Skin

One of the primary functions of the skin is to act as a protective barrier. It prevents the entry of harmful microorganisms and reduces the loss of essential fluids. The outermost layer, the epidermis, contains keratinocytes that produce keratin, which provides toughness and resilience. Additionally, skin is involved in thermoregulation; it helps maintain the body's temperature through mechanisms such as sweating and blood flow regulation. The skin’s rich nerve endings allow for sensory perception, enabling the detection of heat, pressure, and pain. Furthermore, it plays a role in vitamin D synthesis through exposure to sunlight, essential for calcium metabolism and bone health.

Skin covers the entire external surface of the body, accounting for about 16% of total body weight in adults. It consists of different regions, including the scalp, face, neck, torso, arms, and legs. The thickness of skin varies across different parts of the body; for example, the skin on the palms of the hands and soles of the feet is thicker than that on the eyelids. The skin is anchored to underlying structures, such as muscles and bones, by the subcutis, which contains fat and connective tissue, providing insulation and shock absorption.

• The average adult has approximately 2 square meters of skin covering their body.
• Skin continues to regenerate throughout a person's life, shedding millions of dead cells daily.
• Skin can detect even the slightest changes in temperature and pressure, making it a highly sensitive organ.
• The color of skin is primarily determined by the amount of a pigment called melanin, produced by specialized cells in the epidermis.
• Skin is not just a passive barrier; it can actively participate in immune responses.