The kidney consists of a very large number of uriniferous tubes called nephrons. Each nephron is a highly convoluted structure. It begins as a blind-ended round double cup like structure called Bowman's capsule containing a capillary network called glomerulus, formed from the afferent and efferent arterioles.

Bowman's capsule leads into a coiled portion called the proximal convoluted tubule (p.c.t). It is followed by a U-shaped Henry's loop made up of descending and ascending limbs. The later continues into the distal convoluted tubule (d.c.t) which finally opens into the collecting tubule. The collecting tubules from various nephrons form collecting ducts which eventually open into the pelvis. Ureters descends down from the pelvis and open into the urinary bladder.