Vitamin K Flashcards
what are the 4 different types of vitamin K
- phylloquinone K1
- menaquinone K2
- menaquinones MK-4 to MK-6
- menadione K3
bacteria in the colon produce
menaquinones (little absorbed)
the amounts of menaquinones produced in colon are not sufficient for body needs
T
what foods provide the most phylloquinones
broccoli, kale, swiss chard, turnip, watercress, collard greens, spinach, salad greens
how are menaquinones synthesized in the colon
absorbed via passive diffusion (not well due to lack of bile salt emulsification)
what delivers vitamin K to the liver
chylomicron
______ take up phylloquinone and synthesize menaquinone (MK-4)
extrahepatic tissues
principal vitamer in tissues other than the liver
menaquinone -4
are vitamin K levels high or low in the liver
low (less than B12)
what is the vitamin k dependent enzyme responsible for carboxylation
gamma-glutamyl carboxylase
vitamin ___ has the most potent gamma-carboxylation activity (MK-4)
K2
what is required for the protein to become functional and enable it to chelate calcium and interact with other compounds
post-translational carboxylation
found primarily in the liver associated with the RER
gamma-glutamyl carboxylase
4 of 13 blood coagulation proteins require
post translational carboxylation (II (prothrombin),VII, IX, and X)
anticoagulation factors ___, ____, and ___ require post translational carboxylation
C, S, and Z
what are the 4 vitamin K dependent proteins
- osteocalcin (osteoblast)
- matrix Gla protein (mobilization of bone Ca)
- kidney Gla protein (renal reabsorption of Ca)
- growth arrest - specific protein (Gas6)
low intake of vitamin K is associated with
low bone mineral density
women treated with anticoagulants during pregnancy leading to bone abnormalities and impaired neurological development
fetal warfarin syndrome
doses greater than ___ of vitamin e interfere with vitamin k
800IU
deficiency of vitamin k causes
hemorrhagic disorders due to under-carboxylated blood clotting factors inability to bind calcium for thrombin generation
no tolerable upper limit except for
menadione: cause hemolytic anemia and liver damage
