What is the countercurrent mechanism of the loop of Henle?
The loop of Henle utilizes the countercurrent multiplier system to increase the concentration of solute and ions within the interstitium of the medulla. This ultimately allows the nephron to reabsorb more water and concentrate the urine while at the same time using as little energy as possible.
What is countercurrent flow in the kidney?
Because the blood flow through these capillaries is very slow, any solutes that are reabsorbed into the bloodstream have time to diffuse back into the interstitial fluid, which maintains the solute concentration gradient in the medulla. This passive process is known as countercurrent exchange.
What forms the countercurrent in kidney?
There are two countercurrent mechanisms in the kidneys. They ‘re the loop of Henle and the vasa recta. Henle’s loop is a U-shaped part of the nephron. Blood flows in opposite directions in the two limbs of the vessel, giving rise to counter-currents.
Where is countercurrent exchange in the kidney?
It is generally accepted that the microcirculation of the renal medulla functions as a countercurrent exchanger that traps NaCl and urea deposited to the interstitium by the loops of Henle and collecting ducts, respectively.
What is the purpose of the loop of Henle?
The primary function of the loops of Henle and the thick ascending limb of the distal tubule is the concentration of urine utilizing a principle called ‘countercurrent multiplication. ‘ The medulla possesses a gradient of urea and salt with increasing concentrations of these solutes closer to the papillae.
Why is countercurrent flow effective?
The counter-current method is the most efficient because it maintains the same concentration gradient along the entire length of the circuit. The difference in efficiency (in terms of urea clearance) is approximately 20% in modern filters, when comparing concurrent and countercurrent arrangements.
What is the function of countercurrent multiplier?
The counter-current multiplier or the countercurrent mechanism is used to concentrate urine in the kidneys by the nephrons of the human excretory system. The nephrons involved in the formation of concentrated urine extend all the way from the cortex of the kidney to the medulla and are accompanied by vasa recta.
Where is countercurrent exchange found in the body?
The arteries of our arms and legs run parallel to a set of deep veins. As warm blood passes down the arteries, the blood gives up some of its heat to the colder blood returning from the extremities in these veins. Such a mechanism is called a countercurrent heat exchanger.
What is the function of Bowman’s capsule?
Bowman’s capsule surrounds the glomerular capillary loops and participates in the filtration of blood from the glomerular capillaries. Bowman’s capsule also has a structural function and creates a urinary space through which filtrate can enter the nephron and pass to the proximal convoluted tubule.
What are the three major functions of the loop of Henle?
Other functions of the loop of Henle include:
- Homeostatic mechanisms to regulate the extracellular fluid volume.
- Regulating potassium, calcium and magnesium excretion at the lowest energy costs.
- Homeostasis of the acid-base balance via bicarbonate and ammonia excretion.
- Regulating the composition of urinary protein.
How does the countercurrent system and the loop of Henle work?
COUNTERCURRENT SYSTEM and the LOOP OF HENLE 1. The Loop of Henle establishes medullary hyperosmolarity The ascending limb of the loop of Henle transports solutes (NaCl) out of the tubule lumen with little or no water, generating an hyperosmotic medullary interstitium and delivering an hyposmotic tubule fluid to the distal tubule.
How does the countercurrent mechanism operate in the kidney?
Understanding how the countercurrent mechanism operates is aided by a thought experiment in which the entire renal interstitial fluid is assumed to possess a uniform osmolarity equivalant to that of the extracellular fluid, that is 300 mOsm/L.
What is happening in the ascending loop of Henle?
What is happening in the kidney takes advantage of this. In the ascending loop of henle, ions are ACTIVELY being pumped into the interstitial space. This creates a reaaaally salty environment, like that in our balloon example.
How does the countercurrent system permit formation of a dilute urine?
The countercurrent system permits forming a dilute urine. In the absence of ADH, the hyposmotic fluid that enters the DT from the loop of Henle, continues to be diluted by transport of NaCl via NaCl (thiazide sensitive) cotransporters into DT cells and via Na channels (amiloride sensitive) along the CD.