Endocrinology/CaHomeostasis/IntroToVitD

POINT!

Vitamin D may be sourced from the diet or via the conversion of provitamin D in the skin under sunlight.

An Introduction to Vitamin D

Ultraviolet rays convert Provitamin D in Vitamin D in the skin. This Vitamin D enters the circulation where it is taken up in the liver. Another source of Vitamin D is through absorption by the small intestine, this may also be taken up in the liver.

In the liver Vitamin D is hydroxylated. This hydroxylated Vitamin D enters the circulation where it can be further hydroxylated in the kidney to produce Active Vitamin D. This fully active Vitamin D enters the circulation.

Challenge Quiz

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<GIFT> //LEVEL:2 //RAND 1. Which TWO of the following are original sources of Vitamin D? {=skin~kidney~=GI tract~liver}