As the interface with the surroundings, it plays the most important role in protecting against pathogens. Its other main functions are insulation and temperature regulation, sensation and vitamin D and B synthesis. Skin is considered one of the most important parts of the body.
In medicine, the branch concerned with the skin is called dermatology.
The skin is often known as "the largest organ of the human body". This applies to exterior surface, as it covers the body, appearing to have the largest surface area of all the organs. Moreover, it applies to weight, as it weighs more than any single internal organ, accounting for about 15 percent of body weight.
Mammalian skin contains, among other things:
- melanocytes (containing melanin, a UV light protective pigment)
- sweat glands
- sebaceous glands
- blood vessels
- nerve endings
Skin is composed of three primary layers: the epidermis, which provides waterproofing and serves as a barrier to infection; the dermis, which serves as a location for the appendages of skin; and the hypodermis (subcutaneous adipose layer), which is called the basement membrane and not actually part of the skin. Much of the hypodermis consists of fat cells, a layer that is very thin in some parts of the body but can also reach considerable thickness in other parts, such as the belly or the buttocks. Below this fat layer are the muscles.
Note that the outer layer of the skin, the epidermis, consists entirely of dead cells.
Skin and spankingEdit
Spanking causes pain by triggering the nociceptors in the skin of the buttocks. The nociceptors are the receptors that cause the perception of pain in response to potentially damaging stimuli: mechanical, thermal, or chemical. In the case of spanking, the stimulus is mechanical.
The buttocks are often bared for a spanking so that the hand (or spanking implement) has direct access to the skin with no layer of clothing between the two. Direct view of the skin also allows to see and feel the physical effects of spanking (redness, warmth, welts and other marks), which is an important means of feedback for the spanker to decide how, where, how long and how hard to spank, and when to stop.
Skin and sexualityEdit
In humans, bare skin, especially that of body parts normally covered, can also function as a strong erotic stimulus — visually and also when being touched, caressed, rubbed, fondled etc. — for both the person giving and the person receiving such attention. See also erogenous zone.