About 10 percent about 18 l reaches the collecting ducts. This contributes to allowing the kidneys to produce dilute urine. Computer simulation of osmotic gradient without active. Reabsorption of water in the filtrate may be hormonally controlled. Transport across loop of henle thin descending limb of loop of henle. The human kidney is made up of about a million nephrons, the filtering. 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.
A loop of henle descends into the medulla, makes a hairpin turn, and returns to the cortex. 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. Main functional principal is to recover water and sodium chloride from urine. 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. Substance proximal tubule loop of henle distal tubule and. Reabsorption of sodium in the loop of henle youtube. Nephron function simplified hand drawn animation nephron structure and functionnephron physiology the nephron uses four mechanisms to convert blood into urine. The thin ascending limb of the loop of henle is distinguished from the descending limb in that the tight. Most water is recovered in the pct, loop of henle, and dct. Research career program award 6k3gm 21,786 from the national institute of. The thin descending limb of the loop of henle has leaky tight junctions. Other molecules get reabsorbed passively when they are caught up in the flow of water solvent drag. Worlds best powerpoint templates crystalgraphics offers more powerpoint templates than anyone else in the world, with over 4 million to choose from. 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.
Dec 22, 2010 ions and water molecules flow through the tubule. Ppt renal tubular reabsorption powerpoint presentation. If loop of henle was absent from the mammalian nephron. Named after its discoverer, the german anatomist friedrich gustav jakob henle, the loop of henles main function is to create a concentration. The ascending limb drains urine into the distal convoluted tubule. Here, water is reabsorbed, along with ions and other organic matter. Filtered fluid first passes through the descending limb. Water gets reabsorbed passively by osmosis in response to the buildup of reabsorbed na in spaces between the cells that form the walls of the nephron. 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.
The fluid filtered into bowmans space is an ultrafiltrate of plasma containing many vital small molecular weight solutes e. 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. Reabsorption and secretion along the loop of henle anatomy. The science of biology, ninth edition, published by sinauer associates. The reabsorption of bicarbonate must therefore occur indirectly.
The principal function of the loop of henle appears to be the recovery of water and sodium chloride from the urine. This function allows production of urine that is far more concentrated than blood. As the filtrate moves through this part of the nephron, the body fluids reabsorb lots of essential nutrients. Water reabsorbed isoosmotically and independant of adh. 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. In the descending limb, water is removed from the filtrate and enters into the interstitium, resulting in a highly concentrated filtrate. Full text the importance of the thick ascending limb of henles loop.
The thick ascending limb tal of henles loop is a crucial segment for many. 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. The removal of water serves to concentrate the na and cl in the lumen.
The loss of function of any of those proteins leads to a salt losing phenotype. Bulk of water reabsorption is secondary to sodium reabsorption. Nephron function simplified hand drawn animation youtube. Reabsorption allows many useful solutes primarily glucose and amino acids, salts and water that have passed through bowmans capsule, to return to the circulation. Using computer software to optimize treatment for diabetic kidney diseases. 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. Part 4 in a 8 part lecture on filtrate reabsorption in a flipped human physiology course taught by wendy riggs. Open aquaporin channels in collecting duct by increasing adh. Winner of the standing ovation award for best powerpoint templates from presentations magazine. The loops of cortical nephrons do not extend into the renal medulla very far, if at all.
Understanding nephron physiology and ion reabsorption ap. In summary, the loop of henle is surrounded by tissue fluid which has a high concentration of ions in it. Jan 10, 2012 the loop of henle is basically divided into two main parts, the ascending and descending limbs. Late distal tubule and collecting duct have a fractional reabsorption of h2o large part of gfr. 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. Reabsorption of most substances is related to the reabsorption of na, either directly, via.
Full article loop diuretics are diuretics that act on the ascending loop of henle in the kidney. The loop of henle serves to create a concentration gradient throughout the nephron which helps increase the reabsorption of water and certain ions. This is according to my a2 textbook btw so if ive said something wrong blame the book. Descending limb of the loop of henle human physiology. The descending limb, the thin ascending limb and the thick ascending limb. If loop of henle was absent from the mammalian nephron would. Tubular reabsorption in the loop of henle was studied during orthograde microperfusion from late proximal tubular site as previously described huang et al. Proximal and distal nephron configuration of nephrons with superficial glomeruli were identified by intratubular application of small amounts of stained artificial tubular fluid. Pages 26 ratings 100% 4 4 out of 4 people found this. That renal tubular reabsorption must occur is intuitively obvious because. The solutes only have so much osmotic potential and therefore are unable to draw the excess water from the lumen. Concentrated medullary interstitium to draw water out of loop of henle 3. 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.
Reabsorption and secretion along the loop of henle. This occurs because of the properties of the descending limb, to be discussed next, and because blood vessels. 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. Im catching up on work and im a little stuck on this part. This means that the filtrate in the loop of henle becomes more concentrated and therefore has a low water potential.
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. Adapting reabsorption to filtration has the dual function of minimizing na and. 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. The point of the loop of henle is to reduce the quantity of water in the filtrate and so reduce water loss. 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. 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. In the thin descending limb, water is very permeable and is reabsorbed due to the existing concentration gradient in the medulla. A detailed explanation of how the loop of henle helps to concentrate urine. The countercurrent mechanisms to increase water reabsorption. How does water reabsortion take place in the loop of henle. Since the ascending limb is permeable to water, but not ions, this is where water reabsorption takes place.
This allows water to leave by passive diffusion as the tubule segment enters the hypertonic renal medulla. The loop of henle contributes to the absorption of approximately 25% of filtered sodium and can be targeted by diuretic therapy. Excretion of water and sodium chloride nacl is regulated in conjunction with. 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. This produces a more concentrated filtrate because of this, ions move out of the loop in the thin ascending limb. Sodium reabsorption in thick ascending limb of henles. Takes place in the proximal tubule and descending school western university. Jan 20, 2016 basics first, loop of henle loop of henle, long ushaped portion of the tubules that conduct urine with each nephrone of kidney. First the filtrate passes through the descending limb where water leaves the filtrate and diffuses through aquaporins into. They reduce the normal hyperosmolality of the medullary interstitial fluid, reducing the effects of adh, resulting in loss of nacl and water. A multimedia instructional animation and website on antiglomerular. So, the osmolarity of the urine increases as it descends the loh. Organic acids and bases secreted here via primary active. This image shows the single cell layer making up the wall of the ascending limb of the nephron.
Okaaay, so im doing a2 biology and ive missed a couple of lesson of excretion. Basics first, loop of henle loop of henle, long ushaped portion of the tubules that conduct urine with each nephrone of kidney. 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. Sodium, chloride, and potassium are reabsorbed readily in the thick. As filtrate moves down the loop of henle, water is reabsorbed, but ions na,cl arent. Rebecca kendall of the national kidney foundation, and dr. Full article in the loop of henle there is continued reabsorption of water, sodium, chloride. Now, as the filtrate moves up the other side ascending limb, na and cl are reabsorbed, but water isnt. While the thin descending limbs of the loop of henle absorb water, but not na. 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.
Retains water in body increase water reabsorption plasma osmolality and adh. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Loop of henle is long, ushaped portion of the tubule that conducts urine within each nephron of the kidney of reptiles, birds, and mammals. The principal function of the loop of henle appears to be the recovery of water. Loop of henle definition of loop of henle by merriamwebster. Its main function is to reabsorb water and sodium chloride from the filtrate. In a previous study, we described a new method 3 to measure na reabsorption by each segment of the human nephron independently. 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. 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. Sodium ions are secreted into the filtrate of the proximal convoluted tubule. I dont understand the loop of henle and what it does. The loop of henle is basically divided into two main parts, the ascending and descending limbs. Juxtamedullary nephrons have loops that extend variable distances, some very deep into the medulla.
Integrated control of na transport along the nephron ncbi. The concentration gradient created by the loop of henle is maintained by the vasa recta producing a. The main function of this structure is to create a concentration gradient in. 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. 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. This part of the renal tubule is divided into a thin and thick ascending limb. 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. Loop of henle, long, ushaped portion of the tubule that conducts urine within each nephron q. What part of the nephron is responsible for the reabsorption. The next site of water reabsorption is in the loop of henle.
The loop of henle is shaped like a u, with a descending limb and an ascending limb. Mar 19, 2015 part 4 in a 8 part lecture on filtrate reabsorption in a flipped human physiology course taught by wendy riggs. 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. From the bowmans capsule, the filtrate travels through another series of tubules. The loop of henle has a hairpin configuration with a thin descending limb and both a thin and thick. Reabsorption of bicarbonate in the proximal tubule human. 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. Sodium reabsorption in thick ascending limb of henles loop. The distal convoluted tubule receives fluid from the loop of henle. Water is drawn out of the tubule by osmosis due to the high concentration of ions in the surrounding tissue. 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. This causes water to move out of the descending limb by osmosis. The absorption of water within the descending limb leads to an increasing.
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. Water reabsorption is coupled with sodium reabsorption. Nov 23, 2010 65% water reabsorption takes place in pct. 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. 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. 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. The loop of henle has a descending limb and an ascending limb. Theyll give your presentations a professional, memorable appearance the kind of sophisticated look that todays audiences expect.