Dialysis blocks the passage of larger substances (for example, red blood cells, large proteins). This replicates the filtering process that takes place in the kidneys when the blood enters the kidneys and the larger substances are separated from the smaller ones in the glomerulus. The two main types of dialysis, hemodialysis and peritoneal dialysis, remove wastes and excess water from the blood in different ways. Hemodialysis removes wastes and water by circulating blood outside the body through an external filter, called a dialyzer, that contains a semipermeable membrane. The blood flows in one direction and the dialysate flows in the opposite.
Pipe organ can be viewed at List of pipe organs. The origins of the pipe organ can be traced back to the water organ in Ancient Greece, in the 3rd century BC, in which the wind supply was created with water pressure. By the 6th or 7th century AD, bellows were used to supply organs with wind. Beginning in the 12th century, the organ began to evolve into a complex instrument capable of producing different timbres. A pipe organ with "great leaden pipes" was sent to the West by the Byzantine emperor Constantine V as a gift to Pepin the Short, King