One function of the kidneys is to "cleanse" the blood or filter it. Where does this process occur?
Cleansing or filtering of the blood takes place in the nephron, the basic functional unit of the kidney.
The kidney is made up of around a million nephrons which are the basic functional units of the kidney where filtration of blood takes place.
The nephron is comprised of a glomerulus (a capillary network with an afferent arteriole at one end and an efferent arteriole at the other end), which is surrounded by a Bowman's capsule (or Glomerular capsule).
The Bowman's capsule is double walled so as to form a capsular space within the walls that leads to a tube called the renal tubule which conducts the filtrate towards the ureter.
The interface between the capillaries of the glomerulus and the wall of the Bowman's capsule is a filtration membrane through which water and solutes pass from the blood into the capsular space.