L3: vitamins A and K Flashcards
What are the fat soluble vitamins ?
A , D , E , and K
What are some differences between fat and water soluable vitamins ?
fat soluble vitamins are stored mostly in the liver
- and excess is NOT excreted
- manifestation of fat soluble vitamin deficiency is also much slower and takes place after all stores have been depleted .
water soluble vitamins on the other hand are transported freely in the blood and not stored to any great extent ( except vitamin B12)
- manifestation of deficiency is also much quicker
- excess of water soluable vitamins can be excreted so toxicity is not as common
- required frequently in small doses
what are the 3 active forms of vitamin A found in animal tissues ?
collectively known as retinoids :
- retinol
- retinal
- retinoic acid
what is the inactive form of vitamin A in plants ?
Carotenoids ( can be cleaved to form retinol )
what is required for the absorption of Vitamin A and where is it stored?
bile and dietary fat are required for absorption .
vitamin A is then stored in the liver and in adipose tissue
how is vitamin A transported from the liver to other tissues in blood ?
bound to retinol binding protein
what does vitamin A deficiency result in>?
- rough skin
- night blindness
- increased susceptibility to infections
- retarded skeletal growth
vitamin A can cause congenital malformations in the developing fetus.
.
what forms does vitamon K exist in ?
Vitamin K1 (Phylloquinone): found in Green vegetables.
Vitamin K2 (Menaquinone): synthesized by intestinal bacteria.
Vitamin K3 (Menadione): synthetic, water soluble form for therapy (metabolized to phylloquinone).
what is the main metabolic role of vitamin K ?
it acts as a coenzyme for blood coagulation
how do glutamic acid residues of clotting factors (II, VII, IX & X) rely on vitamin K ?
They undergo vitamin K dependant carboxylation and are converted to their active states .
