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 excretion, blood volume regulation, and vasopressin secretion. The SFO is outside the blood–brain barrier, and so neuronal hormone receptors in this region can respond to factors present in the systemic circulation. The circumventricular organs express high density of Glucagon-like peptide 1 (GLP-1)receptors and participate in the central regulation of energy intake. Neurons in the subfornical organ have receptors for many hormones that circulate in the blood but which do not cross the blood–brain barrier, including angiotensin, atrial natriuretic peptide, endothelin and relaxin. The role of the SFO in angiotensin regulation is particularly important, as it is involved in communication with