BIL 360: Class Notes 4 (on final)
BIL 360: Class Notes 4 (on final) BIL 360
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Ch 24 Transport of Respiratory Gases 12032014 NOT ON EXAM 3 PUSHED BACK TO FINAL External respiration how gases OZC02 cross gas exchange membrane bw external environment and internal tissues 0 02 in solution in blood relatively low 0 How do animals carry all the 02 we need to bloodstream 0 Respiratory pigments hemoglobin incr the 02carrying capacity of the blood In 1L blood leaving adult human lungs there s 200mL of 02 bound to hemoglobin 4mL of 02 in solu l 50x incr of 02 Chemical Properties of Respiratory Pigments 4 chemical categories of respiratory pigments o Hemoglobin o Hemocyanins o Hemerythrins o Chlorocruorins Respiratory pigments undergo reversible combination with molecular oxygen 02 o All are metalloproteins o All are strongly colored at least some of the time 0 Many similarities to enzymes but don t alter their 02 ligand Hemoglobins many functions 02 carrying capacity buffers transport storage etc o Alterations of protein structure affect function properties Vertebrate blood hemoglobin 4 units 2 alphaglobins 2 beta globins Heme metalloporphyrin with iron 0 Associated with a globin protein Hemoglobin varies bw tissues 0 eg blood hemoglobin vs muscle myoglobin Hemoglobin varies over the life cycle 0 eg fetal vs adult hemoglobin Multiple forms of hemoglobin may coexist in an individual 0 eg multiple hemoglobins in poikilothermic sh Hemoglobins widely distributed throughout the animal kingdom and are only respiratory pigments in vertebrates o Invertebrate hemoglobins often large multiunit molecules dissolved in circulatory uids 0 Vertebrate hemoglobins located in red blood cells Hemocyanins Found in arthropodsmolluscs 2ncl most common class of respiratory pigments contain copper bright blue when oxygenated Chlorocruorins Marine annelid worms quotgreen hemoglobinsquot Contain iron Greenish cast Hemerythrins Assorted taxa Contain iron bound directly to protein Reddishviolet when oxygenated II The OZbinding characteristics of respiratory pigments The oxygen equilibrium curve 0 Respiratory pigment saturated when 02 partial pressure high enough that all binding sites are oxygenated 0 At saturated adult human blood carries 20 mL 02100mL blood 0 Oxygen equilibrium curve can also be shown using blood oxygen concentration P02 of venous blood at rest 53 kPa o 5mL 02100mL blood released to tissues 0 25 02 utilization P02 of venous blood during exercise 27 kPa o 02 utilization rises to 65 or higher 0 P02 in alveoli 133 kPa P02 of blood leaving lungs 12 kPa Increasing 02 conc of blood systemic tissue during exercise lt systemic tissues at rest lt lungs 0 Rest and exercise decr 02 blood conc in lungs 02 released to tissues by each 100mL of blood Shape of the 02 equilibrium curve depends on 02binding site cooperatively Myoglobin contains single O2binding site each binding site funcUonsindependenUy As P02 incr myoglobin approaches saturation o Hyperbolic relationship Vertebrate blood hemoglobins have 4 02binding site which show cooperativity binding at 1 or 2 of the sites enhances affinity of remaining sites for 02 o Sigmoidal relationship Cooperativer affects oxygenation and deoxygenation of respiratory pigments At midrange partial pressures pigments showing cooperatively will deoxygenate more readily than pigment wo At partial pressure of 02 below saturation diff in affinity allows for transfer of 02 from hemoglobin to myoglobin o bc of partial pressure hemoglobin wants to give up 02 and myoglobin wants to pick uphold on Respiratory pigment s affinity for 02 how readily combined with O2 0 low affinity requires high P02 for loading and unloading at high P02 0 high affinity load fully at low P02 and requires low Po2 for unloading o lowering O2 affinity shifts O2 equilibrium curve to right 0 pigment with lower affinity less saturated with O2 Bohr effect decr pH or incr Pc02 lowers O2 affinity 0 Will also shift curve 0 Decrease in pH increase in acidity o Incr in Pc02 decreases hemoglobin affinity for O2 Bohr effect is highly adaptive for 02 delivery 0 Respiratory pigment can shift to lower 02 affinity more likely to release 02 when in systemic tissues when returns to lungsgills shifts to higher affinity o pHC02 important during exercise 0 produces C02 get higher Pco2 drives curve to right 0 C02 reacts with water to form carbonic acid Exercise generates acid metabolites lactic acid Decreases pH 0 increasing temp also decreases 02 af nity conditions generated in body tissues favor release of 02 from hemoglobin to tissues where it s needed Ill Carbon Dioxide Transport 0 Carbon dioxide dissolves in blood as C02 molecules but quickly undergoes rxn with water to form carbonic acid l bicarbonate H 0 C02 acts as gaseous acid in aqueous systems bc includes protons Blood buffers determine how much CO2 blood can hold in the form of bicarbonate When H ions increase buffers return to equilibrium by production of bicarbonate 0 At equilibrium 0 Liquid with no CO2 dissolved in blood bring into contact with C02 gas partial pressures will equalize 0 Now have some partial pressure of CO2 in solution 0 Relative concentrations related by equation At a given conc of CO2 Pc02 constant K value also constant Means that amt of bicarbonate formed depends inversely on amt on H conc At H increases HCO3 decreases 0 But if buffers remove H from solution H will remain low and CO2 will react with water to form HCO3 o Bicarbonate is how blood takes up 02 Buffer rxns represented by equation HX ltgt H X 0 When H added to buffered solution drives equation to left 0 When H removed from solution drives equation to right Buffers in animal blood found on blood proteins including hemoglobin o Buffers really good at removing H lowers H drives production of HCO3 C02 concentration represented by the C02 equilibrium curve 0 Total C02 conc includes 0 Dissolved C02 0 HCO3 o Carbamate groups NHCOO Shaped determined by how much bicarbonate formed thus depends on buffer system Haldane effect C02 equilibrium curve changes with deoxygenation of respiratory pigments Respiratory pigments act as buffers 0 Determine how much HCO3 formed 0 How well they buffer depends on deoxygenation Deoxygenation causes incr in H uptake 0 Lower H l formation of more HCO3 l incr in blood C02 0 Fully oxygenated blood arterial blood 0 More 02 lower ability to hold C02 in form of bicarbonate Deoxygenated blood Venous blood 0 Less 02 forms bicarbonate Circulation Pressuredriven bulk ow of uids Transports gases nutrients wastes hormones immune agents and heat Provides hydraulic pressure for organ function I Hearts 0 Discrete localized pumping structures 0 May be singlechambered or multichambered 0 Animals may have auxiliary hearts 0 Right side responsible for receiving deoxygenated blood and pumping blood to lungs Left side responsible for receiving oxygenated blood from lungs and transporting to body The heart is a pump Contraction systole Relaxation diatole Cardiac output the volume of blood pumped per unit of time 0 Cardiac output mLmin heart rate beatsmin x stroke volume mLbeat The circulation must deliver 02 to the myocardium 2 principle types of myocardia 0 Compact myocardium supplied with blood via coronary circulation o Spongy myocardium obtain 02 from blood in ventricular lumen Mammals and birds 0 Compact myocardium with coronary arteries and veins Teleost sh amphibians reptiles o Spongy myocardium with littleno development of coronary vessels Some sh amphibians reptiles o Myocardium composed of outer compact tissue and inner spongy tissue Some octopus o Myocardium of mixed structure with blood owing from lumen into coronary veins Electrical impulses for heart contraction Rhythmic contractions set by heart s pacemaker lmpulses to contract may be neurogenic or myogenic vertebrates SA node Depolarization spreads via conduction A heart produces an electrical signature the electron cardiogram process of depolarization of the myocardium creates ionic currents in muscle and surrounding tissues ECGs measure voltage differences over time o P depolarization of atria o QRS depolarization of ventricles o T repolarization of ventricles ll Principles of Pressure Resistance and Flow in Vascular Systems Perfusion forced ow of blood through blood vessels 0 Blood pressure produced by heart is principal factor causing blood to ow 0 Pressure measured in kilopascal kPa or mmHg 0 Blood pressure uctuates in arteries Systolic pressure highest pressure during heart contraction n In young adults 120 mmHg Diastolic pressure lowest pressure during heart relaxation a 75 mmHg typically referred to as systolicdiastolic 12075 Blood pressure also comes from uidcolumn effects hydrostatic pressure 0 depends on height mass density of uid and gravity 0 blood pressure above the heart is lower blood pressure below the heart is higher The rate of blood ow depends on differences in blood pressure and vascular resistance HagenPoiseuille equation 0 Flow rate Pin Poutpi81nrquot4l o lncr pressure change incr rate of ow 0 lncr viscosity decr rate of ow 0 lncr radius incr rate of ow III A Circulation in Mammals and Birds Lungs placed in series with systemic tissues Maximizes efficiency of 02 delivery to tissues 0 Closed circulatory system 0 Independent evolution in birds and mammals Each part of the vascular system has distinctive anatomical and functional features 0 Arteries 0 Thick walls muscle connective o Convey blood under high P 0 Elastic Arterioles 0 Same basic structure as arteries 0 Vasomotor responses Capillaries 0 Single layer of vascular endothelium 0 Site of exchange Venules o Receives blood from capillary beds 0 Small thin walls muscle connective o Veins 0 Lower BP in returning blood 0 All vessels lined with vascular endothelium III B Circulation in Fish 0 Fish have a close circulatory system breathing organs placed in series with systemic tissue 0 Potential problems in circulatory plan of sh 0 1 no heart bw breathing organ circulation and systemic circulation o 2 oxygenation of myocardium depends fully or partly on 02 from blood owing thru lumen but already relatively deoxygenated III C Circulation in Amphibians and Reptiles 0 Most amphibians and reptiles have undivided or incompletely divided ventricle but are capable of selective distribution of oxygenated and deoxygenated blood 0 Amphibians skin oxygenates blood returning to heart 0 Likely provides 02 to myocardium Crocodilians have completely divided ventricle IV A Invertebrates with closed circulatory systems 0 Closed systems found in some annelids and cephalopod molluscs o Cephalopod molluscs have principal systemic heart and 2 auxiliary branchial hearts 0 Generally resembles mammalian avian and sh plans IV B Invertebrates with open circulatory systems 0 All arthropods and most molluscs exhibit open circulatory systems Lacunae small spaces among cells of systemic organs tissues Sinuses larger blood spaces serving as thoroughfares for blood 0 Hemolymph Fluorescentdyed blood in leg of spider rst travels thru discrete vessels then ows out thru lacunae and sinuses Ex decapod crustaceans o Singlechambered heart 0 All vessels l arteries 0 Suspensatory ligaments pericardinal sinus ostia 0 Though structurally different open systems may be functionally equal to closed systems I Water and Salt Physiology Intro Importance of animal body uids 0 Body uids Represent majority of body weight in many animals 0 Intracellular uids 0 Extracellular uids Interstitial uids Blood plasma Body uids composed of water inorganic and organic molecules All animals have evolved speci c relations of their body uid composition to the external environment 3 major body uids of an animal interact and affect one another intracellular uid interstitial uid blood plasma 0 exchange of water and ions across cell membrane intracellular interstitial exchange of water and ions across capillary endothelium interstitialblood plasma Types of regulationconformity Osmotic regulation maintains constants osmotic pressure bw internal and ambient environments 0 Osmotic conformation internal osmotic pressure changes with respect to ambient osmotic pressure 0 Green crab imperfect regulator at low osmotic pressure conformer otherwise 0 Ionic regulation maintains ion concentrations 0 Volume regulation maintains constant volume 0 Regulation 0 Bene ts cells because provides constant conditions for cells 0 But is energetically costly ll Regulation of watersalt in natural environments Natural aquatic environments 0 Animals surrounded by water 0 Key factor for determining environment s challenges salinity measure of total conc of all salts dissolved in water Seawater high salinity 3436gkg of water 0 Freshwater low salinity gt05gkg 0 Ion conc always fairly dilute in freshwater but vary bw different bodies of freshwater 0 Calcium hard water has higher conc than soft water Can affect membrane permeabilities of cells 0 Brackish water intermediate salinity o Osmotic pressure and ion conc vary spatially and temporally o Chesapeake bay Temporal changes a Long term in spring snow in mts melts lowers salinity a Short term High tide raises salinity in bay Estuaries very important but difficult to live in bc there is very large variation in salinity difficult to regulate water and salt Natural terrestrial environments Surrounded by air with gaseous 02 water vapor Key factor evaporation Evaporation a special case of gas diffusion 0 Water vapor pressure is partial pressure of water vapor 0 Water diffuses from highow water vapor pressure 0 Evap Only occurs if partial pressure of body greater than ambient Rate of evap Depends on the size of the difference Saturation max water vapor pressure in air of a given temp o Increases beyond this lique es into water droplets fog Water vapor pressure depends on temp solute conc 0 At high temp l Terrestrial animals tend to lose water to atmosphere 0 Are warmer than ambient 0 Respiratory have moist membrane exposed to air Organs of blood regulation 0 Animals experience conditions that tend to change their blood composition 0 O O Organs like kidneys act to reverse change Do so by removing solutes from blood Some animals use gills Birdsreptiles have salt glands Kidneys are blood plasma ltrators release excess solutes in urine 0 O O O 0 WP ratio an index of the action of the kidneys Osmotic UP osmotic pressure of urineosmotic pressure of plasma UP 1 isomotic urine urine and plasma have equal osmotic pressure UP lt hyposmotic 1 urine has lower osmotic pressure increases osmotic pressure of plasma UP gt hyperosmotic a urine has greater osmotic pressure decr osmotic pressure of plasma 0 Animals of diff species regulate diff UP ratios The UP ratio helps us understand osmoregulation Solution A hyperosmotic water moves towards A o Freshwater sh 0 O O O 0 Blood plasma hyperosmotic to surrounding water Tends to gain water by osmosis Blood will decr in osmotic pressure UP1 isosmotic urine will not return blood to original levels still taking on water from environment UPlt1 hyposmotic urine will aid osmoregulation avoid taking on excess water Terrestrial animals if plasma osmotic pressure too high 0 Want to retain water don t release in urine 0 UPgt1 hyperosmotic urine will aid in osmoregulation plasma Volume regulation depends on amount of urine 0 In addition to osmoregulation kidneys helps regulate volume of water in body 0 Volume regulation has distinct function separate from osmoregulation 0 Don t necessarily occur together 0 Blue crabs freshwater 0 Water taken in by osmosis 0 Produce isosmotic urine UP1 Urine production voids excess volume but doesn t contribute to osmoregulation Ionic regulation depends on ionic UP ratios 0 Can be measured with osmoregulation Ionic UP ratios for each ion in body uids 0 Sodium UP ratio UrineNaPlasmaNa 0 Each ion distinct from each other 0 Marine teeost sh blood hyposmotic to seawater o Tend to lose water osmosis gain ions diffusion Raises osmotic pressure and ion conc of plasma 0 Produce isosmotic urine UP1 Produce urine with ionic UP ratio gt 1 Mg2 Ca2 etc Urine production voids excess ions but doesn t contribute to osmotic regulation Ingest food and water can have implications for an animal s watersalt physiology Marine teleost hyposmotic Marine inverts isosmotic with seawater have similar osmotic pressures o If animal feeds on marine inverts consume a lot of salt Salty plants in humid environments salt accumulates in halophytes plants that live in high salinity soils 0 Most animals cannot eat these plants 0 Sand rats have special adaptations in kidneys to compensate for extra salt content Protein rich meals 0 Protein made of AAs large amounts of N o Catabolism results in nitrogenous waste 0 In mammals nitrogenous waste excreted in urea requires a lot of water to ush out Salty drinking water 0 Makes body lose more water than taken in from drinking salt water Ingest chloride can only get rid of by excreting excess water Void water ingested and excess body water dehydration 0 Some animals can drink salt water depends on how well they excrete salts and retain water 00 Metabolic water animals produce water thru aerobic catabolism Preformed water water that s ingested Metabolic water production a stoichiometric function depends on how many molecules of food consumed bc water produced during aerobic catabolism doesn t mean that body will take in water in net fashion doesn t mean animals gain water 0 bc also results in obligatory water losses o obligatory respiratory water loss magnitude depends on species physiology and humidity of ambient air more humid l less evap o Obligatory urinary water loss usually cause by high protein consumption require extra water to ush out high N waste product 0 Obligatory fecal water loss only occurs when food metabolized lngested food usually have some preformed water Differences in importance of metabolic water depend on animal s ecology and waterconserving adaptations Compare lab rats and kangaroo rats in same conditions 0 Lab rat evolved in temperate conditions 0 Kangaroo rat evolved in very aired conditions 0 Find that kangaroo rats survive well lab rats will die if not given water 0 Give same amt food both making same amt metabolic water Kangaroo rat 0 Lower urinary water loss bc kidney more efficient 0 Make drier feces 0 Get net gain of metabolic water Lab rat 0 Water losses in urinary and fecal 0 Get net loss of metabolic water Not a difference in metabolic water production but conservation I Animals in freshwater Freshwater animals descended from oceandwelling ancestors Freshwater animals hyperosmotic regulators Passive water and ion exchanges freshwater animals tend to gain water by osmosis and lose major ions by diffusion Energetic costs of regulation depends on rates of passive exchange 0 Rates affected by 1 bloodenvironment gradients 2 permeability 3 surface area Osmotic and ionic gradients o Freshwater animals have lower osmotic pressures than marine Low blood osmotic pressure decr the gradient bw body uids and environment Permeabilities o Freshwater animals have integuments with low permeability to reduce passive exchange 0 Most passive exchange occurs across the gills Regulatory mechanisms of freshwater animals urine Freshwater animals void excess water gained by osmosis by producing large amts of dilute urine hyposmotic to blood UPlt1 Kidneys limit ion in urine but still a loss of ions 0 Volume regulation in con ict with ion regulation Regulatory mechanisms of freshwater animals active ion uptake 0 Freshwater animals actively take up major ions from water simultaneously remove metabolic wastes Exchange of ions pumps are electroneutral ll Animals in the ocean Some marine animals have completely marine evolutionary history 0 Others have ancestors who moved to freshwater and land followed by reinvasion of marine habitats Marine invertebrates Body uids of most marine inverts are isosmotic to seawater Species tend to differ from seawater with respect to particular ions 0 Hag sh primitive jawless sh 0 Only vertebrates with exclusively marine ancestry 0 Similar in osmotic and ionic relations to marine inverts Marine teleost sh 0 Modern marine teleost sh likely descended from line that moved from oceans l freshwater l oceans Marine teleosts hyposmotic regulators Body uid osmotic pressures o gt freshwater teleosts o lt marine inverts replacement of water losses 0 To replace water lost by osmosis teleost sh drink water 1 ingestion of hyperosmotic seawater causes diffusion of body water into seawater in gut 2 in later parts of gut a Na and Cl actively transported out of gut and into blood n Favors osmotic uptake of water into blood 0 Marine teleost sh excrete excess divalent ions in urine 0 O O 0 Passive process drinking seawater ions incr in blood Divalent ions l excreted in urine Monovalent ions l excreted by gills Excreted urine is isosmotic to plasma osmotic UP1 Ionic UP ratios Monovalent ions lt 1 Divalent ions gt 1 lonic regulation via urine production con icts with osmoregulation teleost sh limit urine production 0 Extrarenal NaCl excretion by gills O O O O O O Na Cl and nitrogenous wastes voided across gills NaK pump creates electrochemical gradient favoring Na diffusion l cell Na diffuse into cell at NKCC with K and 2 Cl Cl entry creates gradient favoring outward diffusion via Cl channeb Excretion of Na may be active or passive Fish excrete NaCl wo water gills primary site of osmotic regulation Freshwater teleosts Hyperosmotic to surroundings take on water lose ions 0 Active uptake on ions at gills Produce dilute urine Marine teleosts Hyposmotic to surroundings lose water take up ions Ingest seawater Excrete ions in urine and across gills Marine reptiles birds mammals hyposmotic regulators Many of adaptations for terrestrial life in these groups also aid osmotic regulation in marine habitat ln reptilesbirds kidneys produce urine isosmotic to blood 0 Excess salts excreted externally via salt glands Mammals produce concentrated urine 0 Not exceptional to terrestrial counterparts in urine concentrating abilities 0 Much unknown about marine mammal saltwater balance Marine elasmobranch sh hyperosmotic but hypoionin to seawater Maintain low blood conc of Na and Cl 0 High conc urea and TMAO Hyperosmotic but hypoionic to ambient water 0 Rectal glands secretions rich in NaCl and salts and water in feces o Modest amts of urine modestly hyposmotic to plasma rich in Mg2 and SO42 Roles of gills in salt excretion are uncertain Salt gain by diffusion across gills Water gain by osmosis across gills Saltswater in food generally don t drink OOOO Review Freshwater hypoosmotic 0 Take on too much water Produce a lot of isosmotic urine a lot of water few ions 0 Lose salts and ions by passive processes Have special active pumps in gills to take up ions from environment 0 Descended from marine animals 0 Marine 0 Where life began most diversity of animal phyla o Invertebrates isosmotic Salty body uids same conc as surrounding uids 0 Teleost sh hyposomotic Evolutionary history oceans l freshwater l ocean I Ancestors were freshwater evolved lower body uid osmotic uids Hyposmotic maintain osmotic pressure lower than surrounding water Losing water to environment a Drink seawater Take up ions bc body ion conc lower than surroundings concentrates body ions I Use kidneys to excrete divalent ions n For monovalent ions released thru gills extrarenal excretion outside kidneys o Reptiles birds mammals Evolution ocean l fresh l were once terrestrial l ocean Hyperosmotic worry about drying outlosing water I Have more impermeable skin helps in marine environment bc don t lose water regularly I Breathing respiratory exchange membranes not coming into direct contact with seawater If they eat very salty food must get rid of n Mammals super kidneys high concentrating ability to get rid of ions In Birdsreptile salt glands extrarenal Ill Animals that face changes in salinity lncludes animals that migrate long distances 0 Ex salmon migrate from fresh to saltwater habitat to fresh for breeding lncludes animals that live near coast estuaries and salt marshes 0 Ex cheasapeake bay changes constantly Stenohaline narrow range of salinities 0 Marine mammals Euryhaline wide ranges in salinities 0 Marine osmoconformers euryhaline Very adaptive cessile organisms in intertidal zone can t move so need to deal with wider ranges of salinities Osmoconformers permit blood osmotic pressure to vary with environment Osmoregulation maintain stable blood osmotic pressure as environment changes Osmoregulators o Hyperisosmotic regulators at low salinity hyposmotic regulators at high salinity are isosmotic regulators Many marine inverts o HyperHyposmotic regulators at low salinities are hyperosmotic at high salinities are hyposmotic at high salinities Crustaceans and migrators Migratory sh are exceptional osmoregulators 0 Look like freshwater teleosts in fresh and like marine teleosts in saltwater Salt exposure is a trigger for change induces phenotypic changes 0 What ion proteins in gill membranes 0 Aquaporin levels 0 Ex brown trout start in freshwater transferred to seawater for 60 days then returned to freshwater 0 Looking at 2 diff ion pumps and how they are regulated o NaKATPase o NKCC Have more in seawater than fresh 0 Seawater hyposmotic regulators lncr levels of active ion transporters Have extrarenal excretion Gets rid of ions 0 Freshwater hyperosmotic regulators Lower levels of ion transport proteins because not excreting ions Aquatic animals that face drying of their habitat Ephemeral water source habitat of some animals can dry out puddles tidal pools Ex lung sh burrow into mud form cocoon live on stored energy until conditions improve Anhydrobiosis to remain alive wo water 0 Survive while dried as much as possible by air 0 Spring back to life when they hit water Rotifers water bears IV Animals on Land Fundamental Principles Terrestrial animals evolved from aquatic ancestors 0 Left water bene ts from no competition and lack of predators o Faced with challenge evaporative water loss Focus on water balance 0 2 major categories WRT their water balance 0 Humidic animals live in wet environment Worms amphibians terrestrial crabs slugs Spend life near water or in wet environment Amphibians still need standing water 0 Xeric animals live in dry water poor environments Birds mammals reptiles arachnids Some can live in desert o Distinction bw 2 how fast they dry out 3 ways terrestrial animals lose water to the environment 0 evap across integument outer body covering 0 evap during respiration o excretion Evaporative water loss across integument rate of evap water loss across integument depends on 0 water vapor pressure of body uid vs air 0 permeabilties of integument Humidic animals 0 Highly permeable integument high evap loss 0 Reduce water loss by living in humid habitats decr water pressure gradient bw body and air Xeric animals 0 Lower integument permeability 0 Have microscopic lipid layers to reduce evap loss Cells have a lot of keratin and structural proteins with intracellular lipids that prevent water from crossing Respiratory water loss depends on breathing organs and metabolic rate respiration across skin 0 amphibeans invaginated lungs o terrestrial animals 0 can also have evap water loss from mucus membranes during respiration colder air lower water vapor pressure 0 when mammalbirds inhales air incr air temp air becomes saturated with water from the animal 0 if that air exhaled would take all that saturated water with it 0 but when air exhales thru nasal passages cools air lowers saturation 0 working in a countercurrent process depends on ow of air in opposite directions as air goes thru respiratory passages gets warming takes on water air passages themselves become cooler and drier n so nasal passages cooled as air exhaled thru nasal passage warm moist air moves out encounters increasingly cooler temps reduces air saturation o more pronounced in dogs cold nose evaporative water loss EWL integumentary and respiratory losses together form an animal s total rate of evap water loss allometric relationship bw body size and weight speci c evap water loss 0 bc surface to volume ratio high in larger animal more surface area to lose water from 0 small animals have higher weight speci c MR rates more water loss from respiration Phylogenetic groups differ in rates of EWL o Amphibians have very high EWL o Lizards have very low EWL bc don t have skin breathing invaginated breathing o Mammalsbirds in middle bc have higher MR l higher respiratory EWL Within group dryadapted species better avoid EWL 0 Desert iguana and normal iguanas Excretory water loss terrestrial animals minimize urinary water losses via 0 concentrating urine decr amt of water needed to excrete wastes o reducing solutes excreted in urine urine concentration 0 mammals o urine is isosmotic to body 0 humans have UP 4 o camels UP 8 o desert hopping mice UP 26 urine solutes o uric acid urate salts guanine poorly soluble voided wo water produce insoluble N waste product so don t need water to void reptiles birds white waste 0 urea ammonia water soluble require water for excretion humidic animals mammals kidneys produce highly conc urea terrestrial animals differ in water turnover rates inject animals with heavy water then measure how much left after some time high rates of water turnover animals loses and replaces lots of water o precarious bc if imbalance in water lossgain o birdsmammals have higher rates of water turnover than similar sized reptiles 0 within group smallerbodied animals have higher rates of water turnover 0 high MR l higher water turnover rate Case study Amphibeans Have wide range of habitats live near water but also have desert toads Water challenges 0 Permeable integument o Urea is N waste product urea highly soluble needs water to be released 0 lsosmotic urine can t produce urine more conc than body uids 0 Hormonal control of antidehydration by ADH 0 Reduced rate of urine production lncr urine conc o Reuptake of water from bladder lncr level of aquaporins Terrestrial amphibians have larger bladders 0 Water uptake thru ventral skin Skin takes up water from environment Have ventral patch that they press up against wet things and take up water Behavioral adaptations for desert amphibians o Nocturnal 0 Live in protective microhabitats burrows 0 Seasonal dormant spadefoot toads Case study Xeric Invertebrates desert ants Xeric invertebrates display 0 Integuments highly resistant to water loss 0 Limitation of respiratory water loss Can close off portions of respiration to reduce EWL o Excretion of waste N is poorly soluble forms Guanine more solid waste product 0 Production of conc urine 0 Desert ants exposed to heart of day while scavenging for other insects who die from the heat 0 Must recover bodies before they dry out so must leave burrows during middle of day 0 Long legs incr height from surface reduce body temp by 10C Can also climb up on pebbles 0 Can tolerate very high temps 0 Can die from heat if they are not fast Remarkable navigation Case Study Xeric vertebrates lizards and small mammals 0 Both obtain preformed water in diet 0 bc drinking water may not always be available Chuckwalla Low MR reduce water loss and food needs 0 Excrete N wastes as uric acids urates Don t require a lot of water for excretion o Behavioral avoidance Shady areas Salt glands 0 Can survive high plasma Can survive high conc solutes during dehydration much longer than mammals could Roundtailed ground squirrel 0 Higher MR l respiratory water loss but lower rates than non desert relatives Small desert animals evolved lower basal MR than similar sized species in normal environment 0 Behavioral avoidance 0 Daily torpor Water budget of a kangaroo rat 0 Were fed grains and no water 0 Water losses 0 Evap losses decr with incr humidity 0 Urinary fecal losses relatively constant 0 Water gains 0 Metabolic water constant dependent on MR 0 Total input incr with humidity preformed water in airdried grain food 0 O Kangaroo rats remain in water balance if total water inputs equalexceed water losses I Basics of Kidney Function Aquatic animals have kidney and gills for maintaining composition of body uids Terrestrial animals only have kidneys Kidneys are diverse in morphology and physiology 1 have tubular structures opening to outside world 2 produce and eliminate solutions derived from blood or extracellular uid 3 function to regulate body uid volume and composition by controlled excretion of water and solutes 0 does so by getting rid of wastes thru urine The product of kidneys is urine N waste inorganic ions organic compounds water Excretion or urine serves many function simultaneously Primary formation occurs in 2 basic steps Primary urine introduced to tubules modi ed as it move thru tubules becomes de nitive De nitive urine urine excreted by body Primary urine formed by ultra ltration in most verts o Lumen of capillary and lumen of Bomans capsule separated by only 2 cell layers 0 Blood pressure drives plasma uid across quot lterquot capsular uidprimary urine Kidneys have many tubules nephrons when modi cation of urine takes place 0 Each nephron ends in hemispherical envaginated structure bomans capsule win each have network of blood capillaries close juxtaposition bw blood and nephron o renal corpuscle entire structure 0 uid driven across lter layer of epithelial cells into bomans capsule primary urine is this ltered body uid hydrostatic pressure and colloid osmotic pressure combine to form net ltration pressure higher osmotic pressure in blood favors diffusion back into blood hydrostatic pressure bw the 2 higher in arteries favors water ow of blood into capsule drives bulk of water ow into capsule glomerular ltration rate GFR primary urine formation in verts o humans 120 mmin 123Lday very high 0 this is the about ltered into primary urine not what is excreted 0 so a lot is reabsorbed before urine can vary rate in nephrons or regulate how many nephrons working 0 main way reabsorbing diff levels of water major regulatory processes occur after primary urine formation as primary urine ows thru tubules and other parts of excretory system de nitive urine 0 regulating composition of body uid and blood plasma happens in de nitive urine 0 see diffusion of ions osmosis o in some animals have other processes basics kidneys regulating blood plasma composition and volume water and solutes diffuse bc capillary closely juxtaposed uid driven by hydrostatic pressure from blood pressure 0 further modi cation for regulation ll Urine Formation in Amphibians Generalized vertebrate nephron A each nephron has bomans capsule convoluted segment proximal convoluted tubule intermediate segment distal convoluted tubule collecting tubule to collecting duct that carries urine to bladder B nephrons microscopic in diameter macroscopic in terms of length 0 10005 found in each kidney make up much of kidney 0 collecting tubules of all nephrons feed into collecting ducts that all connect at urinator kidneys lter more watersolutes than excretes have access to regulating most watersolutes must be reabsorbed reabsorption begins in proximal convoluted tubule isosmotic 0 active uptake of NA glucose out of primary urine 0 passive reabsorption of CL water follows path of Na creates electrical gradient Cl can follow water moves simultaneously keeps it isosmotic with blood 0 have continuous conc o reabsorption of glucose small enough to go thru lter 0 more regulation in distal tubule o reabsorb watersolutes differentially to change conc Na still being reabsorbed Presence of ADH determined water reabsorption o osmotic pressure and composition changes more regulation occurs in distal convoluted tubule differentially reabsorbed watersolutes in production of de nitive urine distal tubules control excretion of osmotically free water pure 0 have water required to accompany wastes to be excreted 0 also have additional water that s not necessary for excretion osmotically free water 0 max possible UP ratio 1 0 so urine osmotic pressure cannot exceed osmotic pressure if urine has no osmotically free water UP 1 WP lt 1 l excreting extra water more dilute urine animals can control exception of water by varying osmotic pressure 0 manage with diff levels of ADH antidiuretic hormone prevent loss of free water in urine 0 low ADH diuresis abundant urine low permeabilities to water water remains in tubule water excreted UP lt 1 ADH important for insertion of aquaporins little ADH l few aquaporins low permeabily little water leaving tubule 0 High ADH antidiuresis OOO Induces wall of tubule to become more permeable to water by incr of aqauporins Low urine volume High permeability to water Water reabsorbed Urine concentrated UP 1 0 Also reduces glomarial rate by reducing number of active nephrons o Amphibians can have further regulation managed by ADH Ill Urine formation in mammals Mammalian kidneys characterized by gross structure presence of loops of Henle Nephron of mammal have extra long tubules arranges in loop loop of Henle 0 Loop can differ in length varies with species Loops of Henle and collecting duct arranged in parallel allow for production of urine that s hyposmotic to blood 0 Bomans capsule in cortex near outside of kidney Loops of Henle 2 long parallel tubes 0 descending limb uids owing down 0 Ascending limb uid owing up and into collecting duct 0 Collecting ducts located in interior of kidney Fluid moves thru proximal to decending limb returns back of ascending limb to collecting duct then to outer part of kidney again Loops of Henle can be 0 Long 0 Short if they turn back within outer portion of medulla or in cortex Loops of Henle important for producing hyposmotic urine 0 Renal papilla region of medular that projects into renal pelvis 0 contain long loops of Henle o more developed in aridadapted species 0 aquatic species have little development 0 Relative medullary thickness correlated with urinary concentrating ability 0 Correlates with length of loops of Henle o lncr medulla thickness with incr ability to concentrate urine Urea solute Na K Cl Deeper into kidneymedulla uids around loops of Henle very salty Lower salinity of uids around outer tubules of kidney Countercurrent multiplication key to producing concentrated urine 0 Water removed from urine as it passed thru collecting ducts Water leaves collecting ducts via osmosis during antidiuresis due to high slat conc in medullary interstitial uids 0 Salt conc generated by loops of Henle Single effect 0 A initial condition 0 All uids isosmotic same osmotic pressures B processes that generate the single effect o Ascending limb active transport of NaCl Impermeable to water interstitial uid osmotic pressure incr Raises osmotic pressure and solute conc o Descending limb more permeable C single effect 0 Ascending limb low conc of solutes o Fluid of descending lim high conc of solute A the single effect and the endtoend gradient generated from it by countercurrent multiplication Single effect amounts to an osmostic difference of 200 mOsm from side to side of the loop of Henle Countercurrent multiplier system provides an endtoend dif of 600 mOsm or more for some animals 0 Lower osmotic pressure up high Countercurrent multiplier system 0 1 lsosmotic 2 lncr osmotic pressure in both limbs single effect 0 3 More conc high osmotic uids in descending uid 0 new primary urine moving in at 300 o uid that was concentrated now moved into ascending limb 4 lower conc and osmotic pressure along ascending limb o incr gradient 0 interstitial uid at bottom very high interstitial uid develops increasingly incr osmotic pressure at end of loop o generates salty interstitial uids 0 favors reabsorption of water from collecting ducts antidiuresis countercurrent system multiples effect of single effect consequence of countercurrent multiplier renal tissue and blood becomes increasingly more hyperosmotic in deeper regions of kidney 0 highest osmotic pressure in inner zone of kidney medulla Excretion of concentrated urine antidiuresis 0 Yellow walls impermeable to water 0 Antidiuresis have impermeable collecting duct 0 Length of loop of Henle determine how salty interstitial uids are 0 Urine leaving loop hyposmotic o Ascending limb pumping ions out but impermeable to water so no exchange causes incr in osmitic pressure 0 ADH inserts aquaporins to incr permeability 0 As uring owing down collecting duct water allowed to move out And experiences every satier conditions in interstitial uid Water tends to leave giving concentrated urine Production of dilute urine diuresis Reducing collecting duct H20 permeability 0 Collecting ducts not permeable no water leaves 0 Active NaCL absorption from collecting duct lumen Mammals can adjust conc and volume of their urine over broad ranges ADH controls switch bw antidiuresisdiuesis o ADH modulates aqauporins in collecting duct epithelium and thus permeability to water
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