The skin is the largest organ in the human body and weighs about 8 to 10 pounds.

The skin makes up about 15% of your total body weight. It has three main layers called the epidermis, the dermis, and the hypodermis. The outer layer is very thin on your eyelids but much thicker on the palms of your hands. This layer contains melanin, which helps block damage from the sun.Your skin helps you stay cool by using 2 to 4 million sweat glands. When you get too hot, these glands release water that evaporates to cool you down. The middle layer of skin contains over 11 miles of tiny blood vessels. These vessels shrink when you are cold to keep heat inside your body.The skin is also a giant sensor for your brain. It has special parts that feel light touches and others that feel heavy pressure. It even makes Vitamin D when sunlight hits it, which keeps your bones strong. The surface of your skin is slightly acidic to stop bad bacteria from growing on you.