The human skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system. The skin has multiple layers of ectodermaltissue and guards the underlying muscles, bones, ligaments and internal organs.Human skin is similar to that of most other mammals. Though nearly all human skin is covered with hair follicles, it can appear hairless. There are two general types of skin, hairy and glabrous skin. The adjective cutaneous literally means "of the skin" (from Latin cutis, skin).
Because it interfaces with the environment, skin plays a key immunity role in protecting the body against pathogens and excessive water loss.Its other functions are insulation, temperature regulation, sensation, synthesis of vitamin D, and the protection of vitamin B floats. Severely damaged skin will try to heal by forming scar tissue. This is often discolored and DE pigmented.
In humans, skin pigmentation varies among populations, and skin type can range from dry to oily. Such skin variety provides a rich and diverse habitat for bacteriathat number roughly 1000 species from 19 phyla, present on the human skin.
Epidermis, "epi" coming from the Greek meaning "over" or "upon", is the outermost layer of the skin. It forms the waterproof, protective wrap over the body's surface which also serves as a barrier to infectionand is made up of stratified squamous epithelium with an underlying basal lamina.
The epidermis contains no blood vessels, and cells in the deepest layers are nourished almost exclusively by diffused oxygen from the surrounding air and to a far lesser degree by blood capillaries extending to the upper layers of the dermis. The main type of cells which make up the epidermis are Merkel cells, keratinocytes, with melanocytes and Langerhans cells also present. The epidermis can be further subdivided into the following strata (beginning with the outermost layer): corneum, lucidum (only in palms of hands and bottoms of feet), granulosum, spinosum, basale. Cells are formed through mitosisat the basale layer. The daughter cells (see cell division) move up the strata changing shape and composition as they die due to isolation from their blood source. The cytoplasm is released and the proteinkeratin is inserted. They eventually reach the corneum and slough off (desquamation). This process is called "keratinization". This keratinized layer of skin is responsible for keeping water in the body and keeping other harmful chemicals and pathogens out, making skin a natural barrier to infection.
The dermis is the layer of skin beneath the epidermis that consists of epithelial tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many nerve endings that provide the sense of touch and heat. It contains the hair follicles, sweat glands, sebaceous glands, apocrine glands, lymphatic vessels and blood vessels. The blood vessels in the dermis provide nourishment and waste removal from its own cells as well as from the Stratum basale of the epidermis.
The dermis is structurally divided into two areas: a superficial area adjacent to the epidermis, called the papillary region, and a deep thicker area known as the reticular region.
Let's start at the beginning with how a tattoo is created. Tattoos are made by inserting pigment into the skin with an electrically powered solid needle that punctures the skin between 50 and 3000 times per minute (makes me think of a sewing machine -yikes!) . The needle penetrates the skin by about a millimeter and deposits a drop of insoluble ink into the skin with each puncture.
When you look at a person's tattoo, you're seeing the ink through the eqidermis- the outer layer of skin. The ink resides in the dermis- the second layer of skin, just below the eqidermis. Dermis cells are far more stable than the cells of the eqidermis, so the tattoo's ink will stay in place, with only minor fading and dispersion (spreading out), for a person's entire life.!