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ANP vitamin k
Test 1
Question | Answer |
---|---|
What is the synthetic, plant, and animal form of vitamin k? | Menadione, phylloquinone, menaquinone |
What pathway should you follow for absorption of vitamin k? | Absorption of lipids. |
What vitamin can interfere with vitamin k absorption? | Vitamin A because it is fat soluble and may have similar transporters |
Phylloquinone's absorption has what kind of transporter and where is it absorbed? | regulated transporter that requires energy, and absorbed in jejunum |
menaquinone and menadione are absorbed where and by what means? | absorbed in the distal small intestines (ileum) and the colon by passive diffusion |
How is vitamin K transported? | mainly in VLDL |
Once absorbed how is phyllaquinone found in the body? | in circulation |
Once absorbed how is menaquinone found in the body? | mainly in the liver: however very little stays in the liver it is in highest concentrations in the adrenal glands, lymph nodes, bone marrow, kidneys and lungs |
Explain in detail the absorption of vitamin K the form of menaquinone | Bile acids breaking fat into micelles, passive diffusion in ileum or colon for menaquinone Packaged into chylomicrons sent to liver as chylomicron remnants, packaged into VLDL's |
Explain in detail the absorption of vitamin K in the form of phylloquinone | Bile acids breaking fat into micelles,absorption via transporters in jejunum for phylloquinone. Packaged into chylomicrons sent to liver as chylomicron remnants, packaged into VLDL's |
Explain in detail the absorption of vitamin K in the form of menadione | Bile acids breaking fat into micelles, passive diffusion in ileum or colon for menadione. Packaged into chylomicrons sent to liver as chylomicron remnants, alkylated (side chains added), packaged into VLDL's |
When is vitamin K done being metabolized and is excreted? | When it is glucuronidated |
How is vitamin k excreted? | conjugated mainly in feces also excreted in urine |
List all the functions of vitamin k in the body | blood clotting, bone mineralization, vascular calcification |
Explain vitamin K's role in blood clotting/coagulation | vitamin k is necessary for the post-translational carboxylation of specific glutamate residues (modified glutamate residues called GLA) which enable protein to bind calcium |
What form must vitamin k be in for activity in the vitamin k cycle to form Gla residues | the reduced hydroquinone form with OH's on it |
Explain the enzyme that helps with post translational carboxylation of glutamate residues | Vitamin K dependent carboxylase enzyme adds a carboxyl group to a glutamic acid residue that attracts and binds calcium really avidly |
Can vitamin K be recycled? | Yes through the activity of the epoxide reductase enzymes |
General features of coagulation cascade | Zymogens converted to enzymes “Complex formation” requiring calcium, phospholipid surface, cofactors Thrombin converts fibrinogen to fibrin monomer Fibrin monomer crosslinked to fibrin Forms "glue" for platelet plug |
Which factors of are vitamin K dependent | II, VII, IX, X |
What are the four components of hemostasis for prevention of blood loss | Vasculature Platelets: ATP, Ca ions(making calcium available at the site of injury) Coagulation proteins/factors Fibrinolytic system |
What starts the coagulation cascade? | Beginning of cascade can be due the presence of collagen, which is normally contained in endothelium |
Explain the importance of calcium in coagulation | The heads of the gla proteins all bind Ca avidly which grabs onto the phospholipid bilayer (because of the charge attraction) and creates a bridge that brings all the clotting factors within proximity of each other |
Who is at risk for vitamin K deficiency | Newborns, malabsorption diseases, liver disease, people who take high doses of vitamin A and E for long periods, injured |
What are some easy assessments of vitamin K deficiency | Blood clotting time longer than normal, plasma prothrombin levels are HIGHLOW? high undercarboxylated osteocalcin |
where is osteocalcin made and by what cells? | bone, osteoblasts |
what is the purpose of osteocalcin? | it inhibits mineralization of bones, |
What would happen if you didn't have Ca present in clotting cascade? | The coagulation factors would not be allowed to assemble in proximity to each other. Calcium is the bridge, without calcium these would never meet, its like match.com |
In the clotting cascade thrombin converts ________ to ______. | fibrinogen to fibrin |
What happens in general following tissue injury? | Vasoconstriction Platelet aggregation fibrin (the glue) formation |
what is fibrin? | fibrin is the end result of the clotting cascade and this protein forms a clot over a wound site |