Kidney Kidney The kidneys are two bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood exits into the paired renal veins. Each kidney is attached to a ureter, a tube that carries excreted urine to the bladder. The nephron is the structural and functional unit of the kidney. Each adult kidney contains around 1 million nephrons. The nephron utilizes four processes to alter the blood plasma which flows to it: filtration, reabsorption, secretion, and excretion. The
Bladder pipe into the bladder. While the first creation of a double reed pipe with a bladder controlling breath is unknown, it is believed to have originated in Europe before the 13th century. As an intermediate phase between the almost pan-European bagpipe and the Renaissance crumhorn, the Bladder pipe flourished from the 14th to 16th centuries. Examples have been found from Germany, Poland, England, France, Italy, Spain (called the odrecillo) and Estonia (called the rakkopilli). As it declined in popularity, it became associated with beggars and peasants. The early bladder pipe is in a family of the early medieval "chorus" instruments, a