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

Soundwaves.., Temperature affects the _____ of sound waves !?

Temperature affects the _____ of sound waves !?

Write the purposes of conditioning of wheat prior to milling, Q. Write the ...

Q. Write the purposes of conditioning of wheat prior to milling? The purpose of conditioning of wheat prior to milling are to make the bran and germ pliable, thus preventing th

Define pus - abnormal constituent of urine, Define pus - abnormal constitue...

Define pus - abnormal constituent of urine Pus: Pus cells are found in the urine in infections of urinary tract. Pus is actually a viscous, yellowish-white fluid formed in infe

Observe the surface of the moon, Observe the surface of the moon :- Use ...

Observe the surface of the moon :- Use the small telescope or a pair of field glasses. Examine the surface of the moon and see if you can see any of its craters and mountains.

Types of energy, give examples for one energy transformed to another energy...

give examples for one energy transformed to another energy

Wheat flour, why- 1) alcoholic acidity is determined? 2) ash content is imp...

why- 1) alcoholic acidity is determined? 2) ash content is important factor in wheat flour? 3)carbohydrates and sugar are separately denoted on pachaging material?

EDTA.., principle of EDTA..

principle of EDTA..

When does an atoll start to form, When does an atoll start to form? Thi...

When does an atoll start to form? This starts to form when tiny marine animals - coral polyps - attach themselves to rocks on the seabed.

What is first aid, What is First Aid? First-aid is the immediate and te...

What is First Aid? First-aid is the immediate and temporary care given to the victim of an accident or sudden illness. Its purpose is to (1) help preserve life, (2) preve

Social role of communication, Social Role of Communication: Social  r...

Social Role of Communication: Social  relevance of communication follows from the economic and political role of communication. We, in this country, have often talked about u

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