Bleeding, technically known as hemorrhaging or haemorrhaging (the latter is the preferred international spelling as per the World Health Organisation and many other international medical agencies) (see American and British spelling differences) is the loss of blood from the circulatory system.[1] Bleeding can occur internally, where blood leaks from blood vessels inside the body or externally, either through a natural opening such as the vagina, mouth, nose, or anus, or through a break in the skin. The complete loss of blood is referred to as exsanguination,[2] and desanguination is a massive blood loss. Loss of 10-15% of total blood volume can be endured without clinical sequelae in a healthy person, and blood donation typically takes 8-10% of the donor’s blood volume.
Reference Link : http://en.wikipedia.org/wiki/Main_Page