00:01
Let’s take a look at Vitamin D pathologies.
00:05
Begin by discussion of Vitamin D by looking
at the different ways in which Vitamin D is
provided to us in the active form.
00:14
Vitamin D can be taken up by food; Vitamin
D can come from the skin with the help of
UV light.
00:24
Rarely can Vitamin D deficiency take place
in developed countries through dietary deficiency,
but it could very much occur with lack of
exposure to the sun.
00:37
This then gets into circulation, but this
would be the inactive form.
00:41
The first place that it goes to would be to
the liver and at the site of liver, it gets
25-hydroxylated.
00:49
This is the major circulating type of Vitamin
D, 25-hydroxylated Vitamin D will then turn
down to the kidney.
00:58
Here, with the help of 1-alpha-hydroxylase,
because of PTH working upon it will stimulate
the 1-alpha-hydroxylase resulting in the active
compound of calcitriol or 1,25 dihydroxycholecalciferol.
01:11
The actions of this on the intestine… remember
that Vitamin D is lipid soluble… the lipid
soluble vitamins are ADEK…
A, D, E, K.
01:24
The D, Vitamin D, will pass through the membrane,
act upon the nucleus and so, therefore, bring
about transcription/translation where you
can then reabsorb your calcium from the intestine
and Vitamin D works upon the kidney to reabsorb
both calcium and phosphate whereas PTH only
reabsorbs calcium.
01:47
Production effects of Vitamin D 1,25 dihydroxycholecalciferol
reabsorbs your calcium.
01:54
Unlike PTH, Vitamin D does not promote renal
phosphate wasting.
01:58
In fact, it promotes reabsorption.