Explain the counter current mechanism, Science

Assignment Help:

Explain the Counter Current Mechanism?

What is counter current mechanism? Counter current mechanism is the mechanism by which the kidneys produce osmotically concentrated urine. Let us see how. In the proximal convoluted tubule (PCT), the substances like glucose and amino acids are reabsorbed mainly as isotonic solution. Most of the reabsorption occurs here and ' this is the obligatory absorption. If more solute is to be absorbed, more water is reabsorbed and vice versa. This process mainly occurs in the PCT. When the filtrate reaches the loop of Henle, it is still isotonic (having the same or equal osmotic pressure) with the blood plasma. According to Wirz, the filtrate becomes concentrated as it passes down the descending limb of the loop. This portion of the loop lies in the renal medulla and is hyperosmotic with respect to the plasma. Hence water is lost from the descending limb to make the tubular fluid also hyperosmotic.

In the ascending limb, a reverse set of actions occurs as you have already studied earlier under the water balance function of kidneys. The tubule passes from a hyperoslnotic zone to a hypoosmotic zone. To maintain the balance there is an active secretion of sodium chloride unaccompanied by water in the ascending limb, so that the tubular fluid becomes hypoosmotic with the plasma. This mechanism is known as the hair pin counter current multiplier mechanism. The filtrate as it passes down the descending limb of the loop of Henle, gets multiplied in its content of sodium which is through the interstitium and to descending limb through the secretion in the ascending limb. The vasa recta (arterial capillary) act as a counter current exchanger system, faithfully exchanging ions with the interstitium. Through these countercurrent mechanisms, kidney can maintain osmolarity between 300 mOsm/L to 1200 mOsm/L. So far we studied about the contribution of the kidneys in urine formation and its role in maintaining the pH and performing other regulatory functions. Besides these, did you know that the kidneys also have non-excretory functions?


Related Discussions:- Explain the counter current mechanism

Define fats - nutritional components, Define Fats - Nutritional Components ...

Define Fats - Nutritional Components Once the body stops eating, it begins to live on its fat. Fat storing depots 'adipocytes' are located in the different parts of the body. I

Explain Metabolism, Metabolism   All  of  the  organized  chemical  reactio...

Metabolism   All  of  the  organized  chemical  reactions  in  a  cell  which  are under the control of enzymes.

Marasmus, Marasmus: This is caused due to the severe deficiency of bo...

Marasmus: This is caused due to the severe deficiency of both proteins and calories in the diet. Nutritional surveys among pre-school (1 to 5 years) children show that more t

LIBRARY, purpose of different levels of description of an entry

purpose of different levels of description of an entry

Explain the kidney as an endocrine gland, Explain the Kidney as an Endocrin...

Explain the Kidney as an Endocrine Gland The kidney produces substances that can be described as hormones. Hormones are the chemicals produced by glands in the body and circula

Ground depressions in areas of karst topography, Ground depressions in area...

Ground depressions in areas of Karst topography are called: Sinkholes

Explain dacrocystography, Question 1. Why magnification technique is us...

Question 1. Why magnification technique is used in radiography? How it is performed? 2. Explain Dacrocystography. 3. Discuss the pre requisites for fluoroscopic study of

Miscellaneous dangerous substances , Miscellaneous Dangerous Substances : ...

Miscellaneous Dangerous Substances : This was introduced in the United Kingdom to identify other hazardous substances and consists of a black exclamation mark on a white backgroun

Explain the heat loss and bacteriolytic action, Explain the Heat loss and B...

Explain the Heat loss and Bacteriolytic action Heat loss - This is found in dog, sheep etc.  Who do not have sweat glands? In very hot climate, they secrete more saliva (pant

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd