Question

Vital morphological and physiological unit of mammalian kidneys are
A. ureters
B. Seminiferous tubules
C. Uriniferous tubules
D. Nephridia

Answer 1

Hint: The mammalian kidneys are a pair of bean-shaped structures that filter blood and purify it. To perform this function, it has a network of blood vessels, an important component of its structure and function.

Complete Answer:
- Kidneys contain millions of individual nephrons to concentrate urine from the blood. Each nephron contains blood vessels and a special tubule to purify the blood, remove waste and absorb the nutrients into the blood. Each nephron has two parts: glomerulus and the renal tubule.
- The glomerulus is a tuft of capillaries formed by afferent, which brings blood into the glomerulus, and efferent arteriole, which takes away the blood. The glomerulus is enclosed by Bowman’s capsule and together they are called the renal corpuscle. It further continues to form a renal tubule which contains: PCT, Henle’s loop, and DCT.
- In the Bowman’s capsule, ultrafiltration is done. The blood is filtered so finely in it that almost all the constituents of the plasma except protein pass into the lumen of Bowman’s capsule. After that, the fluid moves into the proximal convoluted tubules (PCT) where selective reabsorption takes place followed by the recovery of water and sodium chloride from the urine in Henle’s loop.
- The fluid then moves into the distal convoluted tubules (DCT) where usable material is reabsorbed (same as that of PCT). As the filtrate flows through the tubule of nephron, it becomes increasingly concentrated into urine. Each nephron is connected to the collecting duct which helps in water retention and small amounts of urea are also absorbed. Nephron is called a uriniferous tubule.

Hence, the correct answer is option C i.e. uriniferous tubules which are the vital morphological and physiological units of mammalian kidneys.

Note: Nephron along with the collecting duct is called uriniferous tubules. Due to this function of uriniferous tubules, of producing urine in the process of removing waste and excess substances from the blood, it is called as the morphological and physiological units of mammalian kidney.