The Skin 2014 WebMD, llc. All rights reserved. Prev

Skin Tests

• 
  Skin biopsy: A piece of skin is removed and examined under a microscope to identify a skin condition.
  
• 
  Skin testing (allergy testing): Extracts of common substances (such as pollen) are applied to the skin, and any allergic reactions are observed.
  
• 
  Tuberculosis skin test (purified protein derivative or PPD): Proteins from the tuberculosis (TB) bacteria are injected under the skin. In someone who’s had TB, the skin becomes firm.
  

Skin Treatments

• 
  Corticosteroids (steroids): Medicines that reduce immune system activity may improve dermatitis. Topical steroids are most often used.
  
• 
  Antibiotics: Medicines that can kill the bacteria causing cellulitis and other skin infections.
  
• 
  Antiviral drugs: Medicines can suppress the activity of the herpes virus, reducing symptoms.
  
• 
  Antifungal drugs: Topical creams can cure most fungal skin infections. Occasionally, oral medicines may be needed.
  
• 
  Antihistamines: Oral or topical medicines can block histamine, a substance that causes itching.
  

Facts about the skin

The skin is the body's largest organ. It covers the entire body. It serves as a protective shield against heat, light, injury, and infection. The skin also:

• 
  Regulates body temperature
  
• 
  Stores water and fat
  
• 
  Is a sensory organ
  
• 
  Prevents water loss
  
• 
  Prevents entry of bacteria
  
• 
  Acts as a barrier between the organism and its environment
  
• 
  Helps to make vitamin D when exposed to the sun
  

Your skin takes on different thickness, color, and texture all over your body. For example, your head contains more hair follicles than anywhere else. But the soles of your feet have none. In addition, the soles of your feet and the palms of your hands are much thicker than skin on other areas of your body.
The skin is made up of 3 layers. Each layer has certain functions:

• 
  Epidermis
  
• 
  Dermis
  
• 
  Subcutaneous fat layer (hypodermis)
  

Epidermis

The epidermis is the thin outer layer of the skin. It consists of 3 types of cells: