Anatomy of the Skin.

The skin is the largest organ on the body and plays part in the Integumentary system which also consists of appendages.  Melanin and pheomelanin are the characteristics that contain the DNA information to decide what skin colour a person is. Melanin is what is present in white people skin and pheomelanin is what is present in black people’s skin. However, looking into research, I found an article (Journal of Investigative Dermatology (1991)) which says:

“There are two types of melanin in mammals, the brownish black eumelanin and the reddish yellow pheomelanin. Eumelanin and pheomelanin are present in human hair and this study was carried out to whether both pigments are also present in human epidermis. Samples of epidermis were obtained from suction blisters raised in the upper arm of 13 Caucasian subjects of skin types I, II, and III and analyzed for both eumelanin and pheomelanin using a procedure involving high-performance liquid chromatography. Eumelanin and pheomelanin were found in all epidermal samples and their relative proportions correlated well with those found in samples of hair taken from the same subjects. The lowest concentrations of eumelanin were found in subjects of skin type I, with higher levels in skin types II and III. The concentrations of pheomelanin were more variable and showed no relationship to skin type. Increases in the concentrations of both pigments occurred following PUVA therapy, but whereas the largest increases in eumelanin were seen in skin types II and III, the increases in pheomelanin showed little relationship to skin type. Unlike eumelanin, epidermal pheomelanin also showed little relationship to induced tanning. The present findings could be particularly significant in view of recent suggestions that pheomelanin, rather than protecting the skin against UV radiation, may actually contribute to UV-induced skin damage.”

This article suggests that there is another characteristic present in the skin; eumelanin. 

 

There are 3 main layers to the skin. There are:

• ·        The Epidermis.

• ·        The Dermis.

• ·        The subcutaneous layer.

The Epidermis.

The epidermis is the top layer of the skin and is sub divided into 5 layers;

• ·        Stratum germinativum. This is the deepest layer and helps the skin regenerate.

• ·        Stratum spinosum. This layer protects against foreign materials.

• ·        Stratum granulosum. It acts as a waterproof barrier.

• ·        Stratum Lucidum. This is only present where the skin is thick and is to help deal with friction.

• ·        Stratum Corneum. This consists of dead cells.

The epidermis has 7 main functions. These are;

·        Sensation- Pressure, pain, temperature, touch.

·        Heat regulation- hairs, sweat, blood capillaries expand.

·        Absorption- moisture, UV rays.

·        Protection- bacteria, the skins acid mantle.

·        Excretion-  to get rid of salt and toxins.

·        Secretion- (because we need it) oil, acid mantle.

·        Production of vitamin D- bones, nails, hair.

The Dermis. (true skin)

This has 2 layers.

·        Papillary layer- bloods vessels

·        Reticular layer- collagen and elastin. 

The dermis is four times thicker than the epidermis.

The structure is made up of;

• ·        Blood and lymph supply

• ·        Lymphatic vessels

• ·        Sebaceous glands

• ·        Arrector Pili Muscle (causes goosebumps)

• ·        Sweat glands/ sudoriferous glands

• ·        Eccrine glands

• ·        apocrine sweat glands
  
  
  The subcutaneous layer.
  This layer consists of fat cells that act as shock absorbers and protect the body from mechanical trauma.