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This video explain why vitamin D is required in Calcium absorption.

Oh salam alaikum wa rahmatullahi water two guys in this lesson we’ll talk about calcium absorption control of vitamin d in calcium absorption calcium is very important in our body because it is needed in the bones it’s needed in the teeth so and also it is needed in the cell for activation of enzymes so calcium is a very important element that’s needed fo in our

Body now to begin with before we took out we talked about calcium absorption we have to know vitamin d because vitamin d is very important in the process of calcium absorption now absorption of vitamin d or prada process of vitamin d or activation of process of vitamin d starts from when vitamin d is absorbed from the diet and absorption of vitamin d from the diet

Is it is mainly absorbed from or it’s mainly gotten from cholesterol cholesterol is converted to 7 d hydro cholesterol and in the presence of uv light it is converted to cholecalciferol precursor of vitamin d3 now this because of vitamin d3 is taken into the liver just from the skin and taken to the liver and in the levite is converted to 25 the hydroxy vitamin

This has another name it is also called calcified eon and from the liver it is taken again to the kidney for further activation and in the kidney it is converted to 125 dai hydroxy vitamin which is also called calcitriol with the help this is very important because for conversion of 25 the head of the i mean to 125 it requires parathyroid hormone so parathyroid

Hormone which is secreted from parathyroid gland is very important for this conversion with the help of the enzyme that is 25 dogs the vitamin d 1 alpha hydroxy less so after this synthesis or after the activation rather the activation of of calcitriol now calcitriol is taken into the intro site for regulation of absorption of calcium now absorption of calcium takes

Place in three steps step number one is entry of calcium into the entry site step number two intracellular regulation of calcium step number three exit of calcium at the basolateral membrane all the three steps are controlled by active form of vitamin d3 which is considered now to understand to understand how these are controlled let us take a look of the intro

Sites at the intestinal lumen now when calcium gets into the cell it is transported by calcium transporter and it binds with calvin and again with calvin it is taken to calcium atpase that is found in the basolateral membrane of the of the cell and calcium is taken from the cell into the blood like that so that’s those are the three steps now how calcitriol how

Does it relate now when calcitriol gets into the cell when calcitriol gets into the cell it binds to vitamin d receptor in the cell and this receptor is a transcription factor it allow calcium to move into the nucleus and when it moved into the nucleus it binds to a specific gene in the dna and this gene will lead to synthesis of a protein through transcription

Translation and this gene and this proteins rather will be expressed on the membrane of the brush border and this protein is called transient receptor potential vanillite which allow more calcium to get into the cell calcitriol also allow the binding of calcium with cal bidden so this binding is important because we don’t want to have intracellular free calcium

That will affect the enzymes that are found within the cell and activating them and affecting this will affect the cell now another important regulation of calcitriol is calcitriol will also help the pumping of calcium from the cell into the blood through the calcium atp’s that is found at the basolateral membrane so because we are pumping calcium from the region

Of low concentration which is inside the cell to extracellular where the calcium is more so to overcome this we need energy and it is an 80 atp dependent and this is with the help of consider calcium is pumped from the cell into the blood vessels so that is how consider regulates

Transcribed from video