And on top of that, these same copper cells can also recycle and break down the old red blood cells that no longer function properly. So these red blood cells are also known as erythrocytes. Now, function number four of the liver is to basically store important types of vitamins such as, for example, vitamin D, as well as iron that are essential for our body. Now, earlier we mentioned in a previous lecture, we basically mentioned that our liver can also act as an endocrine gland. It can produce a special type of enzyme, special type of protein that acts as a hormone. So basically, liver produces thrombopolietin, which is a glycoprotein hormone that is responsible for controlling the blood clotting cascade, as we'll see in a future lecture.