skin cells and their allies hair sweat and oil glands form a first line of defense from the environment and two important cell types coratina sites and melanocytes
the correctness sites are the cells that form the surface of the skin and are on the frontline for taking insults from the environment deeper down in the epidermis right at the base of the layer we find the melanocytes these star shaped cells produce the important
pigment melanin
let's zoom inside a molana site to see how this works melanin is produced inside what looked like spheres throughout the melanocyte these are the melanosomes chemical reactions inside melanosomes turn the amino acid tyrosine into melanin the proportion of two main forms of melanin produced a reddish yellow type versus a black brown type the total amount of melanin in each melanosome and the number of melanosomes in the epidermis all vary from person to person and determine their skin color melanosomes are the melanin factories inside melanocytes
but for melanin to do its job melanosomes need to be transported to the keratinocytes via the
melanocytes long projections inside the keratinocytes some melanosomes form a cap around the cell nucleus the melanin inside the melanosomes absorbs the ultraviolet energy from sunlight reducing the amount of ultraviolet radiation that reaches the nucleus and in particular the DNA inside the nucleus
ultraviolet radiation can cause mutations in DNA that can lead to cancer when ultraviolet radiation increases melanin
production increases and more melanosomes are delivered to karatina sites most people can adjust to greater exposure to the sun by turning up melanin production and tanning but their genetic inheritance determines both the baseline color of their skin and how much it can tan
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