2 things responsible for skin color include tyrosinase activity and lysosome activity. If you have high tyrosinase activity that means you make a lot of melanin and your skin has darker pigmentation. If low activity you have lighter skin. What breaks down melanin is fusing lysosome with melanosome all the lysosomal enzymes degrade melanin. People have certain lysosomal activity rates. If they are very active you are fair skinned individual if they are not active you are darker skin. If somebody loses tan fast than there lysosomal activity is fast. There can be a reddish tint of skin due to oxyhemoglobin ( blood that has 02 in it) if arteries are dilated meaning they are close to surface of skin that reddish color can give you a reddish tint to skin. We know sites of inflammation look red. You can get a bluish tint due to deoxyhemoglobin in veins, this could indicate poor circulation to an area also due to cold temperatures is cyanosis. If temperatures are cold body has a tendancy to make diameter of blood vessels smaller bringing blood closer to center of body. If hot outside we dilate our blood vessels. If circulation is bad or is cold out, get a bluish tint to surface of skin. Can have a yellowish tint to skin and possible eyes if you have jaundice. Jaundice is a build up of certain molecule in the interstitial fluid. When you break down a red blood cell you need to get rid of the hem group of a RBC and if can’t get rid of you have a build up of bi product in the interstitial fluid. Vitamin D3 production happens when keratinocytes in the basale and spinosum convert cholesterol into a derivative (VD). Name for vitamin D is called cholecalciferol. In the skin we take cholesterol and an enzyme converts cholesterol into VD3. Vitamin D3 is a steroid hormone, but we consider a vitamin because it is essential for the absorption of calcium and phosphate in our body. The enzyme for VD3 production is also UV activated, whatever enzyme is. The liver will convert this cholecalciferol into an intermediate that the kidneys will use. Your skin has enzyme that converts cholesterol to vitamin D…vitamin d will go to liver and liver will convert to intermediate that intermediate will go to kidneys and kidneys convert to calcitriol. Calcitriol is a hormone that is facilitating the absorption of calcium in your small intestine. Not only is it facilitating, but you are not absorbing calcium properly unless you have calcitriol and you don’t have calcitriol unless you have vitamin D flat out. Now if you don’t have calcium getting into your body which you’re not going to if you don’t’ have vitamin d because you don’t have calcitriol. Calcium is one of the major constituents of the inorganic component of bone; bone will be brittle and not very dense.
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