Tissue: A group or layer of cells that perform specific functions. For example, muscle tissue is a group of muscle cells.issue: A group or layer of cells that perform specific functions. For example, muscle tissue is a group of muscle cells.
1 The skin is a barrier to the outside world protecting the body from infection, radiation, and extremes of temperature.  There are many types of wounds that can damage the skin including abrasions, lacerations, rupture injuries, punctures, and penetrating wounds.
Causes and types of scrapes. Scrapes (abrasions) are skin wounds that rub or tear off skin. Most scrapes are shallow and do not extend far into the skin, but some may remove several layers of skin. Usually there is little bleeding from a scrape, but it may ooze pinkish fluid.