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Facts About Your Skin and Skin Cancers

Function of the Skin

Skin Protection from Infectious Agents and Weather Elements

• The skin is a brilliantly designed aspect of the human anatomy structured to prevent loss of essential body fluids, and to protect the body against the entry of toxic environmental chemicals.

Skin Regulates Body Temperature

• The skin is a vital part of the body's temperature regulation system, protecting us against hypothermia and hyperthermia.

• Located in the anterior hypothalamus is a small center that controls body temperature. Heating this area causes vasodilatation of all the skin vessels of the body and sweating.

• Cooling this center causes vasoconstriction of skin vessels and stoppage of sweat secretion. The hypothalamus exerts its controlling effect on the skin vessels through sympathetic nerves. There are also vasoconstrictor reflex centers in the spinal cord.

Skin and the Nervous System

• The skin contains around one million afferent nerve fibers. Most terminate in the face and extremities.

• The brain receives two types of sensations: (1) superficial sensations, including pain, temperature and crude touch, and (2) deep sensations, including sense of position, sense of movement, vibration sense, muscle sense and fine touch.

Structure of Skin

Outer layer –Epidermis

• The stratum corneum with its overlapping cells and intercellular lipid makes diffusion of water into the environment very difficult. Contains sheets of deal cells (corneocytes) that form a protective barrier to germs and weather elements. Proteins called desmosomes are connect the corneocytes that contain inside Natural Moisturizing Factors, which draw moisture into the cell.

• The normal flora of the skin, the fatty acids of sebum and lactic acid of sweat, all are defense mechanisms against invasion by micro-organisms. Langerhans cells present in the epidermis have an antigen-presenting capacity and might play an important role in delayed hypersensitivity reactions.

• Melanin pigment of the skin (living protective cells which contain melanocytes) produces brown pigment to protect us from ultraviolet light

• The stratum corneum also regulates the rate of water loss in skin (Transepidermal Water Loss). Normal skin loses 80-100 grams (about one pint) of water each day. Dry air, soap and washing accelerate this loss of water.

Middle Layer – Dermis

• Contains collagen for a tough and flexible foundation for the epidermis.

• Just one square inch of dermis holds 650 seat glands - Humans have several million eccrine sweat glands distributed over nearly the entire body surface. Each eccrine sweat gland consists of a secretory coil deep in the dermis, and a duct that conveys the secreted sweat to the surface.

• In addition to the secretion of water and electrolytes, the sweat glands serve as excretory organ for heavy metals, organic compounds, and macromolecules. The sweat is composed of 99% water, electrolytes, lactate (provides an acidic pH to resist infection), urea, ammonia, proteolytic enzymes, and other substances.

•  Just one square inch of dermis holds 20 blood vessels.

• Just one square inch of dermis holds more than 1,000 nerve endings that transmit pain, itching, touch and temperature.

• Also contains oil glands that produce sebum to moisturize skin. Sebaceous glands are found on all areas of the skin with the exception of the palms, soles, and dorsa of the feet. Most sebaceous glands have their ducts opening into hair follicles (pilosebaceous apparatus). Free sebaceous glands (not associated with hair follicles) open directly to the surface of the skin.

• The sebum is composed of triglycerides and free fatty acids, wax esters, squalene, and cholesterol. The sebum controls moisture loss from the epidermis by providing the presence of lipids. The sebum also protects against fungal and bacterial infections of the skin due to its contents of free fatty acids.

Inner Layer –Fat Layer

• Under the dermis is fat to provide insulation and store calories.

• Contains lipids, which form a continuous layer surrounding and protecting the corneocytes.

Skin Cancers

• UVA and UVB rays are dangerous and capable of inducing skin cancer. Strong sunburns in early childhood increase risk, however accumulative exposure is a main factor.

• The more moles you have (even if they’re beauty marks), the more you at risk for melanoma skin cancer.

• If your immune system has been weakened (due to chemotherapy, organ transplant, extreme sun exposure, HIV/AIDS or lymphoma), this amplifies your risk of melanoma skin cancer.

Here is the standard gauge for detecting abnormal skin growths: A-B-C-D

Asymmetry (Irregular)

Usually melanoma growths are uneven in their shape.

Border

Usually the border of the growth is jagged, not smooth.

Color

The growth will often have two or more shades (tan, brown, black, translucent, pearly, etc.).

Diameter

Most malignant growths are larger than 1/4 inch in diameter.

Protection Tips

• Don’t sunbathe or frequent tanning parlors. Also avoid exposure in the strongest sun (from 10 am to 3 pm).

• If you’re exposed to sunlight in the 10 am – 3 pm period, wear protective clothing, such as long-sleeved shirt, cotton wrap, sunglasses and a hat with a sufficient brim.

• Protect your skin from harmful ultraviolet sunlight. Use sunscreen year-round before going outdoors. Use sunscreen products with a sun-protection-factor (SPF) of 15 or higher. Also use a lip balm with the same protection factor.

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Sources: Skin Cancer: National Cancer Institute (www.cancer.gov/cancertopics) Melanoma: National Cancer Institute (www.cancer.gov/cancertopics)

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