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.
Jehovah's Witnesses and blood transfusions Society in which it states: "Consider a man who is told by the doctor that he must abstain from alcohol. Would he be obedient if he quit drinking alcohol but had it put directly into his veins?" Muramoto says the analogy is false, explaining: "Orally ingested alcohol is absorbed as alcohol and circulated as such in the blood, whereas orally eaten blood is digested and does not enter the circulation as blood. Blood introduced directly into the veins circulates and functions as blood, not as nutrition. Hence, blood transfusion is a form of cellular organ transplantation. And ... organ transplants