> Structure of the Skin <

The skin covers the entire surface of the human body. In an adult, the skin has a surface area of about 1.8 square meters (20.83 square feet). The skin is sometime called the cutaneous membrane or the integument. Because the skin has several accessory organs, it is also possible to consider it as the integumentary system.

The skin has two regions: the epidermis and the dermis. The epidermis is the outer and thinner region of the skin. It is made up of stratified squamous epithelium divided into several layers; the deepest layer is the stratum basale, and the most superficial layer is the stratum corneum. The cells of the stratum basale lie just above the dermis and are constantly dividing and producing new cells that are pushed to the surface of the epidermis in two to four weeks. As cells are pushed toward the surface of the skin, they become flat and hard, forming the tough, uppermost layer of the epidermis, the stratum corneum. Hardening is caused by keratinization, the cellular production of a fibrous, waterproof layer called keratin.

The dermis is a deeper and thicker region than the epidermis. The dermis is composed of dense irregular connective tissue. The upper layer of the dermis has fingerlike projections called dermal papillae. Dermal papillae project into and anchor the epidermis. In the epidermis dermal papillae cause ridges that we call fingerprints.

The hypodermis lies below the dermis. The hypodermis is composed of loose connective tissue, including fat (adipose) tissue. The fat tissue stores energy that can be used later if needed. Adipose tissue also helps insulate and shape the body.

> Accessory Structures of the skin <

Hair, nails, and glands are structures of epidermal origin, even though some parts of hair and glands are found in the dermis.

Hair is found on all body parts except the palms, soles, lips, nipples, and portions of the external reproductive organs. Most hair is fine and downy, but the hair on the head can range from thin and downy-thick and rough. Hairs come from complex structures called hair follicles. Hair follicles are formed from epidermal cells but are located in the dermis. The follicle cells continually divide, producing new cells that form the hair. The cells are first nourished by dermal blood vessels but as they grow away from the source of nutrients they become keratinized and die.

Nails are found on the frontal part of your fingertip and grow from special epithelial cells at the base of the nail called the nail root. The epithelial cells become keratinized as they grow over the nail bed. Nails ordinarily grow only 1mm./week.

Glands are groups of cells specialized to produce and secrete a substance into ducts. Kinds of glands and their functions can be found at: http://www.reference.com/search?q=glands

> Disorders of the skin <

Skin is very accountable to many disorders, some that are annoying and others that can be life threatening. Though seldom life threatening, skin disorders can be uncomfortable and may cause chronic disabilities. Because the skin is so visible, skin disorders can lead to psychological stress. There are many disorders of the skin that require clinical care by a physician or other healthcare professionals. Some examples of common skin disorders can be found at: http://www.merck.com/mmhe/sec18.html

The process of wound healing:

1. A deep wound ruptures blood vessels, and blood flows out and fills the wound.

2. After a blood clot forms, a protective scab develops. Fibroblasts and white blood cells migrate to the wound site.

3. A new epidermis forms, and fibroblasts promote tissue regeneration.

4. Freshly healed skin.

Burns

1. Rule of nines- a technique that is used for estimating the extent of a burn.

Head and neck-9%

Arms, shoulders, and hands-18%

Perineum-1%

Anterior legs and feet-18%

Posterior legs and feet-18%

Anterior trunk-18%

Posterior trunk and buttocks-18%

2. Types of burns

-First-degree burns, the mildest of the three, are limited to the top layer of skin:

Signs and symptoms: These burns produce redness, pain, and minor swelling. The skin is dry without blisters.

Healing time: Healing time is about 3 to 6 days; the superficial skin layer over the burn may peel off in 1 or 2 days.

-Second-degree burns are more serious and involve the skin layers beneath the top layer:

Signs and symptoms: These burns produce blisters, severe pain, and redness. The blisters sometimes break open and the area is wet looking with a bright pink to cherry red color.

Healing time: Healing time varies depending on the severity of the burn.

-Third and fourth-degree burns are the most serious type of burn and involve all the layers of the skin and underlying tissue:

Signs and symptoms: The surface appears dry and can look waxy white, leathery, brown, or charred. There may be little or no pain or the area may feel numb at first because of nerve damage.

Healing time: Healing time depends on the severity of the burn. Deep second- and third-degree burns (called full-thickness burns) will likely need to be treated with skin grafts, in which healthy skin is taken from another part of the body and surgically placed over the burn wound to help the area heal.

> Effects of Aging <

As we age, the skin becomes thinner. This is because the underlying fat, so abundant at infancy, is slowly lost. The skin’s connective tissue undergoes changes, causing the skin to lose firmness and become dry. The sweat and oil-secreting glands in the skin also decrease, which makes it harder for the skin to hold moisture. The blood vessels naturally become more fragile, so they are more likely to rupture and leak into the skin. For more skin problems that occur with age go to: http://www.medicinenet.com/script/main/art.asp?articlekey=43078

> Functions of the skin <

· The skin has a protective function

· The skin helps regulate temperature and water loss

· The skin produces vitamin D

· The skin gathers sensory information

> Hyperthermia and Hypothermia <

Hyperthermia, a body temperature that is above normal, and hypothermia, a body temperature that is below normal, indicate that the body’s regulatory mechanisms have been overcome. Some examples of hyperthermia and hypothermia are listed below:

· Hyperthermia- heat exhaustion, heat stroke, and fever

· Hypothermia- uncontrollable shivering, incoherent speech, lack of coordination, and shallow breathing

> Upgrades <

· Skin grafting- if your skin is badly damaged skin grafting takes skin from another part of your body and transplants it to the place you need it.

· Face lifts- plastic surgery on the face for elevating sagging tissues and eliminating wrinkles and other signs of age.

> Road side assistance <

· American Cancer Society- http://www.cancer.org/docroot/home/index.asp

· American Skin Association- http://www.americanskin.org

· American Burn Association- http://www.ameriburn.org/