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.
Subfornical organ columns and body of the fornix. Afferent fibers from the body and columns of the fornix polysynaptically excite both superficial and deep neurons. A recurrent inhibitory circuit is suggested on the output path. The expression of various genes in the subfornical organ have been studied. For example, it was seen that water deprivation in rats led to an upregulation of the mRNA that codes for angiotensin II receptors, allowing for a lower angiotensin concentration in the blood that produce the "thirst" response. It also has been observed to be a site of thyroid transcription factor 1 (TTF1) production, a protein