Answer:
A. Cholecalciferol, or vitamin D3, is necessary for the normal absorption of calcium and phosphate ions. Vitamin D3 is made by cells in the epidermis due to exposure to sunlight. Without enough exposure to sunlight, the body won't produce enough vitamin D3
Explanation:
Hydroxyapetite is the organic mineral in the bone that maintain the mechanical strengthening of the bone, by interacting with collagen fibres. Calcium and Phosphate ions are the two major components of this bone materials. Generally 90%of bone is calcium , while 80% is phosphate. Phosphate stimulate growth of Oesteocytes. And the latter is important for bone mineralization. Together they maintain bone mineralization and maintenance,thereby preventing bone resorption.
Absorption of Ca and P. into the blood stream to reach the bones cells is conducted by Vit D. Dietary supply is not the only route through which Vit D get to the blood stream. Exposure of the skin to UVB rays of the early morning sunlight is another route.
Vitamin D plays major role in absorption of Ca and P in the body.
Vit. D is naturally synthesized in humans when the skin is exposed to early morning sunlight (UVB). It is usually produce in inactive forms,and undergoes hydroxylation( i.e addition of hydroxyl group -OH) in the liver to be biologically active .
Its active forms acts on the epithelial cells of the intestinal wall to facilitate calcium absorption into the blood stream to reach the bone cells .it also stimulate absorption of Phosphate.
Since these two minerals ensures, mechanical strength, prevention of bone resorption, there availability in the bone must be maintained by Vit, D supply from exposure to sunlight.
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It tends to move away from the area where it is more concentrated. Hope this helps.
Cell, tissue, organ, organ system, organism...................................................................
Answer:
The correct answer is - B) effective pumping of the ventricles ceases because the myocardial cells fail to work as a team, and the brain cannot get adequate oxygen.
Explanation:
When the heart is in an irregular and rapid heart rate due to chaotic electrical signals in the atrial chambers of the heart which leads to a very fast heart rhythm that shows 100 to 175 heart rate. That leads to failure of the myocardial cells that stop the pumping of the ventricles effectively and therefore blood would not reach the brain and the brain would not get an adequate amount of oxygen. This will result in organisms experiencing faint, blackout or stroke-like complications.
