Exam III Water Regulation Osmoregulation I Introduction A Life processes are carried out in an aqueous medium Places where water is found Blood serum Cytoplasm of cells Digestive reactions and other enzymatic processes Interstitial water outside cell membranes between cells and losing water at a balanced rate Water gain Water loss B Water balance water taken in water lost must be regulated fairly precisely Component of homeostasis gaining Drinking Eating Metabolic water a product of oxidation of organic molecules C6H12O6 6O2 6CO2 6H2O Product of basic cellular respiration 1 2 3 4 5 Respiration when you breathe air dries out moist tissues Exhaling water vapor from lungs released Urination Kidneys filter blood and take out excess liquids keeps balance N2 byproducts flushed out from blood Defecation depending on species 50 80 water Sweating evaporative cooling Lactation milk is mostly water significant drain II Dealing with dry hot environments A Desert conditions are stressful to the mammalian body water not readily available Can t replace water loss 1 Water loss sweating respiration 1 3 of body weight hr 2 Death occurs when water loss 15 20 of body weight Brain over heats blood gets too thick can t circulate through body B Dealing with very dry environments Take in more water Drink more not an option for most mammals Eat moist food 1 a b Moisture content of food depends upon Type of food I II III Animal Plant less than animal tissue have a lot of defenses Seeds mostly carbohydrates metabolic gain and change in water content depending on environment they re in Animals burrow seeds to pick up moisture more humid environment underground Humidity plants lose water when air is dry humidity of air depends on time of day I Cold weather water vapor will condense on external surface of plant In warm weather water will evaporate out of plant and will be lost to environment Better to eat plant at night because it s picking up extra water through condensation on surfaces with air is colder and can t hold as much water Time of day hygroscopic plants move water within tissues very dramatically Change on daily basis from green and healthy to shriveled up and brown Water contained in leafy greens during night to roots during day Reduce evaporative water loss evaporative water loss sweating and respiration Heat loading camels and desert animals passively gain heat from environment so they don t have to regulate temperature Lower metabolic rate when hot torpor everything goes into slow motion use less energy take in less O2 breathe less frequently lowers water loss Cooler nasal mucosa kangaroo rat lives in the desert so if it exhales normally loses moist air and inhales very dry air As the hot air from the lungs moves through nasal passages loses heat because nasal passages are cooler Some of the moisture from lungs condense on tissues respiratory passages Sets up temp difference between nasal passages and lungs Be nocturnal Be fossorial in the shade cooler very stable temperature buffered from extremes confined space so when water lost through respiration it stays in the space not lost to environment Summer estivation Reduce water excreted in urine 1 1 2 3 4 1 2 3 2 a b c d e f 3 a Urine produced by kidney Excretory product from filtering blood Carries nitrogenous wastes from the body urea uric acid Carries other wastes excess ions vitamins etc Vertebrate urine is normally hypotonic to blood taking water from blood but mammals and birds have the capability to make hypertonic urine very concentrated waste very little water b Basic anatomy and physiology of the kidney composed of repeating tubules loops of Henley Tissues that surround loop of Henley have a varying concentration of ions Longer the loop better at drawing water out of urine making it more concentrated Filtration of blood plasma through glomeruli Active secretion of waste molecules Reabsorption of solutes glucose amino acids and water Final urine concentration depends on the lengths of the loops of Henle Facultative adjustment of the urine concentration depending on level of hydration Mammalian blood plasma 300 mosmols Human urine 1200 mosmols Banner tailed K rat urine 2700 mosmols Oryx urine 2900 mosmols 4000 mosmols Fennec fox urine Vampire bat urine digesting 6000 mosmols 4 5 Bats get rid of a lot of water so they can fly back to roost higher concentration of protein and nutrients Reduce water in feces Reingestion of infant wastes by lactating mothers female gains back water she lost through lactation 1 3 regained Lick offspring to stimulate urination and defecation C Water budget for a desert animal Kangaroo Rat do not drink free water 25 degrees C 20 humidity III Comparison to humans Human Kangaroo Rat Gains Drinking Free water in food Metabolic water Losses 48 40 12 0 10 90 Water losses Water gains Oxidation water 54 0 ml Urine Absorbed water 6 0 ml Feces 13 5 ml 2 6 ml 43 9 ml Total water gain 60 0 ml Total water loss 60 0 ml Evaporation 2 Urine Evaporation Feces 60 34 6 25 70 5 IV Summary of kangaroo rat strategies A A B Animal remains in cool burrow during daytime metabolic water derived from dry seeds respiratory moisture condensed in nasal passages urine concentrated by countercurrent exchange in extralong loop of Henley III Osmoregulation in bats The problem Flying greatly increases level of evaporative water loss Patagium very thin moist skin Flying makes them lose a lot more water through skin than nonflying mammals The solution Urine concentration increases during increased evaporative cooling Roosting in groups in confined spaces results in less evaporative water loss during the day higher humidity in roost Take advantage of increased water vapor in enclosed spaces by huddling together and contributing to increased humidity C Vampire bats Blood meals are high in water and protein Produce dilute urine during feeding Produce small quantities of highly concentrated urine in the roost IV Marine Mammals The physiological desert because not useable water Sea water is hypertonic to blood so drinking seawater means taking in too much salt Only way to get rid of these salts is to take in more water and excreted through urine The problem Both drinking and eating result in an intake of salts that must be flushed out with water A Sea water is hypertonic Most foods are hypertonic except teleost fish B Solutions 1 2 1 2 1 2 1 2 3 Eat teleost fish low in salt don t need extra water to flush out salt Seals sea lions mostly teleost