Chapter 10 Flashcards
What are the two types of vitamins?
water soluble (precursors for coenzymes) and lipid soluble
What is the enzyme, pathway and deficiency of Biotin?
coenzyme=biotin-lysine
main pathway it activates: carboxylation
**alopecia
What is the enzyme, pathway and deficiency of thiamine (B1)?
coenzyme=thiamine PP
main action: decarboxylation
ophthalamoplegia: eyes can’t follow beam of light
Dry beri-beri: polyneuritis; occurs first, neurologic problems
What is the enzyme, pathway and deficiency of niacin (B3)?
coenzyme: NAD(H), NADP(H)
main action: oxidation/reduction
pellagra: nutritional problem
Tryptophan–>niacin
What is the enzyme, pathway and deficiency of folic acid?
coenzyme: THF (tetrahydrofolate)
main action: 1 carbon carrier; donor
megaloblastic anemia: large nucleated red cells in the marrow
What is the enzyme, pathway and deficiency of cyanocobalamin (B12)?
coenzyme: methyl-cobalamin and deoxyadenosyl-cobalamin
pathway: VOMIT
**megaloblastic anemia
What is the enzyme, pathway and deficiency of pyridoxine (B6)?
coenzyme: pyridoxal P (PLP)
main action: transamination
delta aminolevulinate synthase: need b6 (no poryphin so heme not made properly)
isoniazid therapy: treat Tb; binds B6 so can’t be absorbed
sideroblatsic anemiaa: Fe stays in the mitochondria becuase heme not formed properly
Heme: red because porphyrin
What is the enzyme, pathway and deficiency of riboflavin (B2)
coenzyme: FAD(H2)
–when it absorbs light, it degrades; consider with children using phototherapy
main action: oxidation/reduction
**cheilosis or stomatosis
What is the enzyme, pathway and deficiency of ascorbate (C)?
only water soluble vitamin without coenzyme
main action: antioxidant**scurby: ecchymoses, hyperelastic skin, loose teeth
What is the enzyme, pathway and deficiency of pantothenic acid
coenzyme: CoA
main action: carrier of fatty acid, HMG, acetate
Describe scurvy in an infant.
Swelling, bruising
2-10 months old
bottle fed with formula that is overheated for pasteurization and not supplemented with Vitamin C
–Vitamin C is destroyed by excessie heat
gum bleeding doesn’t occur unless erupted teeth
vitamin C: cofactor for proline and lysine hydroxylases in collagen syntehsis
–vitamin C deficiency–> collagen fibers less stable than normal
What are the other roles of vitamin C?
antioxidant
reducing iron in intestine to enhanble iron absorption
hepatic synthesis of bile acids
What are the four lipid soluble vitamins?
A, D, E, and K
A, D: work through enhancer mechanisms
What are the important functions of vitamin D?
What are the important functions of vitamin A?
What are the important functions of vitamin K?
What are the important functions of vitamin E?
How does vitamin D regulate calcium homeostasis?
hypocalcemia–>PTH release–>bind to receptor on renal proximal tubules–>coupled through cAMP to activate 1 alpha hydroxylase
–enzyme converts vitamin D to 1,25 DHCC (calcitriol)—lipid soluble hormone
–1,25 DHCC acts on duodenal epithelial cells
–intracellular receptor=Zn finger protein
–bind to response elements on enhancer regions of DNA to induce synthesis of Ca binding proteins which stimulate Ca2+ uptake from GI tract
–1,25 DHCC also causes Ca2+ reabsorption in the kidney
–1,25 DHCC mobilizes Ca2+ from the bone when PTH is present
BRINGS CALCIUM LEVELS BACK TO NORMAL
25 hydroxycholecalciferol: storage form of vitamin D
What is the action of calcitonin?
bind to receptors on osteoclasts and prevent demineralization