Melanin–Umbrellas of Our Skin, Part 1
22 A cheerful heart is good medicine, but a crushed spirit dries up the bones [another verse about bones].
Melanin does give us the color in our skin, but it has another very specific function: Protection from the sun’s ultraviolet rays. “A Pocket Guide to the Human Body,” pages 67-69.
Like all good sunshades, the umbrellas in our skin are darkly colored. The dark pigment in our skin, called melanin, is typically black or brown [everyone has melanin]. This protein is produced by special cells, called melanocytes, which are located in the lowest level of our epidermis. They produce the melanin for our skin, in the form of tiny granules called melanosomes.
Then they transfer the granules to certain epidermal cells [stem cells] in the lowest layer of our epidermis, where they block the damaging UV that penetrates our skin. In other words, melanocytes are like pigment factories that ship pigments (melanosomes) to other [stem] cells where the pigment is needed.
The mechanism to transfer the granules is itself amazing. The melanocyte is a highly branched cell with long, slender projections, or processes. The melanocyte makes the melanosomes which then move out to the tips of the cell processes. The epidermal cells then “bite off” the tips of these processes, bringing the granules inside their cell. Once inside, the melanosomes are moved and arranged to form a dark “cap” over the epidermal cell’s nucleus. This pigmented cap serves as a tiny umbrella for the nucleus, specifically blocking the most damaging wavelength of the UV light.
How do the melanocytes know which cells to attach to? How do the cells know what to do with the melanosomes? They were programmed by the Master Designer.
How does melanin determine the color of our skin? We will answer that question tomorrow.
Abba, You formed Adam from the dust, added water and Your breath, and Adam came to life! The instant formation of all of the processes in our bodies and them coming to maturity all at the same time is a miracle! Our skin is a perfect example of irreducible complexity. Do things go wrong with our skin? Sure, but it’s the after-effects of sin in the world. We all die and return to dust. May we “count our days,” Lord, and determine to live for You while on this earth. You will lead us to Your country soon enough–or come again to our country! Either way, so be it (amen)!