Bleeding

Bleeding, technically known as Hemorrhage (American English) or Haemorrhage (British English) is the loss of blood from the circulatory system. Bleeding can occur internally, where blood leaks from blood vessels inside the body or externally, either through a natural opening such as vagina, mouth or rectum, or through a break in the skin. The complete loss of blood is referred to as exsanguination.

The average human has around 7 to 8% of their body weight made up of blood. This equates to an average of around 5 liters of blood (5.3 quarts) in a 70kg (154 lbs) man. The circulating blood volume is approximately 70 ml / kg of ideal body weight. Thus the average 70 kg male has approximately 5000 ml (5.3 quarts) of circulating blood. 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.

The human body generates blood at a rate of about 2 litres (2.1 quarts) per week. The technique of blood transfusion is used to replace severe quantities of lost blood.