The human body needs blood to live. The body can compensate for a sudden loss – but only up to a certain amount. After that, only transfusions help, otherwise it becomes life-threatening.
We couldn’t live without blood: it transports oxygen as well as important nutrients, waste products and hormones. Almost seven percent of a person’s body weight consists of the red fluid; in an adult male body that is around 5.6 liters and in an adult female body around 4.5 liters. A newborn baby carries about a cup of blood.
On average, an adult human body consists of about five liters of blood – which flows through 100,000 kilometers of blood vessels throughout the body.
More than 1.5 liters is critical
For example, if someone loses blood through an accident , internal bleeding or during an operation, they can withstand a certain amount. A healthy adult can lose up to 1.5 liters without causing serious damage. But if it is more than 1.5 liters, the organs are no longer adequately supplied with oxygen. In this case, blood transfusions are necessary, otherwise blood loss can be fatal.When you donate blood, half a liter is usually taken. This takes between five and ten minutes. The fluid is formed again in the body within a few hours.