Dermatology

Dermatology is a medical specialty dealing with the diagnosis and treatment of diseases of the skin. These are conditions of the

skin such as rashes,acne,warts,moles,skin cancers, etc.

Dermatology developed as a subspecialty of internal medicine in the 18th century; it was initially combined with the

diagnosis and treatment of venereal diseases because syphilis was an important possible diagnosis in any skin rash. It's scientific

basis however was not established until the mid-19th Century by the Austrian physician Ferdinand Von Hebra. Hebra emphasized

an approach to skin diseases based on the microscopic examination of the skin. Modern dermatology emerged in the early 20th

Century, after the discovery of an effective drug therapy for syphilis. Due to the ease of observation and contaneous symptoms,

dermatology has become a separate branch of medicine.

The human body's largest organ is the skin. All vertebrates have skin, though the covering in each species has different features, such as scales,feathers or fur.

The skin protects body tissues against injuries and helps regulate body temperature by making pores larger or smaller. The nerves in skin receive the stimuli that are then interpreted by the brain as touch, heat and cold. Skin is composed of three layers: epidermis, dermis, and subcutaneous fatty tissue.

The outer layer, the epidermis, is constantly flaking off and being renewed from the dermis. The epidermis itself has four layers. The outermost layer is the stratum corneum composed of flattened dead cells that act as a barrier against light and heat energy and protect the body from water loss, microorganisms and

many chemicals. The second layer of the epidermis, the stratum granulosum has granules of Keratohyalin- a substance found in hair, nails, and other horny structures in the cells. The third papillae, tiny projections that fit the dermis to the epidermis like parts of a puzzle. These projections are especially prominent on the

palms of the hands and soles of the feet where the epidermis is ridged and furrowed in patterns of tiny whorls and loops. These patterns are what form each persons unique set of fingerprints and

footprints.

Subcutaneous fatty tissue is the deepest layer of skin. It is composed of connective tissue, blood vessels, and fat cells. This layer binds the skin to underlying structures, insulates the body from cold and stores energy in the form of fat.

Nails, like the claws, hoofs and horns of animals are merely thickened and hardened epidermis. Nails are protected by cuticles

or proximal nailfolds. Goosebumps occur when tiny hair-erector muscles contract in response to cold, excitement or fear.

Two sets of glands discharge secretions through the skin. Sebaceous or oil glands arise from the walls of hair follicles and

produce an oil called sebum that lubricates the skin and hair. Sweat

galnds, embedded in the subcutaneous layer are scattered all over the body, particularly in the palms and soles. Sweat glans produce

moisture called perspiration that reaches the skins surface through the pores and evaporates to cool the body. Secretions from some

sweat glands also produce a characteristic odor.

The skin is susceptible to a variety of disorders, including allergic rashes, such as chronic skin diseases as psoriasis, such

fungal infections as athletes foot, ringworm and warts. Viruses can produce the painful skin blisters known as shingles. Viruses also

cause cold sores, which are eruptions on the lip or in the mouth. Acne, an inflammation of sebaceous glands is common during

adolescence and results from increased oil production.

Repeated overexposure to the sun over a long period of time- even exposure that results in tanning not sunburn- causes

premature aging of the skin. The skin becomes wrinkled and the overall depth of the layers of the skin is reduced. Discolored nodules may also develop.

Sunburn is skin damage caused by reaction to the ultraviolet or UV radiation in sunlight. When the skin is overexposed to the sun,

ultraviolet radiation from the sun destroys the outerlayers of the skin. Tiny blood vessels beneath the skin are also damaged.

Sunburn can best be prevented by avoiding overexposure to the sun. Sunscreens can also be used to help prevent sunburn. These

are not the same as sun tanning lotions, which are designed to aid in tanning and to moisturize the skin. The main substance in sunscreens is para-aminobenzoic acid(PBA). This substance

absorbs the UV rays of the sun and prevents them from entering the skin. Other sunscreens may contain titanium doxide, which

protects the skin by reflecting the sun's rays.

The skin's condition influences a person's general health. Preparations for the care of the skin form a major portion of

cosmetics. They include cleansing creams, lotions and milks. Emollients are heavier cold creams that help prevent water loss from the skin. Hand creams counter act dryness from exposure to wind, sun, and detergents. One should wash the face daily and cleanse the skin well in order to maintain healthy skin.