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.
Contusions to the brain resulting from a blow to the head can result in a traumatic brain injury (TBI). Concerns when you suffer a laceration include bleeding, infection, pain, damage to structure beneath the skin, and future scars. A deep cut may expose underlying tissues, such as fat, tendon, muscle, or bone.