Give a brief account of the counter-current mechanism.
Answer:
The mechanism used by the kidneys to concentrate urine is called the counter current mechanism.
- The Henle’s loop and vasa recta play a significant role in this. The flow of filtrate in the two limbs of Henle’s loop is in opposite directions and thus forms a counter current. The flow of blood through the two limbs of vasa recta is also in a counter current pattern.
- The proximity between the Henle’s loop and vasa recta, as well as the counter current in them help in maintaining an increasing osmolarity towards the inner medullary interstitium, i.e., from 300 mOsmolL–1 in the cortex to about 1200 mOsmolL–1 in the inner medulla. This gradient is mainly caused by NaCl and urea.
- NaCl is transported by the ascending limb of Henle’s loop which is exchanged with the descending limb of vasa recta. NaCl is returned to the interstitium by the ascending portion of vasa recta. Similarly, small amounts of urea enter the thin segment of the ascending limb of Henle’s loop which is transported back to the interstitium by the collecting tubule.
- The above described transport of substances facilitated by the special arrangement of Henle’s loop and vasa recta is called the counter-current mechanism.
NCERT Solutions for Class 11 Biology Chapter 16 Excretory Products and Their Elimination
NCERT Solutions for class 11 Biology Chapter-16: Excretory Products and their Elimination: The chapter on Excretory Products and their Elimination is important for students approaching the board exams. This article introduces NCERT solutions designed to help students explain the concepts of further learning and how to write to get good grades on exams. The solutions are presented in very simple language for ease of understanding.
NCERT CBSE Chapter 16 Excretory Products and their Elimination of Class 11 Biology discusses the concept of excretion and explains the excretory functions of the skin, liver, large intestine, lungs, and kidneys. It also describes the other organs of the urinary system and several urinary system disorders. Revise the basic concepts of Excretory Products and their Elimination for quick revision and class notes.
Contact Us