Uriniferous tubule is both the nephron and collecting duct, it is the functional unit of the kidney.
Their function is to purify the blood i.e remove all the metabolic waste in the form of urine.
It consists of the following parts : renal corpuscle(glomerulus and Bowman’s capsule), PCT (proximal convoluted tubule), Henle’s loop, DCT(Distal convoluted tubule) and collecting duct.
The first step in urine formation is the filtration of blood which is carried by glomerular. It is called glomerular filtration.
Then the filtrate has to pass through the epithelial cells of Bowman’s capsule which are arranged in an intricate manner so that minute pores are only present. This is ultrafiltration of the blood.
Then the filtrate is passed to PCT where reabsorption takes place. Nearly 70-80 percent of electrolytes and water are reabsorbed by this segment.
Then it passes through Henle’s loop where it plays a significant role in maintaining the osmolarity of medullary interstitial fluid.
The descending limb of the loop is permeable to water but almost impermeable to electrolytes.
The ascending limb of the loop of Henle is impermeable to water but permeable to electrolytes. The filtrate as it passes towards DCT becomes diluted.
In DCT there is conditional reabsorption of ions and selective secretion takes place to maintain the pH and sodium- potassium balance in the blood.
The DCT of many nephrons opens into a collection duct where large amounts of water are reabsorbed and it makes urine concentrated.
And so urine passes from the collecting duct to the renal pelvis to the ureter and further outside the body.
Final Answer:
Uriniferous tubule in nephron plus collecting duct. It purifies the blood.