The skin is the largest organ in the human body, covering the entire surface and serving as the first line of defense against external factors. In adults, it has an average area of about two square meters and makes up nearly 16% of total body weight, making it an essential component of life.<br />Layers of the Skin<br />The skin is composed of three main layers:<br />1. Epidermis – the outer layer that protects against microbes and prevents water loss.<br />2. Dermis – contains blood vessels, nerves, sweat glands, and hair follicles.<br />3. Subcutaneous tissue (fat layer) – acts as insulation and an energy reserve.<br />Amazing Functions of the Skin<br />• Protection: Shields the body from bacteria, viruses, and harmful UV rays.<br />• Temperature regulation: Maintains body heat through sweating and blood vessel dilation or constriction.<br />• Sensation: Packed with millions of nerve endings that detect heat, cold, pressure, and pain.<br />• Excretion: Helps eliminate waste products through sweat.<br />• Vitamin D production: When exposed to sunlight, the skin produces vitamin D, vital for bone and immune health.<br />Fascinating Facts<br />• The epidermis renews itself approximately every 28 days.<br />• Skin thickness and color vary among individuals based on genetics and environment.<br />• Fingerprints are unique to each person and never repeat.<br /><br /><br />Al _ Mustaqbal University, the first university in Iraq<br />Prepared by: Shahad Nawras Abbas<br />