It also produces prothrombin and
fibrinogen, both blood-clotting factors, and
heparin, a mucopolysaccharide sulfuric acid
ester that helps keep blood from clotting within the circulatory system.
The liver converts sugar into glycogen, which it stores up until the muscles need energy, when it is secreted into the blood stream as glucose
. The liver synthesizes proteins and cholesterol and converts carbohydrates and proteins into fats, which are stored for later use.