Question

Read the following functions and identify the part of nephron responsible for it.
$A.$ Nearly all of the essential nutrients and 70-80% of electrolytes and water are reabsorbed by this segment.
$B.$ Conditional reabsorption of $N a^{+}$ and water takes place in this segment.
$C.$ Large amounts of water could be reabsorbed from this region to produce concentrated urine.

• A. Loop of Henle
• B. Collecting duct
• C. Collecting duct
• D. Loop of Henle

Answer 1

Answer: (B)

A. Functions of Proximal Convoluted Tubule (PCT)
$1.$ PCT absorbs almost all essential nutrients.
$2.$ PCT absorbs about 70-80 % electrolytes and water.
$3.$ As PCT selectively secretes H+ ions, ammonia and potassium ions into the filtrate and also absorbs $H C O_{3}^{-}$
from it, it maintains the pH and ionic balance of the body fluids.
B. Functions of Henle's Loop
$1.$ Maintenance of high osmolarity of medullary interstitial fluid.
$2.$ Reabsorption to some extent (some water and electrolytes enter medullary fluid).
C. Functions of Distal Convoluted Tubule (DCT)
$1.$ Conditional reabsorption of $N a^{+}$ and water.
$2.$ Reabsorption of $H C O_{3}^{-}$ and selective secretion of $H^{+}, \, K^{+,}$ and $N H_{3}$ for maintaining the pH and sodium-potassium balance in the blood.
D. Functions of Collecting Duct
$1.$ Reabsorbed of large amounts of water resulting in the production of concentrated urine.
$2.$ Small amounts of urea enter the medullary interstitium to keep up the osmolarity.
$3.$ By the selective secretion of $H^{+}$ and $K^{+}$ ions, collecting ducts also plays an important role in the maintenance of pH and ionic balance of the blood.