What is the function of Bowman's capsule and Glomerulus?

The renal tubule begins with a double walled cup-like structure called Bowman's capsule which encloses the glomerulus. Glomerulus along with Bowman's capsule is called the Malpighian body or renal corpuscle. The first step in urine formation is the filtration of blood, which is carried out by the glomerulus and is called glomerular filtration. The glomerular capillary blood pressure causes filtration of blood through 3 layers, i.e., the endothelium of glomerular blood vessels, the epithelium of Bowman's capsule and a basement membrane between these two layers. The epithelial cells of Bowman's capsule called podocytes are arranged in an intricate manner so as to leave some minute spaces called filtration slits or slit pores. Blood is filtered so finely through these membranes, that almost all the constituents of the plasma except the proteins pass onto the lumen of the Bowman's capsule.