just vitamin D

What is a big contributor to the formation of vitamin D?

Sun: Sun → 7-dehydrocholesterol → cholecalciferol → liver → 25-hydroxyvitamin D3 → kidney → 1,25-dihydroxyvitamin D3( Metabolic active form of vitamin d circulating in body) NO METABOLIC VITAMIN D IN BODY UNTIL 1,25 DI-HYDROXYVITAMIN D3

What are the two forms of vitamin D?

• Ergocalciferol(D2) → plant form

• Choleciferol (D3) → animal form

What are the most important tissues in vitamin D metabolism?

• Skin, liver, and kidney

What are the functions of vitamin D in the intestine, bone, and kidney?

• Intestine: increases calcium and phosphorus absorption- induces synthesis of calcium binding  protein needed for calcium uptake, as well as stimulates intestinal absorption of magnesium and phosphorus

• Bone: mobilizes calcium storage: binds to receptor→ appears in nuclei of osteoblasts and osteocytes → mobilizes calcium

• Kidney→ calcium conservation , but calcium can also be excreted, also increases phosphorus 

Which animal requires D₃? Which animal does not absorb sunlight?

• Dogs don't synthesize vitamin d on skin (through sun), cats and dogs don't absorb adequate vit D from sunlight

• Poultry require D3 because vit D2=D3 in all other animals

What is caused by vitamin D deficiency?

• Rickets: young animals- soft bones- long bones never grow

• Osteomalacia- older animals- decreased mineral content and softening of bone

• Subclinical signs- lack of bones calcification, ribs and vertebrae fractures first, low plasma calcium phosphorus

 Where is vitamin D stored in the body?

• Stored in liver, three months maximum storage, can be produced by animal but housing conditions and hair coat are complicating factors

Vitamin D is the most toxic vitamin.

yes

Natural source of vitamin D?

• Cod liver, egg yolk, beef liver, cured alfalfa,  uv radiated mushrooms

Symptoms of vitamin d deficiency

• Excess calcium in blood, calcified heart, etc