Now that you understand the two layers of skin that wrap your body, you can make sense of a whole host of skin insults and injuries.
• Cuts. Shallow cuts that don’t dig past the epidermis won’t produce any blood. Instead, your skin will just ooze clear liquid. If you see blood, you’ve hit the much thicker and much tougher dermis.
• Stretch marks. Extreme skin stretching (for example, stretching caused by extreme weight gain or pregnancy), can tear the dermis, leaving stretch marks behind. Although they fade with time and are completely harmless, stretch marks never disappear. (Incidentally, 75 to 90 percent of women get some sort of stretch marks during pregnancy. Special skin creams seem to offer little help, and the natural elasticity of your skin appears to determine how severely you’re affected.)
• Blisters. A blister is a fluid-filled pocket that forms between the epidermis and the dermis. The culprit is usually friction from a repetitive motion. Blisters heal fastest (and with no chance of infection) if you leave them undisturbed and unbroken.
• Bruises. A bruise is an injury that causes blood to seep from damaged tissue into the dermis. The bruise remains until your body reabsorbs the blood.
• Warts. A wart is a small, rough skin tumor that’s usually triggered by a virus (and you usually pick up that virus from a damp surface, like a community swimming pool). Warts are more likely to cause pain and embarrassment than any serious complications. However, they can be tenacious, especially those that appear on the undersides of your feet. If you can’t kill off a wart with the standard, over-thecounter products, visit your doctor for a more powerful approach, like a dab of super-cold liquid nitrogen.
Source of Information : Oreilly - Your Body Missing Manual