1 A blood clot that forms inside one of your veins or arteries is called a thrombus. A thrombus may also form in your heart.  A thrombus that breaks loose and travels from one location in the body to another is called an embolus.
The kidneys. The kidneys do vital work in the body filtering blood removing waste into urine, and balancing electrolyte levels. Our blood in our bodies passes through the kidneys several times a day. The kidneys are located at the back of the abdomen. Each kidney is about the size of a fist - 10-12.5cm long.
The kidneys are bean-shaped organs (about 11 cm x 7 cm x 3 cm) that are located against the back muscles in the upper abdominal area. They sit opposite each other on both the left and right side of the body; the right kidney, however, sits a little lower than the left to accommodate the size of the liver. Medscape.