The skin, the largest organ in the human body, serves as a crucial protective barrier against a multitude of external threats. It shields us from microorganisms, prevents dehydration, absorbs ultraviolet light, and protects against mechanical damage.
Protection against microorganisms: The skin's outermost layer, the epidermis, acts as a physical barrier, preventing bacteria, viruses, and fungi from entering the body. [1, 3, 5, 7] This barrier is further enhanced by the skin's natural acidity, which inhibits the growth of many harmful microbes. [6]
Protection against dehydration: The skin plays a vital role in regulating water loss. The outer layer of the epidermis, the stratum corneum, is composed of dead cells tightly packed with keratin, forming a waterproof barrier. [1, 2, 3] This barrier helps to prevent excessive water loss, keeping the body hydrated.
Protection against ultraviolet (UV) light: The skin contains melanin, a pigment that absorbs UV radiation from the sun. [4] Melanin acts as a natural sunscreen, protecting the deeper layers of the skin from damage caused by harmful UV rays. [4]
Protection against mechanical damage: The skin's tough outer layer provides protection from physical trauma such as cuts, scrapes, and abrasions. [1, 2] Additionally, the skin's elasticity allows it to stretch and bend, which helps to prevent tears and other injuries.
In addition to these primary protective functions, the skin also plays a vital role in regulating body temperature, sensing touch, pain, and pressure, and contributing to the immune system. [1, 2, 3, 7]