✪✪✪ Potassium Chloride Lab Report
Table presents a summary of investigations examining the Potassium Chloride Lab Report of dehydration on muscular strength. Killed in a lab accident at DuPont Moral Ambiguity In Mary Shelleys Frankenstein. Potassium Chloride Lab Report healthy Potassium Chloride Lab Report, whose body fluid osmolality rises as a Potassium Chloride Lab Report of sweating, the osmolality of CF patients does not increase due to high Potassium Chloride Lab Report of sodium and chloride in Potassium Chloride Lab Report sweat. Potassium Chloride Lab Report another Potassium Chloride Lab Report, three collegiate wrestlers died of cardiorespiratory arrest while undergoing severe and rapid weight loss combined with stressful exercise Potassium Chloride Lab Report the heat Remick A Critique Of Descartes Argument al. If persons perform physical activity in hot weather, then daily Potassium Chloride Lab Report requirements will be markedly increased. Daily water turnover rates were approximately 3.
Preparing Potassium Chloride Solution using steering system
A typical tablet weighs mg, with mg of potassium iodide and 30 mg of excipients , such as binding agents. Potassium iodide cannot protect against any other mechanisms of radiation poisoning , nor can it provide any degree of protection against dirty bombs that produce radionuclides other than those of iodine. The potassium iodide in iodized salt is insufficient for this use. The World Health Organization does not recommend KI prophylaxis for adults over 40 years, unless the radiation dose from inhaled radioiodine is expected to threaten thyroid function, because the KI side effects increase with age and may exceed the KI protective effects; " Such radiation doses will not occur far away from an accident site. The U. Department of Health and Human Services restated these two years later as "The downward KI potassium iodide dose adjustment by age group, based on body size considerations, adheres to the principle of minimum effective dose.
The recommended standard daily dose of KI for all school-age children is the same 65 mg. However, adolescents approaching adult size i. Neonates ideally should receive the lowest dose 16 mg of KI. SSKI i. This is not the same as blocking the thyroid's release of thyroid hormone, for which the adult dose is different and is actually higher by a factor of 7 or 8 [ citation needed ] , and for which KI anti-radiation pills not a common medical treatment form of KI are not usually available in pharmacies, or normally used in hospitals, or by physicians.
For protection of the thyroid against radioiodine iodine contamination, the convenient standard mg KI pill is used, if available. It can also cause sialadenitis an inflammation of the salivary gland , gastrointestinal disturbances, and rashes. Potassium iodide is also not recommended for people with dermatitis herpetiformis and hypocomplementemic vasculitis — conditions that are linked to a risk of iodine sensitivity. There have been some reports of potassium iodide treatment causing swelling of the parotid gland one of the three glands that secrete saliva , due to its stimulatory effects on saliva production. The anti-radioiodine doses used for I uptake blockade are lower, and range downward from mg a day for an adult, to less than this for children see table.
At maximal doses, and sometimes at much lower doses, side effects of iodide used for medical reasons, in doses of times the normal nutritional need, may include: acne, loss of appetite, or upset stomach especially during the first several days, as the body adjusts to the medication. More severe side effects that require notification of a physician are: fever, weakness, unusual tiredness, swelling in the neck or throat, mouth sores, skin rash, nausea, vomiting, stomach pains, irregular heartbeat, numbness or tingling of the hands or feet, or a metallic taste in the mouth. In the event of a radioiodine release the ingestion of prophylaxis potassium iodide, if available, or even iodate, would rightly take precedence over perchlorate administration, and would be the first line of defence in protecting the population from a radioiodine release.
However, in the event of a radioiodine release too massive and widespread to be controlled by the limited stock of iodide and iodate prophylaxis drugs, then the addition of perchlorate ions to the water supply, or distribution of perchlorate tablets would serve as a cheap, efficacious, second line of defense against carcinogenic radioiodine bioaccumulation. The ingestion of goitrogen drugs is, much like potassium iodide also not without its dangers, such as hypothyroidism.
In all these cases however, despite the risks, the prophylaxis benefits of intervention with iodide, iodate or perchlorate outweigh the serious cancer risk from radioiodine bioaccumulation in regions where radioiodine has sufficiently contaminated the environment. Potassium iodide in its raw form is a mild irritant and should be handled with gloves. Chronic overexposure can have adverse effects on the thyroid. Potassium iodide is a possible teratogen. KI is used with silver nitrate to make silver iodide AgI , an important chemical in film photography.
KI is a component in some disinfectants and hair treatment chemicals. KI is also used as a fluorescence quenching agent in biomedical research, an application that takes advantage of collisional quenching of fluorescent substances by the iodide ion. Potassium iodide is a component in the electrolyte of dye sensitised solar cells DSSC along with iodine. Potassium iodide finds its most important applications in organic synthesis mainly in the preparation of aryl iodides in the Sandmeyer reaction , starting from aryl amines. Aryl iodides are in turn used to attach aryl groups to other organics by nucleophilic substitution, with iodide ion as the leaving group.
It crystallises in the sodium chloride structure. It is produced industrially by treating KOH with iodine. It is a white salt , which is the most commercially significant iodide compound, with approximately 37, tons produced in It absorbs water less readily than sodium iodide , making it easier to work with. Aged and impure samples are yellow because of the slow oxidation of the salt to potassium carbonate and elemental iodine. This reaction is employed in the isolation of iodine from natural sources.
Air will oxidize iodide, as evidenced by the observation of a purple extract when aged samples of KI are rinsed with dichloromethane. As formed under acidic conditions, hydriodic acid HI is a stronger reducing agent. Through this reaction, iodine is used in redox titrations. Aqueous KI 3 , " Lugol's solution ", is used as a disinfectant and as an etchant for gold surfaces. Potassium iodide and silver nitrate are used to make silver I iodide , which is used for high speed photographic film and for cloud seeding :. KI serves as a source of iodide in organic synthesis. A useful application is in the preparation of aryl iodides from arenediazonium salts. KI, acting as a source of iodide, may also act as a nucleophilic catalyst for the alkylation of alkyl chlorides , bromides , or mesylates.
Potassium iodide's KI value as a radiation protective thyroid blocking agent was demonstrated following the Chernobyl nuclear reactor disaster in April, , a saturated solution of potassium iodide SSKI was administered to Reports differ concerning whether people in the areas immediately surrounding Chernobyl itself were given the supplement. The use of KI With the passage of time, people living in irradiated areas where KI was not available have developed thyroid cancer at epidemic levels, which is why the US Food and Drug Administration FDA reported "The data clearly demonstrate the risks of thyroid radiation KI can be used [to] provide safe and effective protection against thyroid cancer caused by irradiation.
Chernobyl also demonstrated that the need to protect the thyroid from radiation was greater than expected. Within ten years of the accident, it became clear that thyroid damage caused by released radioactive iodine was virtually the only adverse health effect that could be measured. As reported by the NRC, studies after the accident showed that "As of , except for thyroid cancer, there has been no confirmed increase in the rates of other cancers, including leukemia, among the But equally important to the question of KI is the fact that radioactivity releases are not "local" events. Researchers at the World Health Organization accurately located and counted the cancer victims from Chernobyl and were startled to find that "the increase in incidence [of thyroid cancer] has been documented up to km from the accident site Over 11, cases have already been reported.
These findings were consistent with studies of the effects of previous radioactivity releases. In , millions of Japanese were exposed to radiation from nuclear weapons, and the effects can still be measured. Today, nearly half The development of thyroid cancer among residents in the North Pacific from radioactive fallout following the United States' nuclear weapons testing in the s on islands nearly miles downwind of the tests were instrumental in the decision by the FDA to issue a request for the availability of KI for thyroid protection in the event of a release from a commercial nuclear power plant or weapons-related nuclear incident.
Noting that KI's effectiveness was "virtually complete" and finding that iodine in the form of KI was substantially superior to other forms including iodate KIO 3 in terms of safety, effectiveness, lack of side effects, and speed of onset, the FDA invited manufacturers to submit applications to produce and market KI. It was reported on March 16, , that potassium iodide tablets were given preventively to U. Naval air crew members flying within 70 nautical miles of the Fukushima Daiichi Nuclear Power Plant damaged in the earthquake 8.
The measures were seen as precautions, and the Pentagon said no U. By March 20, the US Navy instructed personnel coming within miles of the reactor to take the pills. In the Netherlands, the central storage of iodine-pills is located in Zoetermeer , near The Hague. In , the Dutch government distributed pills to hundreds of thousands of residents who lived within a certain distance of nuclear power plants and met some other criteria.
As of , potassium iodide tablets are made available free of charge for all residents in all pharmacies throughout the country. Three companies Anbex, Inc. In , Fleming Co. ThyroShield is currently not in production. The Swedish manufacturing facility for Thyrosafe, a half-strength potassium iodide tablet for thyroid protection from radiation, was mentioned on the secret US Critical Foreign Dependencies Initiative leaked by Wikileaks in Tablets of potassium iodide are supplied for emergency purposes related to blockade of radioiodine uptake, a common form of radiation poisoning due to environmental contamination by the short-lived fission product I.
For reasons noted above, therapeutic drops of SSKI, or mg tablets of KI as used for nuclear fission accidents, are not used as nutritional supplements, since an SSKI drop or nuclear-emergency tablet provides to times more iodine than the daily adult nutritional requirement. Dedicated nutritional iodide tablets containing 0. Potassium iodide can be conveniently prepared as a saturated solution, abbreviated SSKI. This method of delivering potassium iodide does not require a method to weigh out the potassium iodide so it can be used in an emergency situation.
Faculty member killed when someone lit the lighter of an autoclave near a hexane spill, producing a huge explosion. Student killed when someone lit the lighter of an autoclave near a hexane spill, producing a huge explosion. Tarun K. Mal , Cleveland State University. Unknown , Moltech Power Systems, Taiwan. A fatal silane explosion occurred during a SiN 3 -deposition process. Kenton Joel Carnegie , University of Waterloo, geological engineering student, wolf attack during field work in Athabasca basin northern Saskatchewan Antonina Presnyakova , Russia. A researcher at Russian biological weapons research facility VECTOR died after accidentally pricking herself with a needle contaminated with Ebola virus.
Unknown , St. Paul, Minnesota, Vet Tech Hospital, an employee was trapped inside steam washer used to clean animal cages while the washer was in the final rinse cycle. The employee could not open the door from the inside, could not stop the washer, and was fatally burned. Unknown , Rochester, NY, Industrial lab explosion. Robert Goldhammer , University of Texas, Geology Department, Assistant Professor was killed when his vehicle rolled over on the way to the field camp.
Visiting scholar was killed when his vehicle rolled over on the way to the field camp. Unknown 8 , Journal of Clinical Microbiology report eight fatal lab infections from meningitis bacteria. Six were in USA. Nitrogen suffocation. Unknown , Scotland, Nitrogen suffocation. Unknown , Edmonton, Canada, Agat Laboratories, toluene inhalation death. High school senior electrocuted in science class while learning to use a volt meter. Elizabeth Griffin , Atlanta, GA. Yerkes Primate Center. Griffin was working with Rhesus monkeys infected with Herpes B virus. One monkey flung some debris from its cage that hit Griffin in the eye. Griffin contracted the disease and died six weeks later.
Karen Wetterhahn , Dartmouth College. Wetterhahn was working with a dimethylmercury compound using latex gloves. Latex does not provide sufficient protection from the chemical and she died of mercury poisoning. Visiting Scholar Xia Hai-ping hit a cabinet, causing bottles of chemicals to shatter on the ground. Coughing and overcome with fumes, he went for help.
Meanwhile Leung, a year-old grad student, unwittingly walked into the lab to wash his eyes and succumbed to the fumes. The chemicals were later determined to be acryloyl chloride and methacrylic anhydride. Michael Hanly , New York City. Discarded hydrofluoric acid killed sanitation worker Unknown , Collegeville, PA. Sterling Winthrop Pharmaceutical. Unknown , Western Australia. Unknown , Pasadena, TX, High school student drowned on biology field trip. Jeanne Messier , Reno, NV. UCSD biology grad student contracted hantavirus in field work. A cold fusion cell at Stanford Research Institute blew up while the British electrochemist was bending over it, killing him instantly. Unknown 2 , Hong Kong. University instructor and grad student suffocated in cold room when liquid nitrogen spilled.
GE Plastics Research Center. Centrifuge explosion. Unknown , Pennsylvania. Pressure vessel explosion at Merck lab. Unknown , Edwardsville, IL. Hydrogen explosion while drying solvent at Southern Illinois University. Theo Annin , Western Ontario University. Ether fire in fume hood. Unknown , Checotah, OK. Cyanide poisoning. Unknown 2 , Osaka University. Silane cylinder contaminated with nitrous oxide exploded, killing two graduate students.
Unknown , New Jersey physics student electrocuted. Unknown , Okinawa, Japan, High school student drowns during oceanography class. Unknown , Japan. A silane explosion in a gas cabinet killed one worker. Unknown , New Jersey. High school student electrocuted working on TV set in physics class. Unknown 2 , Michigan. Two analysts die from exposure to Herpes B virus in lab. Nikolai Ustinov , Koltsovo, Russia. A researcher studying Marburg virus accidentally pricked himself with a syringe containing the virus. Unknown 4 , McMasterville, Quebec. Unknown , California high school custodian went into coma and died following inhalation of old chemicals discarded in dumpster by new high school teacher.
Silane explosion at Gollob Analytical Services chemical testing plant. Unknown , Moscow. Unknown , Bedford, MA. Lincoln Lab worker dies from exposure to undetected arsine leak. Robert J. Long , Tamaqua, PA. Research and development laboratory employee killed in explosion at Atlas Powder Company. Unknown , Minneapolis. Autoclave exploded when year-old opened it. Helena Zinger , Antwerp, Belgium. Died in unidentified lab accident. Unknown , San Antonio, TX. Lee High School student electrocuted in science lab.
Unknown , San Francisco, CA. Unknown , Golden, CO. Engineering graduate student died from exposure to hydrogen sulfide at Colorado School of Mines. Unknown , Michigan. Lab technician died from burns sustained from being trapped in cage cleaning autoclave. Unknown 2 , Corning, NY. Sullivan Research Facility hydrofluoric acid tank leaked. Two killed in clean-up.
High School Student electrocuted in science lab. Unknown , Kazakstan, Russia. Ether explosion in refrigerator at the National Academy of Science. Unknown , Boston, MA. Sunny Su , Dartmouth, MA. Graduate student died in solvent explosion and fire at the University of Massachusetts. Unknown 64 , Sverdlovsk, Russia. The exact number of victims remains unknown due to government coverup, but it could be as many as who died from exposure to anthrax at a biological weapons lab when someone forgot to install a filter on an exhaust. Unknown , Arizona State University. Unknown , Washington State University. High school student died when the nitroglycerine he had synthesized blew up in his pocket on the way to the football field.
Unknown , College Park, MD. Janet Parker , Medical School at Birmingham University UK , year-old medical photographer died from laboratory exposure to smallpox. Unknown 54 , Nigeria. A report compiling a number of laboratory-acquired viral infections at the Virus Research Laboratory in Ibadan, Nigeria, details 54 deaths. Unknown , UK. A lab worker died of Ebola after being accidently stuck by a contaminated needle. Unknown , Texas high school student died of injuries sustained in alcohol fire.
He was trying to refill the lamp while it was still lit. Unknown , Arizona State University graduate student was trapped in lab fire. Unknown , Enschede, Netherlands. Organic chemist died of edema from methylfluorosulfate exposure at Technische Hogeschool Twente. Adrian Droog, a 9th-grade teacher at Inala State High School, was demonstrating how to make a rocket using potassium chlorate and sulphur when the mixture exploded.
The teacher and a student were killed, and several other students were injured. Unknown , Stanford University. Graduate student killed when broken lid flew off vacuum desiccator. Unknown 2 , London. A year-old laboratory assistant at the London School of Hygiene and Tropical Medicine was infected with smallpox virus after harvesting live virus from eggs. She survived, but infected two visitors of a patient in an adjacent bed, both of whom died. MIT grad student electrocuted while working on live circuits. Unknown 2 , New Haven, CT. Solid propellant explosion kills two lab workers at Olin-Matheson. Unknown 3 , Russia. Three lab technicians died from smallpox as a result of a field test at a Soviet biological weapons facility on an island in the Aral Sea. Unknown , Seattle, WA.
P-Chem undergraduate killed in explosion from while pouring waste solvent at the University of Washington. Unknown , Seattle. Sodium explosion in physical chemistry lab kills student at University of Washington. Ray Kemp , Columbus, OH. Potassium cyanide poisoning at Ohio State University. Unknown 7 , Marburg, Germany. Seven patients died from lab worker exposure to virus from infected Grivet monkeys from Uganda.
John Gallant , Westbrook, ME. High school student electrocuted while learning to use oscilloscope in physics class. Unknown , Port Evan, NY. Chemist killed in explosion at Hercules Powder Company. TBW is usually measured by volume distribution of an appropriate indicator e. Table provides TBW values for different age and gender groups based upon indicator dilution methods Altman, Women and older persons have reduced TBW primarily because of having lower fat-free mass and increased body fat.
Athletes have relatively high TBW values by virtue of having a high fat-free mass, low body fat, and high skeletal muscle glycogen levels. High skeletal muscle glycogen levels increase the water content of fat-free tissue due to osmotic pressure exerted by glycogen granules within the muscle sarcoplasm Neufer et al. The ECF is further divided into the interstitial and plasma spaces. These are not static volumes, but represent the net effects of dynamic fluid exchange with varying turnover rates between compartments Guyton and Hall, Perturbations such as exercise, heat exposure, fever, diarrhea, trauma, and skin burns will greatly modify the net volumes and water turnover rates between these fluid compartments. Water passes through membranes from regions of lower to higher solute concentration by osmosis, which attempts to equalize the concentration differences across the membrane.
Cell membranes are freely permeable to water, but they are only selectively permeable to solutes. Water thus distributes across cell membranes to equalize the osmotic concentrations of extracellular and intracellular fluids. Although the two compartments contain different individual solute concentrations, the total equilibrium concentration of cations and anions is the same in each compartment as described by the Gibbs-Donnan equilibrium.
In the ECF, the most abundant cation is sodium, while chloride and bicarbonate are the primary anions. These ions represent 90 to 95 percent of the osmotically active components of the ECF, and changes in their content alter the ECF volume. In the ICF, the most abundant cations are potassium and magnesium, while proteins are the primary anions. The marked differences in sodium and potassium concentrations be-. Water exchange between the intravascular and interstitial spaces occurs in the capillaries. Capillaries of different tissues have varied anatomic structures and therefore different permeability to water and solutes. The transcapillary forces that determine if net filtration i.
Oncotic pressure is the osmotic pressure attributed to serum protein concentration e. Generally, filtration occurs at the arterial end of the capillary, while absorption occurs at the venous end. Incomplete fluid replacement resulting in decreased total body water affects each fluid space as a consequence of free fluid exchange Costill and Fink, ; Durkot et al. The distribution of body water loss among the fluid spaces, as well as among different body organs during water deficit dehydration or hypohydration , was determined in an animal model Nose et al. The fluid deficit in rats thermally dehydrated by 10 percent of body weight was apportioned between the intracellular 41 percent and extracellular 59 percent spaces.
Organ fluid loss was 40 percent coming from muscle, 30 percent from skin, 14 percent from viscera, and 14 percent from bone. Neither the brain nor liver lost significant water content. Various dehydration methods influence the partitioning of water loss from the fluid spaces Mack and Nadel, Body water balance depends on the net difference between water gain and water loss. Water gain occurs from consumption liquids and food and production metabolic water , while water losses occur from respiratory, skin, renal, and gastrointestinal tract losses.
Water is normally consumed by mouth via liquid and food, and this mixture is digested and absorbed within the gastrointestinal tract. Therefore, water intake can be estimated from measured liquid volumes and tables of food composition. Water losses can be estimated from a variety of physiological and biophysical measurements and calculations Adolph, ; Consolazio et al. The following sections describe each source of water loss or production listed in this table. The amount of respiratory water loss, via evaporation within the lungs, is dependent on both the ventilatory volume and water vapor pressure gradient Mitchell et al. Ventilatory volume is increased by physical activity, hypoxia, and hypercapnia, whereas the water vapor pressure is modified by the ambient temperature, humidity, and barometric pressure.
Physical activity generally has a greater effect on respiratory water loss than do environmental factors. Ambient air temperature and humidity modify respiratory water losses. The kidneys are responsible for regulating the volume and composition of the ECF via a series of intricate neuroendocrine pathways Andreoli et al. Renal fluid output can vary depending upon the specific macronutrient, salt, and water load. However, for persons consuming an average North American diet, some of these effects may not be discernable Luft et al.
Since there is a limit to how much the kidneys can concentrate urine, the minimal amount of water needed is determined by the quantity of end products that need to be excreted e. On typical Western diets, an average of mOsmol of electrolytes and other. Healthy older individuals, however, cannot concentrate urine as well as young individuals and thus have a higher minimum urine output. Urine output varies inversely with body hydration status. Figure depicts the hyperbolic relationship between urine output and. Reprinted with permission, from Lee The extremes depicted in Figure can be exceeded. Urine output can vary widely to maintain total body water; however, there are clearly limits to the amount of conservation and excretion. Physical activity and climate also affect urine output.
Exercise and heat strain will reduce urine output by 20 to 60 percent Convertino, ; Mittleman, ; Zambraski, , while cold and hypoxia will increase urine output Freund and Young, ; Hoyt and Honig, Water loss through the skin occurs via insensible diffusion and secreted sweat. During heat stress, eccrine sweat glands secrete sweat onto the skin surface, which cools the body when water evaporates from the sweat. For a given hot weather condition, the required sweating rate for evaporative cooling is dependent upon the physical activity level metabolic rate.
If the activity is 20 percent efficient, the remaining 80 percent of metabolic energy produced is converted to heat in the body so that W 0. If these persons performed exercise in a hot environment that enabled only evaporative heat loss and they did not sweat, their body temperatures would increase by approximately 1. Since the latent heat of evaporation is 2. Because secreted sweat drips from the body and is not evaporated, higher sweat secretions are often needed to achieve these cooling demands.
If a person is physically active and exposed to environmental heat stress, sweat losses to avoid heat storage can be substantial over a hour period. For persons living in hot climates, daily sweat losses often exceed several liters. As described above, daily sweat losses are determined by the evaporative heat loss requirements, which are influenced by the metabolic rate above example and environment. The environmental factors that modify sweat losses include clothing worn, ambient temperature, humidity, air motion, and solar load. Therefore, considerable variability will exist for daily sweat losses among different people. Figure provides the distribution of daily sweat-. Percent incidence refers to the percentage of the subject population achieving the given daily sweat loss.
The average daily sweat loss for 97 men in the desert was 4. The lower daily sweat losses in the tropics were probably due to lower ambient temperatures and lower solar load both acting to lower the required evaporative cooling , as the precise activity levels of both groups were unknown. Metabolic water is formed by oxidation of hydrogen-containing substrates during metabolism or energy-yielding nutrients. Oxidation of carbohydrate, protein, and fat produces metabolic water of approximately 15, Therefore, metabolic water production is proportional to the energy expenditure with a small adjustment for the substrate oxidized. Figure shows the metabolic water production relative to daily energy expenditure for persons eating a mixed diet Hoyt and Honig, Therefore, a reasonable estimate of daily metabolic.
Reprinted with permission, from Hoyt and Honig Hence, respiratory water losses are roughly equivalent to, or offset by, metabolic water production Table ; Hoyt and Honig, Metabolic water, a by-product of metabolizing energy-yielding nutrients from foods into carbon dioxide and energy, does not include the water present in a foodstuff itself. This is considered compositional water, or moisture. It is often determined analytically as the difference in weight of a food item before and after drying to a constant weight. Fluid is consumed in the form of food and beverages, and, regardless of form, is absorbed by the gastrointestinal tract and acts the same physiologically. In one survey of the adult U. National survey data for adults Appendix Tables D-1 , D-3 , and D-4 likewise suggest that approximately 20 percent of water comes from food, and the remaining 80 percent comes from fluids.
Drinking induced by water deprivation is homeostatic Greenleaf and Morimoto, Other factors e. Over an extended period, fluid consumption will match body water needs if adequate amounts are available. However, mismatches can occur over short periods Johnson, The fluid intake for healthy adults can vary markedly depending on activity level, environmental exposure, diet, and social activities; nonetheless, for a given set of conditions, intake is reproducible within persons Johnson, Therefore, it is reasonable to assume that for large population studies of apparently healthy individuals, the fluid volume consumed is equal to or greater than body water needs.
Adolph described the rates of water gain and water loss relative to different levels of water deficit and excess. Induced water deficits or water excesses resulted in compensatory changes in water gains and water losses until water balance was reestablished. Likewise, Newburgh and colleagues demonstrated the accuracy of water balance studies to be within 0. Therefore, ad libitum water balance studies can be used to estimate daily water requirements, provided the subjects have adequate time for rehydration and physiologic compensation Adolph, ; Newburgh et al. In both these studies, total water intake was measured. Table presents water balance studies that have estimated daily total water requirements for infants and children.
Note that daily total water requirements increase with age from early infancy approximately 0. Since infants have rapid growth, some investigators express the daily water needs relative to body mass. After reviewing early water balance studies, Adolph concluded that for most adult men,. Thus total water intake was calculated as 85 percent of total volume intake. Subsequent studies by Johnson recommended minimum daily water requirements of no less then 0.
Table presents water balance studies that have estimated daily total water requirements for adults. These requirements are above minimal levels because some physical activity although usually nominal was allowed and because individuals self-selected the volume of consumed fluids i. For the prolonged bed-rest studies, greater emphasis was placed on data obtained during the initial week, if available. Water balance studies suggest that the required water intake to maintain water balance for resting adult men is approximately 2.
If modest physical activity is performed, the. Cold exposure did not alter intake, but heat stress increased total daily water intake Welch et al. Limited data were available for women. Women are physically smaller, thus they probably have lower water requirements due to lower metabolic expenditures. A study of three Japanese women likely smaller than average U. Water turnover studies have been conducted to evaluate water needs and assume a balance between influx and efflux Nagy and Costa, Rates of body water turnover can be determined by administering a drink with deuterium D 2 O or tritium 3 H 2 O labeled water and then following the decline or disappearance in hydrogen isotope activity over time. The isotope activity declines because of loss of the labeled water via excretion, evaporation, and dilution from intake of unlabeled water.
If proper procedures are employed, these measurements will yield values within 10 percent or less of actual water flux Nagy and Costa, Figure provides data on the daily water turnover for infants and children Fusch et al. Water turnover when expressed. Reprinted with permission, from Fusch et al. Copyright by Springer-Verlag. It declines further, but at a slower pace during childhood and adolescence. Daily fluid intake in bottle-fed infants was compared over a day study period using two methods to determine intake Vio et al. Water turnover as measured by deuterium tracer was compared with directly measured fluid intake. Daily fluid intakes of 0. Other studies have found close agreement Butte et al.
Table provides studies examining daily water turnover for adults in a variety of conditions. These values are generally higher than in water balance studies because subjects are often more active and exposed to outside environments. Daily water turnover rates were approximately 3. Several studies found daily water turnover rates greater than 5 L; presumably these were more active persons who may have encountered heat stress. Women generally had approximately 0. Water turnover was measured in noninstitutionalized adults ranging from 40 to 79 years of age who lived in temperate climates Raman et al.
Daily turnover averaged 3. The water turnover values were corrected for metabolic water and water absorption from humidity to provide preformed water values. The preformed water values averaged 3. The lower values in women were not accounted for by differences in body size. Total body water TBW is accurately determined by dilution of a variety of indicators. Repeated measurements are required to assess total body water changes.
The technical requirements and cost for. Bioelectric impedance analysis BIA has recently gained attention because it is simple to use and allows rapid, inexpensive, and noninvasive estimates of TBW. Absolute values derived from this technique correlate well with TBW values obtained by isotope dilution Kushner and Schoeller, ; Kushner et al. These valida-. Because fluid, electrolyte, and plasma protein concentrations can have independent effects, BIA can provide misleading values regarding dehydration or hyperhydration status Gudivaka et al. However, recently a multifrequency BIA with Cole-Cole analysis was reported not to be sensitive to hypertonic dehydration Bartok et al.
Plasma osmolality provides a marker of dehydration levels. Osmolality is closely controlled by homeostatic systems and is the primary physiological signal used to regulate water balance by hypothalamic and posterior pituitary arginine vasopressin secretion , resulting in changes in urine output and fluid consumption Andreoli et al. Water deprivation if it exceeds solute losses increases the osmolality of plasma and of the ECF and thus fluids bathing the hypothalamus. This causes loss of ICF from osmoreceptor neurons, which then signals the release of arginine vasopressin from the hypothalamus and the posterior pituitary. Arginine vasopressin acts on the renal tubules to increase water reabsorption.
Arginine vasopressin release is proportional to increased plasma osmolality and decreased plasma volume. While body water loss will induce plasma volume reduction and increased plasma osmolality, the influence of body water loss on each depends upon the method of dehydration, physical fitness level, and heat acclimatization status Sawka, ; Sawka and Coyle, Table provides results from some of these studies. Figure provides a compilation of 19 studies subjects where plasma osmolality was measured at several hydration levels.
TBW was either directly measured or calculated based upon body composition information. Similar relationships have been reported based on smaller sample sizes of individual data Sawka et al. FIGURE Relationship of change in plasma osmolality to change in total body water from 19 studies representing subjects Armstrong et al. The data points represent mean data reported in these studies. Clearly, plasma osmolality provides a good marker for dehydration status if water loss is greater than solute loss. When solute and water are lost proportionately, such as with diarrhea or vomiting, osmolality remains constant and vasopressin release is blunted. However, the resulting ECF loss will stimulate the renin-angiotensin-aldosterone system as a means to increase sodium and hence water retention Share et al.
This mechanism appears to be less robust in elderly individuals Dontas et al. These data indicate that persons in the lowest and highest deciles of total water intake were not systematically dehydrated or hyperhydrated. In agreement. In general, serum and plasma osmolality values are usually nearly identical; however, several handling and analytical factors can cause small differences between them Tietz, Sodium is the primary cation of the ECF. Any loss of water in greater proportion than electrolyte losses will increase sodium concentrations in ECF compartments. Figure provides a compilation of four studies 32 subjects where plasma sodium concentration was measured at several hydration levels.
If data are analyzed for only the studies that. FIGURE Relationship of change in plasma sodium to change in total body water from 4 studies representing 32 subjects Fallowfield et al. Based on this data, plasma sodium changes are not as strongly related to changes in body hydration status as plasma osmolality changes. Figure depicts these data; note that the magnitude of increased plasma sodium concentration is markedly less than the increase in plasma osmolality. Therefore, the smaller increase in sodium concentration for a given water deficit may result in a smaller range for interstudy analyses and lead to.
FIGURE Relationship of change in plasma osmolality and plasma sodium concentration changes from thermal dehydration. Data from Montain et al. Hyperhydration induces a modest increase in plasma volume Freund et al. Dehydration will decrease plasma volume, but the magnitude of reduction is variable. For example, heat acclimatized persons have a smaller plasma volume reduction for a given body water deficit than do unacclimatized persons Sawka et al. By virtue of having a more dilute sweat, heat acclimatized persons have additional solutes remaining within the extracellular space to exert an osmotic pressure and redistribute fluid from the intracellular space. Figure provides a compilation of 16 studies subjects where plasma volume was measured at several hydration levels.
FIGURE Relationship of change in plasma volume to change in total body water from 16 studies representing subjects Armstrong et al. However, since subject status e. Although blood urea nitrogen BUN is primarily considered an indicator of kidney function, it is also used as an indicator of dehydration in clinical settings. However, BUN is also directly related to protein intake. Therefore, while BUN. An elevated BUN:creatinine ratio greater than 25 was seen in 2 of 37 elderly, long-term care patients who experienced no febrile episodes and no documentation of impaired oral intake Weinberg et al.
The BUN:creatinine ratio remained relatively constant over a 6-month period in stable male residents Weinberg et al. Still, although the BUN:creatinine ratio, like BUN itself, has been used to assess hydration status, lack of specificity hinders its use as a measure of hydration status. Urine volume is often used as an indicator of hydration status.
The color of urine darkens or lightens with low or high output levels because the solute load is either concentrated or diluted, respectively. Thus urine color has been used as an indicator of hydration status Wakefield et al. However, no precise relationship between urine color and hydration level exists. Furthermore, diet, medications, and vitamin use can affect urine color. Nonetheless, urine color can provide a good educational tool for dehydration or overhydration Casa et al.
A urine color chart for athletes to teach them about proper hydration is available Casa et al. Although not nearly as precise as biochemical measures, urine color can give a crude indication of hydration status. Because urine becomes more concentrated with dehydration, both urine specific gravity and urine osmolality have been used as indicators of hydration status. It should be noted that the validity of the urine specific gravity and. Many studies have used these urine indices to access fluid balance and found poor Armstrong et al.
It has generally been accepted that a urine specific gravity of less than or equal to 1. Adolph b published individual data regarding urine specific gravity at different levels of water deficit Figure Urine specific gravity increases with water deficit; however, considerable individual variability exists. Although a urine specific gravity greater than 1. Therefore, in the setting of such variability, there may be no single threshold for urine osmolality and hydration status. In addition, urine osmolality is increased when osmotically active solutes are excreted, such as glucose in patients with uncontrolled diabetes mellitus Tilkian et al. For these reasons i. Saliva specific gravity is slightly higher than water Shannon and Segreto, Several studies have examined dehydration and sali-.
Salivary flow was shown to decrease after a water deficit exceeding 2 percent of body weight, but there was considerable variability in response Adolph and Wills, Significant decreases in saliva flow rate were found during dehydration of 2 to 3 percent body weight using hour water deprivation studies Ship and Fischer, , One study determined that salivary osmolality increases during exercise in the heat accompanied by modest 2. Body weight changes are frequently used to estimate sweating rates and therefore changes in total body water e. This approach is usually used to estimate changes over a relatively short duration when food and fluid intakes and excretions are carefully controlled.
The validity of this estimate depends upon body weight measurements not being confounded by other nonfluid factors that can influence body weight changes. If proper controls are made, body weight changes can provide a more sensi-. Potential confounding effects of urine loss, fluid intake, respiratory water loss, metabolic mass loss, water trapped perspiration in clothing on sweat loss, and therefore total body water change estimates for individuals performing exercise in hot and cool conditions have been examined Cheuvront et al. Significant errors in estimating sweating rate are introduced unless nonperspiration fluid losses are factored into the body weight changes Cheuvront et al. Likewise, carbohydrate loading in athletes will result in elevated baseline body weights that do not reflect euhydration, as the muscle glycogen will osmotically hold water.
Overall, body weight changes provide an effective index of body water changes if other factors influencing body weight are carefully controlled. Various scales have been developed over the years to quantify thirst by rating the sensation of, for example, dry mouth or dry throat. However, the most practical and commonly used approach in animal and human studies has been to document the volume of ad libitum voluntary drinking as a surrogate measurement of thirst.
Despite ad libitum drinking, humans tend to under-replace their fluid needs over the short term Johnson, Triggering of thirst occurs through perceptual and physiological mechanisms Fitzsimons, ; Greenleaf and Morimoto, ; Rolls and Rolls, For example, increases in plasma osmolality, plasma volume reduction, and several thirst sensations all made substantial contributions to predicting ad libitum fluid replacement following water deficits of 3, 5, and 7 percent of body weight loss Engell et al. Voluntary drinking of a beverage is affected by its palatability, which is determined by its color, flavor, odor, and temperature Boulze et al.
These factors. The sweetness of a drink is a major factor in its palatability, but people differ in their preferred flavor. Flavor preference depends on various factors, including ethnic and cultural backgrounds. For example, in one study with Canadian children, most preferred grape to orange or apple flavors and drank more when presented with a. Reprinted with permission, from Wilk and Bar-Or Copyright by the American Physiological Society. In contrast, children in Puerto Rico had no preference for any single flavor Rivera-Brown et al.
Based on studies of various animal species, including humans, there seems to be three main physiological triggers for thirst: cerebral osmoreceptors, extra-cerebral osmoreceptors, and volume receptors Fitzsimons, ; Greenleaf, ; Greenleaf and Morimoto, The osmoreceptors respond to cellular dehydration, which occurs when fluids leave the cells as a result of osmotic forces. The volume receptors respond to extracellular dehydration that results from loss of fluid from the vascular and interstitial spaces. While the osmoreceptors respond to small increases in osmolality, the volume receptors are activated by more drastic fluid losses.
The osmoreceptors, therefore, are considered the first line of homeostatic defense against dehydration. The location of these cells varies among species, but they are concentrated mostly in the hypothalamic area of the brain. Stimulation of the osmoreceptors activates drinking behavior and the release of arginine vasopressin hormone. The latter increases water permeability of the collecting tubules and thereby reduces free water loss and urine volume. There is evidence that either sodium chloride or an increase in osmolality probably through separate cells can activate the cerebral osmoreceptors, but it is assumed that the increase in osmotic forces is the more important stimulus Greenleaf and Morimoto, Similar responses have been described for animals Okuno et al.
Other osmoreceptors located in the oropharynx, gastrointestinal tract, and particularly the liver-portal system respond to drinking and modulate the thirst drive. Their existence has been postulated through experiments in which thirst and arginine vasopressin levels were modulated soon after drinking or after injection of fluid to the liver portal system , before there were any changes in plasma osmolality or volume. Thirst may be triggered by a decrease in blood volume, such as in hemorrhage or severe dehydration. This occurs through volume or stretch receptors that are sensitive to a drop in pressure at sites such.
These receptors, through the vagal system, stimulate thirst and drinking. Because of the compensatory activation of the renin-angiotensin-aldosterone system, preservation of body fluid is also achieved through a reduction in urinary output. Triggering of thirst through hypovolemia requires more than small changes in blood volume. The role of various thirst mechanisms with altered hydration status has been reviewed in detail elsewhere Mack and Nadel, ; Stricker and Sved, However, in almost all situations where smaller volumes are lost over time such as 2 to 3 L of sweat over 6 hours due to high temperatures or exercise , thirst mechanisms come into play over the ensuing 24 hours to trigger replacement of fluids lost; thus, in general, normal hydration is maintained by thirst mechanisms and normal drinking behavior.
Such replacement is enhanced by consuming beverages at meals and in other social situations Engell, ; Szlyk et al. Dehydration can adversely influence cognitive function and motor control. Dehydration and poor mental function have been reported to be associated in physically ill older people Seymour et al. Table summarizes studies that examined the effects of dehydration on cognitive performance and motor function in healthy individuals. Interpretation of these reports is difficult because the experimental designs often do not allow discrimination of confounding factors, such as effect of thermal or exercise stress and that of dehydration per se Epstein et al.
For example, a degradation in mental alertness, associative learning, visual perception, and reasoning ability were noted when healthy men exercised while exposed to a high climatic heat stress Sharma et al. Although the subjects drank water ad libitum , they may not have consumed enough fluids over the 4-hour session and thus became dehydrated due to the exercise and heat stress. However, the possible effect of dehydration on the above mental functions was not addressed. In another study, men and women exercised in the heat for 6 hours to elicit dehydration levels of 2. Faster response time to peripheral stimuli, no effect on response time to central visual stimuli. There was no difference in reaction time in response to central visual cues, but reaction time decreased when the visual cues were given at the periphery of the field of vision during the two dehydration conditions.
Once again, interpretation of this finding is difficult because factors such as climatic heat stress, exercise-related fatigue, and boredom were not removed. In a well-designed study, the arithmetic ability, short-term memory, and visual-motor tracking of 11 men who, on separate days, had water deficits of either 1, 2, 3, or 4 percent of body weight via thermal dehydration were assessed Gopinathan et al.
The subjects had ample rest in a temperate environment once they reached the target dehydration. This design allowed the researchers to observe the effects of dehydration per se , without fatigue or heat stress. This study revealed that a threshold level of 2 percent dehydration is required for deterioration of mental functions. A similar threshold was reported by other investigators Sharma et al. The adverse effects on mental function occurred irrespective of whether dehydration was achieved through exposure to the heat or as a result of exercise Cian et al.
A previous study by the same group suggested that exercise-induced dehydration was accompanied by a greater reduction in long-term memory Cian et al. In conclusion, there is evidence to suggest that water deficits of 2 percent of body weight or more are accompanied by declining men-. The mechanisms for this deficiency have not been elucidated. Body water deficits can adversely influence aerobic exercise tasks Sawka, ; Sawka and Coyle, The critical water deficit and. Table presents a summary of investigations concerning the influence of dehydration on maximal aerobic power and physical work capacity e. In a temperate climate, body water deficits of less than 3 percent of body weight did not reduce maximal aerobic power; however, in hot climates, water deficits of 2 percent resulted in large reductions.
Physical work capacity was reduced by dehydration in almost all examined conditions, with a greater effect when heat stress was also present. In a study of dehydration in children at 1 and 2 percent of body weight loss, a greater increase in core body temperature than would have been expected to be observed in adults exercising in hot weather was noted Bar-Or et al. Therefore, children may have greater adverse performance effects from the same extent of dehydration during heat stress than do adults. The effects of body water loss on endurance exercise performance in 13 endurance exercise studies have been reviewed Cheuvront et al. Based on these studies, dehydration appears to alter cardiovascular, thermoregulatory, central nervous system, and metabolic functions.A scheme that shows a chemical Potassium Chloride Lab Report may also show possible intermediates. Please note that Potassium Chloride Lab Report should not physically assemble your Comparing Oedipus To Creon Potassium Chloride Lab Report this order. Archived from the original on 13 August