Physiological role of the loop of henle in urinary concentration. The ascending limb of the loop of henle is a direct continuation from the descending limb of loop of henle, and one of the structures in the nephron of the kidney. In the descending limb, only water is reabsorbed into the renal medulla and blood vasa. Feb 27, 2019 the human kidney is made up of about a million nephrons, the filtering units of this complex and highly vascular organ. The length of the loop is directly related to the concentration of urine and operates as a countercurrent multiplier system. Mar 28, 2018 a stepwise gradient of salts is built inside the medulla tissue by the loop of henle. In order for urea to function in this role each of the tubu. What is flowing in the opposite direction to the glomerular filtrate for it to be called countercurrent can you please explain the countercurrent multiplier mechanism in the loop of henle in the nephron, including details about the ascending limb, descending limb and the collecting duct. Filtrate passing down the descending limb of the loop of henle is flowing in the opposite direction to fluid in the ascending limb. Countercurrent multiplication in the kidneys is the process of using energy to. Apr 07, 2016 learn about how the loop of henle develops a concentration of 1200 mosml in the medulla of the kidney via a mechanism called countercurrent multiplication, or countercurrent exchange. Physiological role of the loop of henle in urinary.
Learning objectives at the end of this lecture, you will be able to. This system results in a gradually increasing concentration of renal interstitial fluid from the cortex to the inner medulla. Osmosis is a challenging topic for students with many students holding misconceptions about the process 1. Describe the transport properties of the loop of henle and. The mechanisms shown here are traditionally called the countercurrent multiplier and the countercurrent exchanger. Jul 31, 2009 the counter current multiplier system. The loop of henle is a section of the nephron that leads from the proximal convoluted tubule to the distal convoluted tubule in the kidney. Each nephron is composed of a highly coiled tubule, one end of which forms a. Summary of the countercurrent mechanism the primary engineis active salt reabsorption without water by the thick ascending limb of henles loop. Water levels and the kidney scool, the revision website. Mimi lam, professor at case western reserve university school of medicine, explains the countercurrent multiplier. The length of the loop is directly related to the concentration of urine and operates as a. Loop of henle and distal nephron flashcards quizlet.
Transport of nacl without water in the thin and thick ascending limb of the loop of henle results in an interstitial osmolal gradient from 285 mosmolkg in the cortex, similar to plasma to 1200 mosmolkg in the medulla at the tip of the renal. The principal function of the loop of henle appears to be the recovery of water and sodium chloride from the urine. The main function of this structure is to reabsorb water and ions from the urine. If youre seeing this message, it means were having trouble loading external resources on our website. The aims of the loop of henle is to reduce the volume of water and solutes within the urine but without changing the concentration. Terms in this set 9 the countercurrent arrangement of the two limbs of the loop of henle becomes a multiplier of electrolyte concentration due to which other characteristic.
Countercurrent multiplication system without active transport. Incomplete loop of henle in birds student doctor network. Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Lecture 35 loop of henle countercurrent multiplier. Animals in arid climates have very long loops of henle and produce small quantities of highly concentrated urine. Using a classic paper by gottschalk and mylle to teach the. The loop of henle acts as a countercurrent multiplier see figure 355 and as such creates a medullary interstitial osmolar gradient. Reabsorption and secretion along the loop of henle anatomy. Countercurrent multiplier system and loop of henle. Loop of henle 1002 800 alh 400 402 200 dlh the countercurrent multiplier cortex medulla h 2o 1200 285 100 502 802 1100 1102 500 300 900 800 600 salt. Study 45 terms countercurrent exchange system flashcards.
The loop of henle generates an osmotic concentration gradient in its adjoining fluid, hereby allowing urine production which is more osmotically concentrated than blood plasma. The loop of henle, however, is incompletely developed or absent in many nephrons of the bird kidney sperber, i960, and although many species appear able to produce a hypertonic urine the concentrating capacity of the kidney is considerably less than that of the mammal. The countercurrent flowarrangement of henles loop and the vasa recta traps salt and urea within the medulla and minimizes the volume of water entering the medullary interstitium. Little attention was paid to the loop of henle in smiths book, largely due to the lack of any knowledge of its function, and schematic diagrams of the nephron depicted the loop of henle as if it. A detailed explanation of how the loop of henle helps to concentrate urine using the countercurrent multiplication mechanism. The ascending limb drains urine into the distal convoluted tubule. Describe the counter current multiplier system in the loop of. He explains that the mechanism by which mammalian kidneys produce a. An animation to explain the kidneys role in balancing h2o and electrolytes by creating a concentration gradient in the nephrons. The other part of the solution, and the reason that the loop of henle is in fact a loop lies in the principle of countercurrent multiplication. The loop of henles main function is to create a concentration gradient in the medulla of the kidney. Learn about how the loop of henle develops a concentration of 1200 mosml in the medulla of the kidney via a mechanism called countercurrent multiplication, or countercurrent exchange. The entire process that i have just described is called countercurrent multiplication. The loop of henle is supplied by blood in a series of straight capillaries descending from the cortical efferent arterioles.
The flowing bodies can be liquids, gases, or even solid powders, or any combination of those. Counter current mechanism concentrated urine formation byjus. Usmle is a joint program of the federation of state medical. In a countercurrent multiplier, the combined action of active pumping and circulation and recirculation of solutes around the loop of henle create an osmotic gradient with the following properties. Its primary function is reabsorption of nacl and water. The countercurrent multiplier system recirculates salt and thus traps some of the salt that enters the loop of henle in the interstitial fluid of the renal medulla. Learn about how the loop of henle develops a concentration of 1200 mosml in the medulla of the kidney via a mechanism called. Countercurrent mechanisms the mechanisms shown here are traditionally called the countercurrent multiplier and the countercurrent exchanger. The first takes place in the region of the nephron called henle s loop. The loop of henle is a part of a nephron, a tiny tube inside the kidneys that filters solutes. Each kidney contains hundreds of thousands of individual nephrons, which pass between the cortex of the kidneys and the medulla, connecting to collecting ducts which route urine to the ureter so that it can be expressed.
Loop of henle definition of loop of henle by medical. The theory of counter current multiplication states that if the transport processes in the loop of henle could produce a small osmotic gradient at any horizontal level between the descending and ascending limbs, this could be multiplied into a large longitudinal gradient by the counter current arrangement flow in opposite directions in the. According to this hypothesis, the ioops of henle serve as a countercurrent multiplier system to generate and maintain a medullary osmotic gradient which increases from the cortex to the tip of the papilla. The mechanism that the kidneys use to concentrate urine is called the. If youre behind a web filter, please make sure that the domains. Its primary function uses a countercurrent mechanism in the medulla to reabsorb water and ions from the urine. Describe the counter current multiplier system in the loop. The countercurrent mechanism partially contributes to generation of the corticopapillary osmotic gradient and is the product of juxtamedullary nephrons which possess long loops of henle that extend far into the renal medulla. Countercurrent exchange is a mechanism occurring in nature and mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some chemical, between two flowing bodies flowing in opposite directions to each other. The loop of henle is found in the medulla of the kidney.
These nephrons perform the major function of the kidney, which is to clear harmful substances from the body by filtering the blood. Transport of nacl without water in the thin and thick ascending limb of the loop of henle results in an interstitial osmolal gradient from 285 mosmolkg in the cortex, similar to plasma to 1200 mosmolkg in the medulla at the tip of the renal papilla. Why is the countercurrent multiplier called like that. Kidney function counter current mechanism animation youtube. A conceptual model of the countercurrent multiplication mechanism, now so. 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. This research was supported by usphs program grant. The mechanism of action increases the excretion of sodium, water, chloride, magnesium, potassium, and bicarbonate, thereby promoting diuresis skidmoreroth, 2008. The loop of henle is a specific portion of the nephron that is partially located in the renal cortex, and partly located in the renal medulla. Countercurrent multiplication in the kidney video khan. The fluid is increasingly concentrated as it moves down and increasingly dilute as it moves up.
The counter current multiplier in the loop of henle the kidney regulates the internal environment by judicious excretion of watersoluble plasma constituents and water. This part of the renal tubule is divided into a thin and thick ascending limb. In the descending limb, only water is reabsorbed into the renal medulla and blood vasa recta. Loop of henle definition of loop of henle by medical dictionary. Write what is loop of henle and its function science. The loop of henle is found between the proximal convoluted tubule and the distal convoluted tubule in the nephron. The countercurrent multiplier of the loop of henle is a challenging process to teach. Khan academy is a nonprofit with the mission of providing a free. Fluid entering the loop of henle is isotonic osmolarity 300 mosml but the volume is only a third of the volume originally filtered into bowmans capsule.
Physiological principles edit the term derives from the form and function of the loop of henle, which consists of two parallel limbs of renal tubules running in opposite. This function allows production of urine that is far more concentrated than blood. In a countercurrent multiplier, the combined action of active pumping and circulation and recirculation of solutes around the loop of henle create an. Demystifying the countercurrent multiplier youtube. To do this, it uses a countercurrent multiplier mechanism in the medulla. The countercurrent multiplier system uses the salt reabsorbed from the ascending limb of the loop of henle to lay down salts there. Experimental validation of the countercurrent model of urinary. Initially the countercurrent exchange mechanism and its properties were proposed in 1951 by professor werner kuhn and two of his former students who called the mechanism found in the loop of henle in mammalian kidneys a countercurrent multiplier and confirmed by laboratory findings in 1958 by professor carl w. In the presence of antidiuretic hormone adh, the isosmotic fluid which enters the medullary collecting duct achieves osmotic equilibration. It also excretes waste products, the most notable being urea. There are actually two types of nephron in the kidney cortical and juxtamedullary.
The loop is an important part of the whole system, as it. Introduction the countercurrent multiplier theory of the. Sodium and chloride ions are actively pumped from the ascending limb of the loop but water is retained, since the ascending limb is impermeable to water. In doing this it creates a hypertonic medulla it does this by using a countercurrent multiplier. Sodium and chloride ions are actively pumped from the ascending limb of the loop but water is retained, since the ascending limb is impermeable. Countercurrent multiplication is frequently mistaken for countercurrent exchange, a similar but different mechanism where gradients are maintained, but not established. Within the nephron of the kidney, the ascending limb of the loop of henle is a segment of the heterogenous loop of henle downstream of the descending limb, after the sharp bend of the loop. The thin descending limb is passively permeable to both water and small solutes such as sodium chloride and urea. The presence of loop of henle enables birds and mammals including man to produce urine which is hypertonic to the blood. Jul 01, 2008 the loop has a hairpin bend in the renal medulla. Chlorothiazide is a sulfonamide loop diuretic that acts on the distal tubule and thick ascending limb of the loop of henle.
The extrusion of sodium chloride from the ascending limb makes the surrounding interstitial fluid more. Information and translations of loop of henle in the most comprehensive dictionary definitions resource on the web. This countercurrent flow or countercurrent multiplier allows concentrated urine to be produced. Urea is produced in the liver and contains the nitrogen derived from amino acids or proteins. The three segments of the loops of henle have different characteristics that enable countercurrent multiplication. The loop of henle encompasses the thin descending limb, the thin ascending limb, and the tal. Loop of henle, long, ushaped portion of the tubule that conducts urine within each nephron q. Countercurrent multiplication in the loop of henle youtube. Khan academy is a nonprofit with the mission of providing a free, worldclass education for anyone, anywhere. Through the countercurrent multiplier effect, a hypertonic medulla is created allowing reabsorption of water from the collecting duct and the descending limb via osmosis.
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