maintaining a body in a “steady state” homeostasis © cincinnati zoo
TRANSCRIPT
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Maintaining a body in a “steady state”
Homeostasis
© C
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nnat
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Environments where freshwater is scarce:
• Desert• Invertebrates• Reptiles• Terrestrial Mammals
• Ocean• Invertebrates• Fish• Marine Mammals, Turtles, & Birds
• Hypersaline Lakes• Invertebrates
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World-wide distribution of desert environments
•For example Shahara Desert is 3.5 mil sq. miles
•Less than < 3 in. annual rainfall (6.7 cm)
•Habitat: Rocky Plateaus (15%), Sandy Dunes (15%), Gravel Plains (70%)
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Adaptations for osmoregulation (water balance)
• ↓ Water Loss– Conservation– Utilization (↑Efficiency)– ↑ Storage capacity– ↕ Solute/waste excretion
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LE 44-5Water
balance in a kangaroo rat(2 mL/day)
Waterbalance ina human
(2,500 mL/day)
Watergain
Waterloss
Derived frommetabolism (1.8 mL)
Ingestedin food (0.2 mL)
Derived frommetabolism (250 mL)
Ingestedin food (750 mL)
Ingestedin liquid (1,500 mL)
Evaporation (900 mL)
Feces (100 mL)Urine(1,500 mL)
Evaporation (1.46 mL)
Feces (0.09 mL)Urine(0.45 mL)
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Adaptations for osmoregulation (water balance)
• ↓ Water Loss– Conservation– Utilization (↑Efficiency)– ↑ Storage capacity– ↕ Solute/waste excretion
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LE 44-8
Nitrogenous bases
Nucleic acids
Amino acids
Proteins
—NH2
Amino groups
Most aquatic animals, including most bony fishes
Mammals, most amphibians, sharks, some bony fishes
Many reptiles (including birds), insects, land snails
Ammonia Urea Uric acid
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Waste management varies under different circumstances:
• Habitat– Terrestrial vs. aquatic turtles
• Reproductive strategy– Mammals: maternal transport of waste
– Amphibians: diffuse Ammonia out of egg (lacking shell)
– Birds/Reptiles: store as relatively less toxic uric acid
• Diet– ↑ Animal tissue => ↑ N-Wastes
• Metabolic requirement– ↑ metabolism => ↑ N-Wastes
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Adaptations for osmoregulation (water balance)
• ↓ Water Loss– Conservation– Utilization (↑Efficiency)– ↑ Storage capacity– ↕ Solute/waste excretion
• ↓Metabolic Requirements
• Unique physiologic structures– Renal structure– Salt Glands
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Reduce Metabolic Requirements– Reduce metabolic rate
• Slow heart, blood flow• Reduces O2 consumption• Reduces body temp
– Reduce activity• Seek shelter, such as a burrow,
shade, deeper water– e.g. Fennec, Leatherback
• Enter torpor (or estivation, in summer) – resting state
– e.g. Tarigrade, Mulgara, Long-necked Turtles
© C
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Hydrated tardigrade Dehydrated tardigrade
100 µm
100 µm
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Diffusion Osmosis• Solutes move from
greater solute concentration to lower conc.
• Diffusion of water through a selectively permeable membrane
Basic concept review:
3:2
3:1
Surface area to volume (SA:V)
d = 1
d = 2
Chptr 40: Animal Form & Function, pp. 820-821
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Dromedary or Arabian Camel(Camelus dromedarius)
Adaptations to ↓ Heat Loss• Anatomy
– Hump (Fat = H20 Storage)– Lips (chewing tough vegetation)– Double eyelashes
• Physiology– Increase body temp to match
ambient temp– Body temp. range: 34 - 42°C (8°C
range)
• Behavior– Huddling– Tracking sun
Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Mammalia Order Artiodactyla Family Camelidae
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LE 44-6
Control group(Unclipped fur)
Experimental group(Clipped fur)
Wat
er l
ost
per
day
(L/1
00 k
g b
od
y m
ass) 4
3
2
1
0
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Fennec Fox (Fennecus zerda [=Volpes zerda])
Sahara Desert• Anatomy
– Small body size– Large ears– Furred foot pads
• Behavior– Burrowing (↑ Humidity)– Nocturnal
• Physiology (↓Water Loss)– Reduced heart rate– Reduced metabolic rate
Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Mammalia Order Carnivora Suborder Caniformia Family Canidae
Banholzer, U. 1976. Water balance, metabolism, and heart rate in the Fennec. Naturwissenschaften 63 (4): 202-203.
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85 - 95 F
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Mulgara(Dasycercus cristicauda)
• Occurs in arid, sandy regions of Australia
• Related to marsupials• Example of convergent
evolution with rodents– Small size, long tail– Fossorial (burrowing)– Nocturnal
*Nocon, W. 1999. "Dasycercus cristicauda" (On-line), Animal Diversity Web. Accessed May 24, 2008 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Dasycercus_cristicauda.html.
Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Mammalia Infraclass Marsupialia Order Dasyuromorphia Suborder Dasyuridae Family Dasyurinae
–Torpor bouts 3 to 12 hr thus reduce metabolism to <12% of normal rate**
**Geiser, F and P. Masters. 1994. Torpor in relation to reproduction in the mulgara, Dasycercus cristicauda (Dasyuridae: Marsupialia) J. THERM. BIOL. 19 (1) pp. 33-40.
Bannertail kangaroo rat(Dipodomys spectabilis)
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LE 44-18c
Roadrunner(Geococcyx californianus)
Desert iguana(Dipsosaurus dorsalis)
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Marine Environment
• Ionic gradient set up: organism less salty than environment, salts want to enter body, water to leave (dehydration)
• Most marine invertebrates are osmoconformers• Most marine vertebrates and some invertebrates
are osmoregulators
• Hypotonic – less salty than environment• Hypertonic - saltier than environment
“Water, water everywhere, nor any drop to drink”- Coleridge
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Marine Invertebrates• Most inverts are osmo –
isotonic with environment (e.g. sponges)
• Some have specialized protonephridia composed of ciliated flame cells to transport solutes and waste products for elimination
Polyclad Flatworm
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Filtration
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Metanephridia: most annelids
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Malpighian tubules: insects
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Freshwater vs. Marine FishGain of water andsalt ions from foodand seawater
Osmotic water lossthrough gills and body surface
Excretion ofsalt ionsfrom gills
Excretion of salt ions and small amountsof water in scantyurine from kidneys
Excretelarge amounts ofDilute urine
Osmotic water gainthrough gills and body surface
salt ionsby gills
water and someions in food
Marine bony fishes are hypoosmotic to sea waterThey lose water by osmosis and gain salt by diffusion and from foodThey balance water loss by drinking seawater
Freshwater animals are hyperosmotic to their environmentThey lose salts by diffusion and maintain water balance by excreting large amounts of dilute urineSalts lost by diffusion are replaced by foods and uptake across the gills
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Green Sea Turtle(Chelonia mydas)
• The primary osmo-regulatory mechanism in sea turtles is the salt gland
• The surface area: volume ratio is different for age classes: a 50g immature has greater surface area, and larger relative salt glands (0.3% of body size) than a 50 kg subadult (0.05 –0.1%)– i.e., osmotic challenge varies by age
Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Reptilia Order Testudines Family Cheloniidae
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Leatherback Sea Turtle
(Dermochelys coriacea)
• Salt glands secrete monovalent ions (Na+), which is the main constituent of seawater, while renal system processes bivalent ions (Mg++)
• Sea turtles, marine reptiles & marine birds: super-saline secretions from salt glands– Lacrymal (turtles) – eye secretions– Nasal (lizards)– Post-orbital (birds)– Sublingual or premaxillary (snakes)– Lingual (crocodiles)
Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Reptilia Order Testudines Family Dermocheliidae
Prange, H.D. 1985. Osmoregulation: water and salt balance in sea turtles Copeia 1985 (3): 771-776.Hudson, D. M. and P. L. Lutz 1986. Salt Gland Function in the Leatherback Sea Turtle, Dermochelys coriacea Copeia, 1986 (1):247-249
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Salt glands in marine birds
Nostrilwith saltsecretions
Nasal salt gland
• Salt glands of marine birds remove excess sodium chloride from the blood• Use transport epithelia, which are specialized cells that regulate solute movement arranged in complex tubular networks
Pink-footed Shearwater (P. Hodum)Puffinus cretapus
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Vein
Capillary
Secretorytubule
Transportepithelium
Directionof saltmovement
Centralduct
Artery
Bloodflow
Lumen ofsecretory tubule
NaCl
Secretory cellof transportepithelium
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LE 44-13
RenalmedullaRenalcortex
Section of kidney from a ratKidney structure
Ureter
Kidney
Glomerulus
Bowman’s capsule
Proximal tubule
Peritubular capillaries
Afferentarteriolefrom renalartery
Distaltubule
Collectingduct
SEM
20 µm
Filtrate and blood flow
Vasarecta
Descendinglimb
Ascendinglimb
LoopofHenle
Renalmedulla
Nephron
Renalcortex
Collectingduct
Ureter
Urinary bladder
Urethra
Structure of Kidney
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LE 44-14
Filtrate
H2O
Salts (NaCl and others)
HCO3–
H+
Urea
Glucose; amino acids
Some drugs
Key
Active transport
Passive transportINNERMEDULLA
OUTERMEDULLA
NaCl
H2O
CORTEX
Descending limbof loop ofHenle
Proximal tubule
NaCl Nutrients
HCO3–
H+
K+
NH3
H2O
Distal tubule
NaCl HCO3–
H+K+
H2O
Thick segmentof ascendinglimb
NaCl
NaCl
Thin segmentof ascendinglimb
Collectingduct
Urea
H2O
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Kidney: Nephron
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California Sea Lion (Zalophus californianus)
• Derive water from food – fish, squid
• All marine mammals have reniculate kidneys
• which means that instead of having two single bean-shaped kidneys, each kidney is instead made up of grapelike clusters of smaller, independent kidney units, or renicles, as shown
Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Mammalia Order Carnivora Suborder Pinnipedia Family Otariidae
Cross-section
Marine Wildlife Veterinary Care & Research Center
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ADH: Anti-diuretic Hormone
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Mono Lake, CA (HN)
Hypersaline Environments
Often very simple food web & trophic level structure– Hypersaline lakes: – e.g. Mono Lake, Great Salt Lake
• Lower trophic level, low diversity: Brine shrimp (Artemia spp.)
• Higher trophic level, great diversity: shorebirds, gulls & grebes
Great Salt Lake, Utah (photo: NASA)
American Avocet
http://ut.water.usgs.gov/shrimp/index.html "Brine Shrimp and Ecology of Great Salt Lake", United States Geological Survey
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Avocets feeding in hypersaline Mono Lake, Lee County, CA 2007 © H. Nevins
Hypersaline Environments
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Hypersaline Environments
– High level of endemism– Hypersaline lagoons: – e.g. Laysan Is., NW Hawaiian
Islands• Brine flies (Ephydra spp.)• Laysan Duck (Anas laysanensis)
Laysan Is., Hawaii (photo: USFWS)
Laysan Ducks (photo: USFWS)
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California Gull, Mono Lake, CA 2007 © H. Nevins
READY FOR a QUIZ ???
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Quiz:
• Name three taxa which occur in freshwater-scarce environments
• Give a key physiological or behavioral adaptation for each to reduce water loss
• How would you expect the structure of the loop of Henle to differ among a tropical forest and a desert rodent?
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Answers:• Name three species which occur in freshwater-scarce
environments – Camelus, Artemia, Zalophus, others…
• Give a key physiological or behavioral adaptation for each to reduce water loss– Camelus: hump - water storage, orient to sun, fur– Mulgara: fossorial, torpor– Zalophus: reticulate liver
• How would you expect the structure of the Loop of Henle to differ among a tropical forest and a desert rodent?– Shorter in tropics, longer in desert to increase water absorption
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Questions?
Avocets feeding in hypersaline Mono Lake, Lee County, CA 2007 © H. Nevins