Overview
The skin is our largest organ, covering an average area of 22 square feet and weighing roughly eight pounds. Its waterproof nature and rapid regenerative powers give us front-line protection from a variety of disease-causing organisms. In addition, certain components in our skin seek out potential sources of disease and identify them to powerful elements of our immune systems.
Skin Components
Your skin is composed of three separate layers that extend inward from the surface: the protective epidermis; the dermis, which nourishes the epidermis and gives skin its elasticity; and the subcutaneous layer, which stores fat, protects against physical trauma and helps control body temperatures, according to the Nemours Foundation. In addition to cells called melanocytes, which provide skin pigment, the epidermis contains cells called keratinocytes, which also form the basis of your nails and hair. The durable qualities of these keratinocytes help give skin its integrity and protective strength.
Langerhans’ Cells
The epidermis also contains specialized cells called Langerhans’ cells, according to the Merck Manual for Healthcare Professionals. When potentially harmful substances such as viruses, bacteria or chemicals come in contact with your skin, Langerhans’ cells take samples of these substances and relay them from the skin to nearby lymph nodes. In the lymph nodes, immune system components called T-cells respond to the presence of the harmful substances and activate your body’s immune response.
Replacement and Repair
In the epidermis, four layers of keratinocytes continually die and renew, sloughing off old skin cells and replacing them completely over a period of roughly 28 days, the Nemours Foundation reports. This rapid process of replacement allows your skin to quickly repair breaches to its integrity such as scrapes and cuts, thereby sealing off possible avenues of disease and infection.
Considerations
Severe damage to your skin can extend past the epidermis down into the dermis. If this damage occurs in blood-rich areas of the body, your skin will likely still repair itself and maintain a barrier against infection, according to the National Skin Care Institute. However, deeper damage to your skin may also trigger the formation of scar tissue, which cannot provide the same level of skin function or infection resistance.
Additional Considerations
Abnormal dryness can drastically reduce your skin’s protective abilities, potentially producing symptoms such as inflammation, irritation and cracking and peeling of the skin’s surface, according to the U.S. National Library of Medicine. Potential causes of dry skin include use of harsh soaps, frequent bathing, low environmental humidity and the presence of the skin rash called eczema.
