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

What is the earths core made of, What is the earths core made of? Ans) ...

What is the earths core made of? Ans) The outer earth core is liquid and the inner is solid. Both parts are of alloy of two metals - iron and nickel, permitting the rise of the

Calculate the maximum channel capacity, The Maximum theoretical limit of ch...

The Maximum theoretical limit of channel is governed by Nyquist theorem, which says Bth = 2 x freq in hertz x log2L ( where L = number of level) Thus we have in this case Bth= 2x60

Give the introduction to lipids metabolism, Give the introduction to Lipids...

Give the introduction to Lipids metabolism ? Lipids are a heterogeneous group of organic compounds. The major dietary lipids for humans are animal and plant triacylglycerols,

Earthquakes, Occurrence and characteristics of earthquakes

Occurrence and characteristics of earthquakes

Shut -down sequences for treatment of the spillage site , Shut -down Sequen...

Shut -down Sequences : In some respects, the time when the lab is being shut down is potentially one of the most dangerous periods of the day. For example, at the end of a day's w

Solar family, The Solar Family: Let us now take you on a journey acro...

The Solar Family: Let us now take you on a journey across the universe. We begin from our planet EQrth. It  is our home. The Earth  is active, lush and fertile. It is a place

Roughly circular coral reef enclosing a shallow lagoon, What is the name fo...

What is the name for a roughly circular coral reef enclosing a shallow lagoon: atoll

Keep acid/base concentration of blood constant - kidney, Keep acid/base con...

Keep acid/base concentration of blood constant - Function of Kidney Keep the acid/base concentration of the blood constant and regulate the blood-pressure. Renin, an enzyme- li

What are the effects of temperature variations, What are the Effects of Tem...

What are the Effects of Temperature variations Different minerals present in the rock behave differently to the changing temperatures. The rocks expand on getting heated at day

Geocentric universe of the ancients, Geocentric Universe of  the Ancients:...

Geocentric Universe of  the Ancients: The  earliest ideas of  the Egyptians and Sumerians about the universe may seem strangeto us. The Earth appeared flat 2nd solid tg them.

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