I know that water moves out of the descending loop of henle via osmosis and is carried away by the vasa recta which helps to maintain the concentration gradient i. Nov 21, 2009 in the descending limb of the loop of henle, sodium and chloride ions diffuse into the limb, whilst water moves out by osmosis and enters the capillaries. As the filtrate moves through this part of the nephron, the body fluids reabsorb lots of essential nutrients. The reabsorption of bicarbonate must therefore occur indirectly. Sodium reabsorption in thick ascending limb of henles loop. Mar, 2016 sodium is reabsorbed through the thick ascending limb of the loop of henle, through the nak2cl cotransporter on the apical membrane, and via the nak atpase on the basolateral side. The concentration gradient created by the loop of henle is maintained by the vasa recta producing a countercurrent exchange mechanism. The fluid filtered into bowmans space is an ultrafiltrate of plasma containing many vital small molecular weight solutes e. The human kidney is made up of about a million nephrons, the filtering. Loop of henle definition of loop of henle by merriamwebster. The thin descending limb of the loop of henle has leaky tight junctions.
From the bowmans capsule, the filtrate travels through another series of tubules. But reabsorption of water from the collecting tubule is facultative because it is under control of the hormone adh see below. Can you give me a clear definition of the loop of henle. Adapting reabsorption to filtration has the dual function of minimizing na and. The principal function of the loop of henle appears to be the recovery of water and sodium chloride from the urine. I dont understand the loop of henle and what it does. The descending limb, the thin ascending limb and the thick ascending limb. The thick ascending limb tal of henles loop is a crucial segment for many. Named after its discoverer, the german anatomist friedrich gustav jakob henle, the loop of henles main function is to create a concentration. The loop of henle has a descending limb and an ascending limb.
In order to reach this high a concentration, the salt pumped out of the ascending limb must accumulate in the interstitial fluid of the medulla. Reabsorption allows many useful solutes primarily glucose and amino acids, salts and water that have passed through bowmans capsule, to return to the circulation. Jan 10, 2012 the loop of henle is basically divided into two main parts, the ascending and descending limbs. The ascending limb drains urine into the distal convoluted tubule. The loss of function of any of those proteins leads to a salt losing phenotype. The inhibition of renal carbonic anhydrase causes the loss of bicarbonate and water in the urine, producing a metabolic acidosis and diuresis that help to alleviate the symptoms. This part of the renal tubule is divided into a thin and thick ascending limb. They reduce the normal hyperosmolality of the medullary interstitial fluid, reducing the effects of adh, resulting in loss of nacl and water. When there is excess water in the body, the excess fluid passes through the loop of henle because the fluid entering the loop is less concentrated already. The distal convoluted tubule receives fluid from the loop of henle. Since the ascending limb is permeable to water, but not ions, this is where water reabsorption takes place. A loop of henle descends into the medulla, makes a hairpin turn, and returns to the cortex. Filtered fluid first passes through the descending limb.
Here, water flows out of the tubule into the surrounding tissue, as the walls of the nephron are permeable to water in this part of the structure. Descending limb of the loop of henle human physiology. Reabsorption and secretion along the loop of henle anatomy. The thin ascending limb of the loop of henle is distinguished from the descending limb in that the tight junctions are now tight and water impermeable. Understanding nephron physiology and ion reabsorption ap. In the kidney, the loop of henle is the portion of the nephron that leads from the proximal convoluted tubule to the distal convoluted tubule. 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. Worlds best powerpoint templates crystalgraphics offers more powerpoint templates than anyone else in the world, with over 4 million to choose from. Reabsorption of water in the filtrate may be hormonally controlled. Reabsorption was expressed as equivalent volumes of solutefree water ch2o generated by the loop of henle ch2ohl and by the distal tubule ch2odt, and dissipated by back diffusion bd across collecting ducts. A multimedia instructional animation and website on antiglomerular. How does water reabsortion take place in the loop of henle. Full text the importance of the thick ascending limb of henles loop. This function allows production of urine that is far more concentrated than blood.
The deeper regions of the medulla, around the tips of the loops of juxtamedullary nephrons, reach a concentration of 1,200 to 1,400 mosm. In the descending limb, water is removed from the filtrate and enters into the interstitium, resulting in a highly concentrated filtrate. Research career program award 6k3gm 21,786 from the national institute of. Other molecules get reabsorbed passively when they are caught up in the flow of water solvent drag. Theyll give your presentations a professional, memorable appearance the kind of sophisticated look that todays audiences expect. What part of the nephron is responsible for the reabsorption. Rebecca kendall of the national kidney foundation, and dr. Reabsorption and secretion along the loop of henle. Water abstraction along the early part of the thin descending limb tdl is driven by the high osmolarity at least half due to urea present in the medullary interstitium. Retains water in body increase water reabsorption plasma osmolality and adh. The solutes only have so much osmotic potential and therefore are unable to draw the excess water from the lumen. About 10 percent about 18 l reaches the collecting ducts. Nephron function simplified hand drawn animation nephron structure and functionnephron physiology the nephron uses four mechanisms to convert blood into urine.
As plasma osmolarity increases more concentrated, adh increases to retain more water. Ion transport along the nephron is essential for the reabsorption of sodium and water, maintenance of plasma volume and blood pressure and production of urine. This is according to my a2 textbook btw so if ive said something wrong blame the book. Takes place in the proximal tubule and descending school western university. In the descending limb of the loop of henle, sodium and chloride ions diffuse into the limb, whilst water moves out by osmosis and enters the capillaries. While the thin descending limbs of the loop of henle absorb water, but not na. Using computer software to optimize treatment for diabetic kidney diseases. The collecting ducts, under the influence of adh, can recover almost all of the water passing through them, in cases of dehydration, or almost none of the water, in cases of overhydration. Reabsorption of bicarbonate in the proximal tubule human.
The principal function of the loop of henle appears to be the recovery of water. Tubular reabsorption in the loop of henle was studied during orthograde microperfusion from late proximal tubular site as previously described huang et al. If loop of henle was absent from the mammalian nephron. This occurs because of the properties of the descending limb, to be discussed next, and because blood vessels. This allows water to leave by passive diffusion as the tubule segment enters the hypertonic renal medulla. As filtrate moves down the loop of henle, water is reabsorbed, but ions na,cl arent. Winner of the standing ovation award for best powerpoint templates from presentations magazine. Nephrology physiology reabsorption and secretion duration. This image shows the single cell layer making up the wall of the ascending limb of the nephron. These solutes are reabsorbed isotonically, in that the osmotic potential of the fluid leaving the proximal convoluted tubule is the same as that of the initial glomerular filtrate. Countercurrent multiplier system and loop of henle water reabsorption occurs via osmosis requires hypertonic interstitial fluid problem.
Integrated control of na transport along the nephron ncbi. The removal of water serves to concentrate the na and cl in the lumen. Sodium is reabsorbed through the thick ascending limb of the loop of henle, through the nak2cl cotransporter on the apical membrane, and via the nak atpase on the basolateral side. The point of the loop of henle is to reduce the quantity of water in the filtrate and so reduce water loss. As the name suggests, at the transition from descending to ascending, the tubule segment makes a 180degree turn and the filtrate is now being carried back toward the cortex. Nov 23, 2010 65% water reabsorption takes place in pct. Sodium reabsorption in thick ascending limb of henles. Okaaay, so im doing a2 biology and ive missed a couple of lesson of excretion.
In a previous study, we described a new method 3 to measure na reabsorption by each segment of the human nephron independently. Here, water is reabsorbed, along with ions and other organic matter. Nephron function simplified hand drawn animation youtube. Transport across loop of henle thin descending limb of loop of henle. Full article loop diuretics are diuretics that act on the ascending loop of henle in the kidney. This produces a more concentrated filtrate because of this, ions move out of the loop in the thin ascending limb. The loop of henle contributes to the absorption of approximately 25% of filtered sodium and can be targeted by diuretic therapy. The absorption of water within the descending limb leads to an increasing. Now, as the filtrate moves up the other side ascending limb, na and cl are reabsorbed, but water isnt. The main function of this structure is to create a concentration gradient in. The loop of henle has a hairpin configuration with a thin descending limb and both a thin and thick.
So, the osmolarity of the urine increases as it descends the loh. The science of biology, ninth edition, published by sinauer associates. Excretion of water and sodium chloride nacl is regulated in conjunction with. If loop of henle was absent from the mammalian nephron would. Water reabsorption is coupled with sodium reabsorption. The countercurrent mechanisms to increase water reabsorption. Full article in the loop of henle there is continued reabsorption of water, sodium, chloride. The next site of water reabsorption is in the loop of henle. Loop of henle definition is the ushaped part of the nephron of birds and mammals that lies between and is continuous with the proximal and distal convoluted tubules and that functions in water resorption. The interstitium of the kidney increases in osmolarity outside as the loop of henle descends from 600 mosml in the outer medulla of the kidney to 1200 mosml in the inner medulla.
First the filtrate passes through the descending limb where water leaves the filtrate and diffuses through aquaporins into. Hormonal regulation of solute and water transport critical proximal tubule does vary h2o reabsorption, but only slightly ability to vary may become important in conditions of water conservatio. The loops of cortical nephrons do not extend into the renal medulla very far, if at all. In summary, the loop of henle is surrounded by tissue fluid which has a high concentration of ions in it.
Loop of henle is long, ushaped portion of the tubule that conducts urine within each nephron of the kidney of reptiles, birds, and mammals. Reabsorption of sodium in the loop of henle youtube. Calcium bulk reabsorption but not regulation of calcium occurs in the proximal tubule calcium can passively move paracellulary into the vasa recta the regulation of how much calcium is reabsorbed occurs in the distal tubule and collecting ducts. Reabsorption of most substances is related to the reabsorption of na, either directly, via.
The loop of henle is shaped like a u, with a descending limb and an ascending limb. Part 4 in a 8 part lecture on filtrate reabsorption in a flipped human physiology course taught by wendy riggs. Loop of henle, long, ushaped portion of the tubule that conducts urine within each nephron q. Im catching up on work and im a little stuck on this part. Sodium ions are secreted into the filtrate of the proximal convoluted tubule. Concentrated medullary interstitium to draw water out of loop of henle 3. Since water is also reabsorbed the volume of fluid in the loop of henle is less than the pct, approximately onethird of the original volume. Juxtamedullary nephrons have loops that extend variable distances, some very deep into the medulla. Open aquaporin channels in collecting duct by increasing adh.
Jul 04, 2007 loop of henle is long, ushaped portion of the tubule that conducts urine within each nephron of the kidney of reptiles, birds, and mammals. This contributes to allowing the kidneys to produce dilute urine. That renal tubular reabsorption must occur is intuitively obvious because. In the thin descending limb, water is very permeable and is reabsorbed due to the existing concentration gradient in the medulla. The concentration gradient created by the loop of henle is maintained by the vasa recta producing a. In the deep nephrons, water reabsorption increases the tubule fluid osmolarity up to 1200 mosml and the na concentration up to 300 meql by the bend of the loop. 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. Learn vocabulary, terms, and more with flashcards, games, and other study tools.
This means that the filtrate in the loop of henle becomes more concentrated and therefore has a low water potential. 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. Main functional principal is to recover water and sodium chloride from urine. Bulk of water reabsorption is secondary to sodium reabsorption. Mar 19, 2015 part 4 in a 8 part lecture on filtrate reabsorption in a flipped human physiology course taught by wendy riggs.
Copyright 2020 dove press ltd software development by. A detailed explanation of how the loop of henle helps to concentrate urine. Computer simulation of osmotic gradient without active. The loop of henle serves to create a concentration gradient throughout the nephron which helps increase the reabsorption of water and certain ions. Water is drawn out of the tubule by osmosis due to the high concentration of ions in the surrounding tissue. Basics first, loop of henle loop of henle, long ushaped portion of the tubules that conduct urine with each nephrone of kidney. Substance proximal tubule loop of henle distal tubule and. Organic acids and bases secreted here via primary active. The thin ascending limb of the loop of henle is distinguished from the descending limb in that the tight. Sodium, chloride, and potassium are reabsorbed readily in the thick. Pages 26 ratings 100% 4 4 out of 4 people found this. The loop of henle is basically divided into two main parts, the ascending and descending limbs.
Its main function is to reabsorb water and sodium chloride from the filtrate. Proximal and distal nephron configuration of nephrons with superficial glomeruli were identified by intratubular application of small amounts of stained artificial tubular fluid. 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. Ppt renal tubular reabsorption powerpoint presentation. This causes water to move out of the descending limb by osmosis. The loop of henle serves the crucial function of creating an ion gradient in the renal medulla by fluctuating the reabsorption of water and ions. Late distal tubule and collecting duct have a fractional reabsorption of h2o large part of gfr. Dec 22, 2010 ions and water molecules flow through the tubule.