Human Body Synthesis Essay

The human body has evolved throughout time, adapting to the environment that they live in. The sun is part of the environment that everyone and anything is exposed to everyday, but the sun produces ultraviolet radiations that can damage the human skin and lead to skin cancer. Ultraviolet radiation is composed of three types of rays; ultraviolet A, ultraviolet B, and ultraviolet C. Ultraviolet C is the most dangerous type of radiation, but does not penetrate the earth’s ozone layer unlike ultraviolet A and B (Medicinenet, 2013). Ultraviolet A stimulates melanin pigmentation, as it is able to reach deep into the dermis. Ultraviolet B is mainly absorbed by the epidermis and upper dermis, and is also responsible for pre-vitamin D3 production in the skin as well as stimulating the production of melanin like ultraviolet A. With continuous exposure to ultraviolet radiation, there is a higher chance of DNA damage (Costin and Hearing, 2007). In order to protect the skin, the human body has adapted to the radiation through tanning. …show more content…
Tanning is composed of two phases; immediate tanning and delayed tanning. Immediate tanning is a quick response to ultraviolet A or visible light, that produces a transient brownish tan. Immediate tanning begins immediately after exposure, reaching a maximum within one to two hours. It will then fade between three to twenty-four hours after exposure (Costin and Hearing, 2007). Immediate tanning starts as a greyish coloration that gradually fades to a brown pigmentation over a period of minutes to days. The response depends on the amount of exposure to radiation as well as skin type. The response is cause by the oxidation of pre-existing melanin and redistribution of melanosomes. Depending on skin type, the visibility of the tan can be almost unnoticeable in fair skin types whereas darker skin types, types IV-VI, it is easily noticeable (Agar and Young,