The Systems of the Body
The Integumentary System
Back to the Basics - Our Body

by Catherine M. Hren, MD
May 2010

The name might not look familiar, but you are very well acquainted with your integumentary system. Made up of the skin, hair, nails, and associated glands, the integumentary system is the most visible organ system. It is also one of the most diverse, ranging from a thin strand of hair to the thick sole of the foot. The responsibilities of the integumentary system include protecting the body from the outside world and harmful substances, regulating body temperature, and acting as an excretory organ (by secreting salt, water, and wastes in the form of sweat).

The Components

• SKIN — The skin is the largest and heaviest organ of the human body. The skin of the palms of the hands and soles of the feet can be up to 0.2 inches thick and is appropriately termed thick skin. The rest of the body’s skin ranges from 0.04 to 0.08 inches — thin skin. The skin is made up of two principal layers — the epidermis and the dermis. The epidermis is the thin, outer layer, and the dermis is the thicker, inner layer. The dermis is where the hair, sweat glands, and sebaceous (oil) glands are rooted.
• HAIR — Hair covers almost every part of the body, except the palms of the hands, the soles of the feet, the sides of the fingers and toes, the lips, and certain parts of the genital organs. Each hair originates from a hair follicle in the dermal layer. Body hair is valuable for the preservation of heat and protection from abrasions and UV rays. Eyelashes, eyebrows, and hair in the ears and nose also protect these sensitive areas from dust and other small particles.
• NAILS — The nail plate consists of dead cells, but the nail bed (underneath the nail plate) is alive. The blood vessels in the nail bed are what give the nail body a pink color. Nails protect the sensitive tips of the fingers and toes and aid in picking up objects.
• SWEAT GLANDS — There are more than 2.5 million sweat glands on the surface of the human body. They consist of two types: eccrine sweat glands and apocrine sweat glands. Eccrine glands are found all over the body but are most numerous on the forehead, upper lip, palms, and soles. Apocrine glands are located in the armpits, around the nipples, and in the groin. These glands do not function until puberty. If secretion from the aprocine glands remains on the skin for any length of time, bacteria grows, creating the unpleasant odor associated with sweat.
• SEBACEOUS GLANDS — Commonly referred to as the oil glands, the sebaceous glands secrete sebum — a mixture of lipids, proteins, and fragments of dead fat-producing cells — which prevents the drying of the skin and hair. Sebum also contains chemicals that kill bacteria on the skin’s surface.

Integumentary System Problems
SKIN CANCER — Skin cancer is the most common type of human cancer. Warning signs include new growths or sores that do not heal. Most commonly caused by the ultraviolet (UV) rays in sunlight, these growths usually appear on the face, neck, hands, and arms — the areas often exposed to the sun.

Treatment of skin cancer has a success rate of 90% or more. Common treatment methods include curettage (scooping out the affected area) and desiccation (additional application of electric currents to manage bleeding and kill the remaining cancer cells), surgical excision, radiation therapy, and cryosurgery (freezing the cancer cells).

PSORIASIS — Psoriasis is a condition that causes redness and irritation of the skin. It is often characterized by thick, red skin with flaky, silver-white patches. These skin changes may also be associated with joint pain and nail changes, such as yellow-brown spots or dents on the nail surface.

Mild cases of psoriasis are usually treated with steroid creams, such as Cortisone, or prescription medicines containing vitamin D or vitamin A.

ALOPECIA — Alopecia is defined as the loss of hair from the head or body. Though alopecia is most often a hereditary condition affecting men, it can be caused by a variety of factors including poor nutrition, overexposure to chemicals or heat, menopause or radiation therapy.

The first step in treating alopecia is determining the cause. This may allow the individual to change factors, such as diet or medication, which are influencing the condition. Additionally, there are many pills and creams marketed for hair loss treatment which have varying degrees of success.

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Catherine M. Hren, M. D. is with the Cary Dermatology Center, P. A., 919.467.8556, carydermatology.com

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