to brain bleed. given shot at birth. In adults, long term antibiotics can kill the bacteria that make K.
vitamin K in blood clotting
essential for enzymes involved in GLA modification of several clotting enzymes
vitamin E function
antioxidant. scavenges free radicals. protects membranes from damage. prevents oxidation of LDL
vitamin E deficiency
cardiovascular disease. neurological symptoms. susceptible groups include patients with severe, prolonged defects in absorption (celiac) or genetic effects