Blood has a matrix and it helps in of gases, food, and waste materials.
So far Sally learnt about transport of food, oxygen and water via blood. But she still wasn't clear about how blood acted as a medium for removal of waste materials from the body. She asked the doctor about the same. The doctor said that blood collects the waste material from the tissues and takes it to the ___________ where it is filtered out of the blood capillaries whereas useful materials are retained by the blood.