How many milliliters of blood is there in the human body?

Healthy people's blood accounts for about 8% of their weight. In other words, a healthy person weighing 50 kilograms has about 4000 milliliters of blood. Normally, 80% blood flows in the heart and blood vessels to maintain normal physiological functions, and 20% blood is stored in organs such as the liver and spleen. Once blood loss or physical activity increases, these stored blood will enter the blood circulation.