742:). This acts as a counter-current exchange system which short-circuits the warmth from the arterial blood directly into the venous blood returning into the trunk, causing minimal heat loss from the extremities in cold weather. The subcutaneous limb veins are tightly constricted, thereby reducing heat loss via this route, and forcing the blood returning from the extremities into the counter-current blood flow systems in the centers of the limbs. Birds and mammals that regularly immerse their limbs in cold or icy water have particularly well developed counter-current blood flow systems to their limbs, allowing prolonged exposure of the extremities to the cold without significant loss of body heat, even when the limbs are as thin as the
769:, or venae comitantes, that run through the blubber from their minimally insulated limbs and thin streamlined protuberances. Each plexus consists of a central artery containing warm blood from the heart surrounded by a bundle of veins containing cool blood from the body surface. As these fluids flow past each other, they create a heat gradient in which heat is transferred and retained inside the body. The warm arterial blood transfers most of its heat to the cool venous blood now coming in from the outside. This conserves heat by recirculating it back to the body core. Since the arteries give up a good deal of their heat in this exchange, there is less heat lost through
268:
849:
525:
343:
122:
145:(usually temperature or concentration difference). In cocurrent exchange the initial gradient is higher but falls off quickly, leading to wasted potential. For example, in the adjacent diagram, the fluid being heated (exiting top) has a higher exiting temperature than the cooled fluid (exiting bottom) that was used for heating. With cocurrent or parallel exchange the heated and cooled fluids can only approach one another. The result is that countercurrent exchange can achieve a greater amount of heat or mass transfer than parallel under otherwise similar conditions.
378:
close to 60 °C. Because the hot input is at its maximum temperature of 60 °C, and the exiting water at the bottom pipe is nearly at that temperature but not quite, the water in the top pipe can warm the one in the bottom pipe to nearly its own temperature. At the cold end—the water exit from the top pipe, because the cold water entering the bottom pipe is still cold at 20 °C, it can extract the last of the heat from the now-cooled hot water in the top pipe, bringing its temperature down nearly to the level of the cold input fluid (21 °C).
2033:
330:. Many of the water molecules pass from the freshwater flow in order to dilute the brine, while the concentration of salt in the freshwater constantly grows (since the salt is not leaving this flow, while water is). This will continue, until both flows reach a similar dilution, with a concentration somewhere close to midway between the two original dilutions. Once that happens, there will be no more flow between the two tubes, since both are at a similar dilution and there is no more
415:
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462:
958:
25:
222:
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difference of 40 °C and much heat transfer; at the output end, there is a very small temperature difference (both are at the same temperature of 40 °C or close to it), and very little heat transfer if any at all. If the equilibrium—where both tubes are at the same temperature—is reached before the exit of the liquid from the tubes, no further heat transfer will be achieved along the remaining length of the tubes.
781:
snow. As the (cold) blood flows back up from the paws through the veins, it picks up heat from the blood flowing in the opposite direction, so that it returns to the torso in a warm state, allowing the fox to maintain a comfortable temperature, without losing it to the snow. This system is so efficient that the Arctic fox does not begin to shiver until the temperature drops to −70 °C (−94 °F).
982:
881:
297:
670:: The collecting duct receives liquid between 100 mOsm if no re-absorption is done, to 300 or above if re-absorption was used. The collecting duct may continue raising the concentration if required, by gradually pumping out the same ions as the Distal convoluted tubule, using the same gradient as the ascending limbs in the loop of Henle, and reaching the same concentration.
533:
605:
For example, the liquid at one section inside the thin descending limb is at 400 mOsm while outside it is 401. Further down the descending limb, the inside concentration is 500 while outside it is 501, so a constant difference of 1 mOsm is kept all across the membrane, although the concentration
511:
The tip of the loop has the highest concentration of salt (NaCl) in the incoming tube—in the example 1199 mg/L, and in the buffer 1200 mg/L. The returning tube has active transport pumps, pumping salt out to the buffer liquid at a low difference of concentrations of up to 200 mg/L more
283:
As the cocurrent and countercurrent exchange mechanisms diagram showed, a cocurrent exchange system has a variable gradient over the length of the exchanger. With equal flows in the two tubes, this method of exchange is only capable of moving half of the property from one flow to the other, no matter
275:
is depicted by the upper and lower diagrams respectively. In both it is assumed (and indicated) that red has a higher value (e.g. of temperature) than blue and that the property being transported in the channels therefore flows from red to blue. Note that channels are contiguous if effective exchange
515:
In effect, this can be seen as a gradually multiplying effect—hence the name of the phenomena: a 'countercurrent multiplier' or the mechanism: Countercurrent multiplication, but in current engineering terms, countercurrent multiplication is any process where only slight pumping is needed, due to the
469:
A countercurrent multiplication loop is a system where fluid flows in a loop so that the entrance and exit are at similar low concentration of a dissolved substance but at the far end of the loop there is a high concentration of that substance. A buffer liquid between the incoming and outgoing tubes
377:
In this example, hot water at 60 °C enters the top pipe. It warms water in the bottom pipe which has been warmed up along the way, to almost 60 °C. A minute but existing heat difference still exists, and a small amount of heat is transferred, so that the water leaving the bottom pipe is at
133:
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 flowing bodies can be liquids, gases, or even solid powders, or any
1372:
published with remarks by
Professor Bart Hargitay, then one of the two former student aids. Harbitay says: Before settling in Basel, Kuhn did some very fundamental work in Kiel, separating isotopes in a centrifuge. This caused him to be fascinated with the effect of countercurrents in multiplying a
867:
of chemicals such as in petroleum refining is done in towers or columns with perforated trays. Vapor from the low boiling fractions bubbles upward through the holes in the trays in contact with the down flowing high boiling fractions. The concentration of low boiling fraction increases in each tray
859:
is a method of separation, that is based on the differential partitioning of analytes between two immiscible liquids using countercurrent or cocurrent flow. Evolving from Craig's
Countercurrent Distribution (CCD), the most widely used term and abbreviation is CounterCurrent Chromatography (CCC), in
353:
Two tubes have a liquid flowing in opposite directions, transferring a property from one tube to the other. For example, this could be transferring heat from a hot flow of liquid to a cold one, or transferring the concentration of a dissolved solute from a high concentration flow of liquid to a low
212:
is a similar but different concept where liquid moves in a loop followed by a long length of movement in opposite directions with an intermediate zone. The tube leading to the loop passively building up a gradient of heat (or cooling) or solvent concentration while the returning tube has a constant
824:
a. A salt extraction system with a countercurrent multiplication mechanism, where salt is actively pumped from the blood 'venules' (small veins) into the gland tubules. Although the fluid in the tubules is with a higher concentration of salt than the blood, the flow is arranged in a countercurrent
780:
treading on snow. The paws are necessarily cold, but blood can circulate to bring nutrients to the paws without losing much heat from the body. Proximity of arteries and veins in the leg results in heat exchange, so that as the blood flows down it becomes cooler, and does not lose much heat to the
732:
The arterial and deep vein blood supply to the human arm. The superficial (subcutaneous) veins are not shown. The deep veins are wrapped round the arteries, and the consequent counter-current flow allows the hand to be cooled down considerably without loss of body heat, which is short-circuited by
793:
near the nostrils which concentrates brine, later to be "sneezed" out to the sea, in effect allowing these birds to drink seawater without the need to find freshwater resources. It also enables the seabirds to remove the excess salt entering the body when eating, swimming or diving in the sea for
507:
O). Further up the loop there is a continued flow of water out of the tube and into the buffer, gradually raising the concentration of NaCl in the tube until it reaches 1199 mg/L at the tip. The buffer liquid between the two tubes is at a gradually rising concentration, always a bit over the
314:
The hot fluid heats the cold one, and the cold fluid cools down the warm one. The result is thermal equilibrium: Both fluids end up at around the same temperature: 40 °C, almost exactly between the two original temperatures (20 and 60 °C). At the input end, there is a large temperature
638:
For example, the pumps at a section close to the bend, pump out from 1000 mOsm inside the ascending limb to 1200 mOsm outside it, with a 200 mOsm across. Pumps further up the thin ascending limb, pump out from 400 mOsm into liquid at 600 mOsm, so again the difference is
361:
between the two flows over their entire length of contact. With a sufficiently long length and a sufficiently low flow rate this can result in almost all of the property transferred. So, for example, in the case of heat exchange, the exiting liquid will be almost as hot as the original incoming
405:
and the mass flow rate must be the same for each stream. If the two flows are not equal, for example if heat is being transferred from water to air or vice versa, then, similar to cocurrent exchange systems, a variation in the gradient is expected because of a buildup of the property not being
287:
If each stream changes its property to be 50% closer to that of the opposite stream's inlet condition, exchange will stop when the point of equilibrium is reached, and the gradient has declined to zero. In the case of unequal flows, the equilibrium condition will occur somewhat closer to the
600:: The liquid passes from the thin descending limb to the thick ascending limb. Water is constantly released via osmosis. Gradually there is a buildup of osmotic concentration, until 1200 mOsm is reached at the loop tip, but the difference across the membrane is kept small and constant.
512:
than in the tube. Thus when opposite the 1000 mg/L in the buffer liquid, the concentration in the tube is 800 and only 200 mg/L are needed to be pumped out. But the same is true anywhere along the line, so that at exit of the loop also only 200 mg/L need to be pumped.
825:
exchange, so that the blood with a high concentration of salt enters the system close to where the gland tubules exit and connect to the main canal. Thus, all along the gland, there is only a small gradient to climb, in order to push the salt from the blood to the salty fluid with
169:
Other countercurrent exchange circuits where the incoming and outgoing fluids touch each other are used for retaining a high concentration of a dissolved substance or for retaining heat, or for allowing the external buildup of the heat or concentration at one point in the system.
157:
Countercurrent exchange when set up in a circuit or loop can be used for building up concentrations, heat, or other properties of flowing liquids. Specifically when set up in a loop with a buffering liquid between the incoming and outgoing fluid running in a circuit, and with
1020:
977:. The kiln is built in stages, where fresh air coming to the fuel is passed downwards while the smoke and heat is pushed up and out. The heat does not leave the kiln, but is transferred back to the incoming air, and thus slowly builds up to 3000 °C and more.
473:
The system allows the buildup of a high concentration gradually, by allowing a natural buildup of concentration towards the tip inside the in-going tube, (for example using osmosis of water out of the input pipe and into the buffer fluid), and the use of many
716:, a considerable contemporary authority on renal physiology, opposed the model countercurrent concentration for 8 years, until conceding ground in 1959. Ever since, many similar mechanisms have been found in biologic systems, the most notable of these: the
895:(also called 'solvent extraction' or 'partitioning') is a common method for extracting a substance from one liquid into another liquid at a different 'phase' (such as "slurry"). This method, which implements a countercurrent mechanism, is used in
381:
The result is that the top pipe which received hot water, now has cold water leaving it at 20 °C, while the bottom pipe which received cold water, is now emitting hot water at close to 60 °C. In effect, most of the heat was transferred.
993:
may be created using a countercurrent kiln where the heat is passed in the cement and the exhaust combined, while the incoming air draft is passed along the two, absorbing the heat and retaining it inside the furnace, finally reaching high
213:
small pumping action all along it, so that a gradual intensification of the heat or concentration is created towards the loop. Countercurrent multiplication has been found in the kidneys as well as in many other biological organs.
125:
Counter heat current exchange: Note the gradually declining differential and that the once hot and cold streams exit with a reversed temperature difference; the hotter entering stream becomes the exiting cooler stream and vice
558:(tubules carrying liquid in the process of gradually concentrating the urea). The active transport pumps need only to overcome a constant and low gradient of concentration, because of the countercurrent multiplier mechanism.
820:
In seabirds the salt gland is above the beak, leading to a main canal above the beak, and water is blown from two small nostrils on the beak, to empty it. The salt gland has two countercurrent mechanisms working in it:
516:
constant small difference of concentration or heat along the process, gradually raising to its maximum. There is no need for a buffer liquid, if the desired effect is receiving a high concentration at the output pipe.
310:
Two tubes have a liquid flowing in the same direction. One starts off hot at 60 °C, the second cold at 20 °C. A thermoconductive membrane or an open section allows heat transfer between the two flows.
737:
In cold weather the blood flow to the limbs of birds and mammals is reduced on exposure to cold environmental conditions, and returned to the trunk via the deep veins which lie alongside the arteries (forming
836:
b. The blood supply system to the gland is set in countercurrent exchange loop mechanism for keeping the high concentration of salt in the gland's blood, so that it does not leave back to the blood system.
1015:
In nuclear power plants, water leaving the plant must not contain even trace particles of
Uranium. Counter Current Decantation (CCD) is used in some facilities to extract water, totally clear of Uranium.
141:
The maximum amount of heat or mass transfer that can be obtained is higher with countercurrent than co-current (parallel) exchange because countercurrent maintains a slowly declining difference or
868:
up the tower as it is "stripped". The low boiling fraction is drawn off the top of the tower and the high boiling fraction drawn from the bottom. The process in the trays is a combination of
1328:(H) cations, while releasing water and the continued pumping out of calcium (Ca) and salt (Na and Cl ions). The repeated concentration by secretion of calcium and salt ions is inhibited by
478:
pumps each pumping only against a very small gradient, during the exit from the loop, returning the concentration inside the output pipe to its original concentration.
1117:
The specific heat capacity should be calculated on a mass basis, averaged over the temperature range involved. This is in keeping with the second law of thermodynamics
860:
particular when using hydrodynamic CCC instruments. The term partition chromatography is largely a synonymous and predominantly used for hydrostatic CCC instruments.
949:, producing nickel cobalt slurry. The nickel and cobalt in the slurry are removed from it almost completely using a CCD system exchanging the cobalt and nickel with
973:
allowing the heat to reach high temperatures using low cost, low temperature burning fuel. Historically this was developed by the
Japanese in certain types of the
817:. It has also been found in Namibian ostriches and other desert birds, where a buildup of salt concentration is due to dehydration and scarcity of drinking water.
1333:
840:
The glands remove the salt efficiently and thus allow the birds to drink the salty water from their environment while they are hundreds of miles away from land.
712:. The theory was acknowledged a year later after a meticulous study showed that there is almost no osmotic difference between liquids on both sides of nephrons.
639:
retained at 200 mOsm from the inside to the outside, while the concentration both inside and outside are gradually decreasing as the liquid flow advances.
561:
Various substances are passed from the liquid entering the nephrons until exiting the loop (See the nephron flow diagram). The sequence of flow is as follows:
255:
When heat is transferred, a thermally-conductive membrane is used between the two tubes, and when the concentration of a chemical substance is transferred a
1052:
Countercurrent processes have also been used to study the behavior of small animals and isolate individuals with altered behaviors due to genetic mutations.
322:. The system consists of two tubes, one with brine (concentrated saltwater), the other with freshwater (which has a low concentration of salt in it), and a
1105:
Both countercurrent exchange and countercurrent multiplication systems have been found in the kidneys. The latter in the loop of Henle, the first in the
508:
incoming fluid, in this example reaching 1200 mg/L. This is regulated by the pumping action on the returning tube as will be explained immediately.
2027:
1171:
240:
from one flowing current of fluid to another across a barrier allowing one way flow of the property between them. The property transferred could be
2011:
1154:
1473:, where Prof. Gottschalk points to the heated debate prior to the acceptance of the theory of the countercurrent multiplier action of the kidney
1203:, filtered blood is passed to the nephrons in the Bowman's capsule which surrounds the Glomerulus. (The blood leaves the Glomerulus in the
441:
between blood vessels in their legs to keep heat concentrated within their bodies. In vertebrates, this type of organ is referred to as a
390:
Nearly complete transfer in systems implementing countercurrent exchange, is only possible if the two flows are, in some sense, "equal".
1440:; Mylle, M. (1959), "Micropuncture study of the mammalian urinary concentrating mechanism: evidence for the countercurrent hypothesis",
1012:
which is built in a similar way to the
Anagama kiln, and must therefore withstand more harsh conditions, but reaches better efficiency.
89:
1009:
449:
use countercurrent exchange to remove water from urine so the body can retain water used to move the nitrogenous waste products (see
1031:
use countercurrent multiplication between rising and falling convection currents to reduce the number of stages needed in a cascade.
662:: Once leaving the loop of Henle the thick ascending limb can optionally reabsorb and re increase the concentration in the nephrons.
61:
42:
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at a small gradient. There is a gradual buildup of concentration inside the loop until the loop tip where it reaches its maximum.
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68:
2059:
1619:
618:
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inhibit water salt and calcium secretion from the collecting duct, while antidiuretic hormone and aldosterone catalyze it.
524:
75:
1482:
Smith, Homer W., The fate of sodium and water in the renal tubules, Bull. New York
Academy of Medicine 35:293–316, 1959.
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for absorbing oxygen from the water. It is mimicked in industrial systems. Countercurrent exchange is a key concept in
757:
are in colder water to which they are not acclimatized, they use this CCHE mechanism to prevent heat loss from their
166:, enabling a multiplied effect of many small pumps to gradually build up a large concentration in the buffer liquid.
108:
550:—an important part of the kidneys—allows for gradual buildup of the concentration of urine in the kidneys, by using
57:
1273:
The semipermeable membrane of the thin descending limb does not permit passage of ions or large dissolved molecules
583:
1554:
629:
Cl ions are pumped out of the liquid gradually lowering the concentration in the exiting liquid, but, using the
1224:) osmotic concentration in the limb nephrons. The urea absorption in the thick descending limb is inhibited by
425:
Countercurrent exchange is used extensively in biological systems for a wide variety of purposes. For example,
46:
1127:
Hsuan Jung Huang, Peixin He, Faulkner Larry R (1986). "Current multiplier for use with ultramicroelectrodes".
1046:
2064:
1106:
208:
163:
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very small single effect to significant separations. (Journal of the
American Society of Nephrology website)
1386:; Mylle, M. (1958), "Evidence that the mammalian nephron functions as a countercurrent multiplier system",
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892:
885:
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876:. Heat is supplied at the bottom, known as a "reboiler" and cooling is done with a condenser at the top.
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267:
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Initially the countercurrent exchange mechanism and its properties were proposed in 1951 by professor
2074:
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1077:
926:
82:
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using countercurrent heat exchange to keep heat from leaving their body while breathing out, during
1368:
Kuhn theorized and studied this mechanism already in the early 1940s. This was confirmed in 2001 in
658:
848:
2069:
1549:(Thirty-seventh ed.). Edinburgh: Churchill Livingstone. pp. 691–692, 791, 10011–10012.
1308:
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The thin ascending limb's membrane does not permit free passage of any substance including water.
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35:
150:
138:, the vapors bubble up through the downward flowing liquid while exchanging both heat and mass.
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Water or liquid with very low osmotic concentration leaving the nephrons is reabsorbed in the
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receives the concentrated substance. The incoming and outgoing tubes do not touch each other.
2005:
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1957:
1901:"Countercurrent separation: A new method for studying behavior of small aquatic organisms"
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and organic material leave the limb, gradually raising the concentration in the nephrons.
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use counter current exchange mechanisms for extracting high rates of the desired material.
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Hardendale Lime Works in the UK using countercurrent kilns to reach high temperatures
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In the cocurrent flow exchange mechanism, the two fluids flow in the same direction.
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Williams, Peter L.; Warwick, Roger; Dyson, Mary; Bannister, Lawrence H. (1989).
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Theoretically a similar system could exist or be constructed for heat exchange.
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Reabsorbing and increasing the concentration is done by optionally absorbing
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1045:(devices used to clean saltwater pools and fish ponds of organic matter) use
938:
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765:. Such CCHE systems are made up of a complex network of peri-arterial venous
739:
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Exchange current decantation depicted in centrifugal extractors as 1st stage
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food. The kidney cannot remove these quantities and concentrations of salt.
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The liquid finally reaches a low concentration of 100 mOsm when leaving the
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1925:
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are treated with CCD, after the original ore was treated with concentrated
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1997:
1944:
1839:"Behavioral Mutants Of Drosophila Isolated By Countercurrent Distribution"
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mechanism, always pumping against a constant and small osmotic difference.
495:
In the example shown in the image, water enters at 299 mg/L (NaCl / H
2037:
1337:
1295:
1229:
957:
950:
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Same principle is used in hemodialysis within artificial kidney machines.
1725:
1685:
1216:
The liquid from the Bowman's capsule reaches the thick descending limb.
1140:
903:
processing, the production of fine organic compounds, the processing of
393:
For a maximum transfer of substance concentration, an equal flowrate of
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Patent for a snow mask with a removable countercurrent exchange module
16:
Mechanism occurring in nature and mimicked in industry and engineering
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1321:
946:
912:
806:
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and two of his former students who called the mechanism found in the
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to transfer oxygen from the surrounding water into their blood, and
24:
1958:
Dusenbery David B., Sheridan Robert E., Russell
Richard L. (1975).
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Schmidt-Nielsen, Knut (1981). "Countercurrent systems in animals".
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904:
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358:
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The counter-current exchange system can maintain a nearly constant
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In countercurrent flow, the two flows move in opposite directions.
173:
Countercurrent exchange circuits or loops are found extensively in
142:
1793:
1610:
Gilroy, Anne M.; MacPherson, Brian R.; Ross, Lawrence M. (2008).
1257:
1245:
1001:
922:
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Countercurrent exchange in sea and desert birds to conserve water
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614:: after the tip (or 'bend') of the loop, the liquid flows in the
587:
555:
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which keeps the warmth from leaving the mask when breathing out.
445:(originally the name of the organ in the fish gills). Mammalian
409:
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to the buffer liquid in this example at 300 mg/L (NaCl / H
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374:, the hot fluid becomes cold, and the cold fluid becomes hot.
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inhibits salt secretion from the thin ascending limb, while
1019:
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is to occur (i.e. there can be no gap between the channels).
162:
pumps on the outgoing fluid's tubes, the system is called a
1614:. Stuttgart: Thieme Medical Publishers. pp. 318, 349.
1260:
inhibits the secretion from the thick descending limb, and
1253:
1221:
1217:
918:
844:
Countercurrent exchange in industry and scientific research
814:
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and confirmed by laboratory findings in 1958 by
Professor
900:
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The salt secreting gland has been found in seabirds like
385:
1366:
According to a book on Jewish scientists under the Reich
929:
using
Counter Current Decantation (CCD). In some mines,
481:
The incoming flow starting at a low concentration has a
594:), gradually raising the concentration in the nephrons.
326:
which allows only water to pass between the two, in an
236:
are two mechanisms used to transfer some property of a
196:
and manufacturing processes, for example in extracting
1364:
The original lecture was published in 1951 in German.
308:
is an example of a cocurrent flow exchange mechanism.
1637:"The Function of the Salt Gland in the Brown Pelican"
456:
271:
A comparison between the operations and effects of a
1634:
1609:
401:
is required. For maximum heat transfer, the average
1905:
Proceedings of the National Academy of Sciences USA
1846:
Proceedings of the National Academy of Sciences USA
1008:from organic or fossil matter, can be done using a
273:
cocurrent and a countercurrent flow exchange system
225:
Three topologies of countercurrent exchange systems
49:. Unsourced material may be challenged and removed.
1635:Schmidt-Nielsen, Knut; Fange, Ragnar (July 1958).
1898:
216:
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590:(and glucose and other ions are pumped out with
1683:
1575:Scholander, P. F. (1957). "The wonderful net".
1496:
1436:
1382:
1010:counter-current fixed bed ("up draft") gasifier
789:Sea and desert birds have been found to have a
365:
288:conditions of the stream with the higher flow.
262:
1960:"Chemotaxis-Defective Mutants of the Nematode
1836:
1471:Journal of International Society of Nephrology
1467:History of the urinary concentrating mechanism
630:
450:
346:Spiral counter-current heat exchange schematic
1747:Proctor, Noble S.; Lynch, Patrick J. (1993).
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410:Countercurrent exchange in biological systems
2010:: CS1 maint: multiple names: authors list (
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1153:: CS1 maint: multiple names: authors list (
724:Countercurrent exchange of heat in organisms
606:inside and outside are gradually increasing.
485:with water passing to the buffer liquid via
961:Countercurrent furnace (kiln) heat exchange
776:Another example is found in the legs of an
465:Counter current multiplication loop diagram
1574:
1563:
1476:
570:: Liquid enters the nephron system at the
300:Cocurrent and countercurrent heat exchange
291:
185:, originally the name of an organ in fish
1987:
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1924:
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1652:
582:: It then may reabsorb urea in the thick
109:Learn how and when to remove this message
1540:
1538:
1536:
1018:
980:
956:
879:
847:
727:
586:. Water is removed from the nephrons by
531:
460:
413:
341:
338:Countercurrent flow—almost full transfer
295:
266:
220:
134:combination of those. For example, in a
120:
1492:
1490:
1488:
1370:the translation to the original lecture
648:ascending limb and passing through the
2052:
969:can be manufactured in countercurrent
386:Conditions for higher transfer results
1761:
1533:
1485:
1220:may be reabsorbed into the low (300
499:O). Water passes because of a small
181:. In vertebrates, they are called a
47:adding citations to reliable sources
18:
2028:Countercurrent multiplier animation
1818:. University of Illinois at Chicago
1169:countercurrent multiplier animation
252:, or other properties of the flow.
13:
1710:10.1038/scientificamerican0159-109
1519:10.1038/scientificamerican0581-118
985:Cement counter-current rotary kiln
523:
457:Countercurrent multiplication loop
14:
2091:
2021:
1597:10.1038/scientificamerican0457-96
676:: The liquid urine leaves to the
1454:10.1152/ajplegacy.1959.196.4.927
519:
320:cocurrent concentration exchange
23:
1951:
1892:
1830:
1816:"Countercurrent Chromatography"
1808:
1782:
1755:
1740:
1677:
1628:
1603:
1430:
1376:
1358:
1342:
1314:
1301:
1285:
34:needs additional citations for
1684:Schmidt-Nielsen, Knut (1959).
1442:American Journal of Physiology
1276:
1267:
1239:
1210:
1185:
1161:
1120:
1111:
1099:
217:Three current exchange systems
1:
2034:Research about elephant seals
1093:
857:Countercurrent Chromatography
372:countercurrent heat exchanger
209:Countercurrent multiplication
2060:Chemical process engineering
1408:10.1126/science.128.3324.594
1047:counter current technologies
366:Countercurrent flow examples
263:Cocurrent flow—half transfer
7:
1469:an article in 'Kidney'—the
1083:Regenerative heat exchanger
1056:
746:, of a bird, for instance.
284:how long the exchanger is.
10:
2096:
1899:Dusenbery David B (1973).
1349:Atrial natriuretic peptide
1311:and returned to the blood.
1000:: the process of creating
773:at the periphery surface.
687:
579:Proximal convoluted tubule
546:A circuit of fluid in the
2030:from Colorado University.
1980:10.1093/genetics/80.2.297
1088:Countercurrent multiplier
1078:Heat recovery ventilation
733:the counter current flow.
706:Countercurrent multiplier
631:countercurrent multiplier
451:countercurrent multiplier
318:A similar example is the
164:countercurrent multiplier
58:"Countercurrent exchange"
1751:. Yale University Press.
1298:catalyzes the secretion.
921:can be separated from a
893:Liquid–liquid extraction
886:liquid–liquid extraction
659:Distal convoluted tubule
598:Loop of Henle Descending
528:Nephron Ion flow diagram
306:cocurrent heat exchanger
1837:Benzer Seymour (1967).
1309:Peritubular capillaries
915:, and other industries.
612:Loop of Henle Ascending
324:semi permeable membrane
292:Cocurrent flow examples
230:Countercurrent exchange
131:Countercurrent exchange
1962:Caenorhabditis elegans
1926:10.1073/pnas.70.5.1349
1867:10.1073/pnas.58.3.1112
1764:"Avian osmoregulation"
1180:University of Colorado
1036:Centrifugal extractors
1029:Zippe-type centrifuges
1024:
986:
962:
888:
853:
749:When animals like the
734:
543:
529:
483:semipermeable membrane
466:
422:
406:transferred properly.
403:specific heat capacity
347:
301:
277:
257:semipermeable membrane
226:
127:
1749:Manual of Ornithology
1334:Aantidiuretic hormone
1068:Bidirectional traffic
1022:
984:
960:
927:Merrill–Crowe process
883:
851:
731:
535:
527:
464:
437:use a countercurrent
417:
345:
299:
270:
224:
124:
2065:Industrial processes
1129:Analytical Chemistry
907:, the production of
897:nuclear reprocessing
744:lower legs, or tarsi
354:concentration flow.
191:chemical engineering
43:improve this article
1917:1973PNAS...70.1349D
1858:1967PNAS...58.1112B
1796:on 5 September 2008
1770:on 19 December 2019
1702:1959SciAm.200a.109S
1690:Scientific American
1589:1957SciAm.196d..96S
1577:Scientific American
1511:1981SciAm.244e.118S
1499:Scientific American
1400:1958Sci...128..594G
1191:Beginning with the
1141:10.1021/ac00126a070
761:, tail flukes, and
136:distillation column
1205:efferent arteriole
1193:afferent arteriole
1174:2011-06-06 at the
1025:
987:
963:
925:solution with the
889:
854:
751:leatherback turtle
735:
710:Carl W. Gottschalk
544:
530:
467:
423:
348:
302:
278:
250:chemical substance
234:cocurrent exchange
227:
177:, specifically in
128:
1762:Ritchison, Gary.
1621:978-1-60406-062-1
1583:(April): 96–110.
1438:Gottschalk, C. W.
1384:Gottschalk, C. W.
1332:and catalyzed by
1228:and catalyzed by
1135:(13): 2889–2891.
119:
118:
111:
93:
2087:
2075:Renal physiology
2016:
2015:
2009:
2001:
1991:
1955:
1949:
1948:
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1911:(5): 1349–1352.
1896:
1890:
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1852:(3): 1112–1119.
1843:
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1828:
1827:
1825:
1823:
1812:
1806:
1805:
1803:
1801:
1792:. Archived from
1790:"TheLiquidPhase"
1786:
1780:
1779:
1777:
1775:
1766:. Archived from
1759:
1753:
1752:
1744:
1738:
1737:
1681:
1675:
1674:
1656:
1632:
1626:
1625:
1612:Atlas of Anatomy
1607:
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1505:(May): 118–128.
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1109:
1103:
1043:protein skimmers
884:Counter flow in
827:active transport
740:venae comitantes
592:active transport
572:Bowman's capsule
552:active transport
501:osmotic pressure
476:active transport
429:use it in their
332:osmotic pressure
179:biologic systems
160:active transport
151:flow arrangement
114:
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1199:leading to the
1190:
1186:
1176:Wayback Machine
1166:
1162:
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1145:
1125:
1121:
1116:
1112:
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1006:carbon monoxide
846:
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667:Collecting duct
584:descending limb
567:Renal corpuscle
554:on the exiting
536:Loop of Henle (
522:
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362:liquid's heat.
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2070:Animal anatomy
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2023:
2022:External links
2020:
2018:
2017:
1974:(2): 297–309.
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1696:(1): 109–119.
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1627:
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1555:
1547:Gray's Anatomy
1532:
1484:
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1448:(4): 927–936,
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994:temperatures.
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953:heated water.
952:
948:
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941:and steam in
940:
939:sulfuric acid
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721:
719:
718:rete mirabile
715:
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700:in mammalian
699:
698:loop of Henle
695:
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520:In the kidney
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59:
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54:Find sources:
48:
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38:
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32:This article
30:
26:
21:
20:
2006:cite journal
1971:
1967:
1961:
1953:
1908:
1904:
1894:
1849:
1845:
1832:
1820:. Retrieved
1810:
1798:. Retrieved
1794:the original
1784:
1772:. Retrieved
1768:the original
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1303:
1287:
1278:
1269:
1264:catalyzes it
1241:
1212:
1197:blood vessel
1187:
1163:
1149:cite journal
1132:
1128:
1122:
1113:
1101:
1063:Anagama kiln
998:Gasification
975:Anagama kiln
865:Distillation
856:
855:
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41:Please help
36:verification
33:
2038:hibernation
1556:0443-041776
1465:. See also
1338:aldosterone
1296:aldosterone
1250:amino acids
951:flash steam
829:powered by
807:albatrosses
763:dorsal fins
714:Homer Smith
694:Werner Kuhn
2054:Categories
1353:urodilatin
1292:Furosemide
1252:, various
1201:Glomerulus
1107:vasa recta
1094:References
1073:Economizer
947:autoclaves
791:salt gland
778:Arctic fox
771:convection
202:sugar beet
69:newspapers
1718:0036-8733
1663:0004-8038
1330:thiazides
1322:potassium
913:biodiesel
720:in fish.
399:solutions
259:is used.
1968:Genetics
1886:16578662
1822:16 April
1800:16 April
1774:16 April
1734:13624738
1726:24944892
1462:13637248
1424:44770468
1416:13580223
1326:hydrogen
1324:(K) and
1230:lactates
1182:website.
1172:Archived
1167:See the
1057:See also
971:furnaces
945:covered
943:titanium
905:perfumes
799:pelicans
767:plexuses
759:flippers
755:dolphins
627:chloride
556:nephrons
395:solvents
359:gradient
143:gradient
99:May 2020
1998:1132687
1989:1213328
1945:4514305
1913:Bibcode
1854:Bibcode
1698:Bibcode
1671:4081974
1641:The Auk
1585:Bibcode
1527:7233149
1507:Bibcode
1396:Bibcode
1388:Science
1258:Dopamin
1246:Glucose
1234:ketones
1226:Sartans
1178:at the
1002:methane
923:cyanide
803:petrels
702:kidneys
688:History
625:Na and
621:. Salt–
588:osmosis
487:osmosis
447:kidneys
204:roots.
198:sucrose
83:scholar
1996:
1986:
1943:
1936:433494
1933:
1884:
1877:335755
1874:
1732:
1724:
1716:
1669:
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1618:
1553:
1525:
1460:
1422:
1414:
991:Cement
935:cobalt
931:nickel
813:, and
678:ureter
674:Ureter
623:sodium
175:nature
126:versa.
85:
78:
71:
64:
56:
1842:(PDF)
1722:JSTOR
1667:JSTOR
1420:S2CID
1041:Some
1034:Some
815:terns
811:gulls
650:thick
542:book)
435:birds
431:gills
370:In a
248:of a
238:fluid
200:from
187:gills
149:See:
90:JSTOR
76:books
2012:link
1994:PMID
1941:PMID
1882:PMID
1824:2011
1802:2011
1776:2011
1730:PMID
1714:ISSN
1659:ISSN
1616:ISBN
1551:ISBN
1523:PMID
1458:PMID
1412:PMID
1351:and
1336:and
1254:ions
1232:and
1222:mOsm
1218:Urea
1195:, a
1155:link
1004:and
967:Lime
933:and
919:Gold
911:and
872:and
753:and
646:thin
616:thin
427:fish
421:= RM
397:and
242:heat
232:and
62:news
1984:PMC
1976:doi
1931:PMC
1921:doi
1872:PMC
1862:doi
1706:doi
1694:200
1649:doi
1593:doi
1581:196
1515:doi
1503:244
1450:doi
1446:196
1404:doi
1392:128
1137:doi
901:ore
831:ATP
652:one
453:).
45:by
2056::
2008:}}
2004:{{
1992:.
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