31st Lecture
Fri 03 April 2009
Housekeeping, Wed 01 April 2009
Readings
Today, Mon 30 Mar: Ch 26 (Ionic and Osmotic Balance )
Wed 01 April: Ch 27 (Osmoregulation)
LAB: Circulation; Lillywhite
Fri 03 April: Ch 27 (Osmoregulation)
Vertebrate Physiology
ECOL 437 (MCB/VetSci 437)
Univ. of Arizona, spring 2009
Kevin Bonine & Kevin Oh
Osmoregulation
Fri 13 Feb = Exam 1
Chapter 26 & 27
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Research Proposal Meetings
Lab discussion leaders: 01 Apr Lab discussion leaders: 08 Apr
1pm – Fred, Jarrett
1pm – xx
3pm – ??
3pm – xx
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Vertebrate
Galapagos Marine Ecology (ECOL 496O/596O)
Osmoregulation
Summer Session II: July 7-Aug 1, 2009
•Spend one month this summer in the Galapagos Islands, Ecuador!
•Visit seven of the most spectacular islands in the archipelago
•Do a service project with children at a local school and the Galapagos National Park
•Do a field ecology project and learn about Galapagos ecology and evolution
•Earn 3-6 units of graduate or undergraduate credit
For more information: http://www.eebweb.arizona.edu/courses/galapagos/
Katrina Mangin, mangin@email.arizona.edu, 520-626-5076
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4
Osmoregulation
Osmoregulation
-Ionic and
Osmotic Balance
-life arose in salty sea
-extracellular fluids ~ similar
-Kidney Function
-dist’n limited by temperature and osmotic pressure
(dehydration, ionic composition)
-terrestrial organisms (and their descendents) regulate
internal environment (homeostasis)
-salt and water regulation (waste excretion)
-kidneys, salt glands, gills
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1
Obligatory Osmotic Exchanges
Obligatory Osmotic Exchanges
1-Gradients
-Frog in freshwater
-Fish in ocean
4-Feeding, Metabolism, Excretion
-metabolic waste products
ammonia, urea, etc.
-metabolic water (desert!)
-ingestion of salts
-kidneys, salt glands, gills (more later)
2-Surface-to-Volume Ratio
-Small animals dehydrate or hydrate more rapidly
-Skin, and Respiratory surface
(higher metabolism with higher per/gram
respiratory surface)
5-Respiration
-internalize respiratory surface
-temporal countercurrent system
(dry and cool IN, becomes moist and warm; recover)
(countercurrent blood flow also)
-temperature regulation vs. water conservation
-ectotherm vs. endotherm (in deserts)
3-Integument Permeability
-Transcellular or Paracellular
-Aquaporins = water channel proteins
-Frogs vs. Lizards, Pelvic Patch etc.
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Osmoregulation
Osmoregulation
-Water Breathing
-Water Breathing
1. Fresh
Ambystoma tigrinum
Blood osmolarity 200-300 mosm/L
2. Salt (~1,000 mosm/L)
Most marine vertebrates hypo-osmotic
(e.g., teleost or bony fishes)
Water ~ 50 mosm/L
-
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hyperosmotic animals, danger of swelling, losing salts
get their water across skin
dilute urine
active uptake of salts across epithelium
fish gills, frog skin, etc.
-
danger of losing water, gaining too many salts
drink saltwater
excess salts actively secreted (gills, kidneys)
chloride cells for salt secretion
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10
Osmoregulation
-Air Breathing
Have to lose water to allow gas exchange
- Marine reptiles and marine birds can drink
seawater and secrete salts in high [ ]
Water Sources:
- SALT GLANDS
1 Free
- Mammals rely on kidney
2 Preformed
3 Metabolic
(14-8)
C6H12O6 + 6O2 ÅÆ 6CO2 + 6H20
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2
Hill et al. 2004, Fig 26.15
Mouse-to-Elephant Curve
(16-7)
Allometry
4g shrew eats 2g/day
elephant is 1 million x larger
Allometry
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14
Camel
K-rat
Lab rats
K-rat
Oryx
Hopping Mouse
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Osmoregulation
ORGANS THAT CONTRIBUTE TO OSMOREGULATION
IN VERTEBRATES
Group
Osmoregulatory Organs
Fish
Kidneys
Gills
Bladder
Intestine
Kidneys
Gills
Bladder
Skin
Intestine
Amphibians
Reptiles
Kidneys
Salt Glands
Intestine
Birds
Kidneys
Salt Glands
Intestines
Mammals
Kidneys
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-Air Breathing Desert Mammals
Behavior and Physiology
(Eckert 14-9)
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Kangaroo Rat
-Reduce Activity
-Remain in Cool Burrow
-Humid
-Water into dry seeds
-Highly concentrated urine
-Very dry feces (rectal absorption)
-Metabolic water
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3
Water
Phyllomedusa
Phyllomedusa sauvagi
Lose water:
evaporation
urine
feces
salt glands
eyes
Eleutherodactylus coqui
Pough et al., 2001
Alter behavior and physiology to minimize water loss
Water balance limits activity in time and space
Amphibs lose most water via evaporation
- cutaneous resistance
1 dried mucus
2 cocoon
3 wax
f
t
eo
Rol abita
h
o
r
c
mi
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Pough et al., 2001
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Water
Chuckwalla
Less
evap.
(lizards have more lipids in skin)
osmoregulation mechanisms
in gills, salt glands, and kidneys
Monkey Tree Frog
Anolis lizard
Alligator
Softshell Turtle
More
evap.
Bufo, Spadefoots, Rana
Pough et al., 2001
(free water surface)
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Salt Secretion:
Ionic & Osmotic
Homeostasis
recycle
extracellular
active
intracellular
Down electrochemical gradient
(Paracellular)
(Eckert 14-14)
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4
Salt Glands
Shark rectal glands to dispose of excess NaCl
Figure in Box 26.2
Hill et al. 2004
Chloride Cell
-blood hyperosmotic to seawater, but less salt
-more urea and TMAO (trimethylamine oxide)
-NaCl actively secreted
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Shark Rectal Salt Glands
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(Eckert 14-36)
Salt Glands
(Eckert 14-36)
Salt-secreting cells:
-Na/K-ATPase pump in basolateral
membrane
-generates gradient for Na+ by which
Na+/2Cl-/K+ cotransporter drives
up [Cl-] in cell
-Cl- across apical membrane
-Na+ follows paracellularly down
electrochemical gradient
(and H2O)
-apical membrane impermeable to urea
and TMAO
-therefore iso-osmotic secretion with
lots of NaCl
Nasal/orbital salt glands of birds and reptiles
-especially species in desert or marine environments.
Hypertonic NaCl secretions (2-3x plasma osmolarity)
Allows some birds to drink salt water and end up with
osmotically free water
… slightly different in birds and lizards
Æ
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Amblyrhynchus cristatus
Fish Gills
Chloride cells involved in osmoregulation
-(recall lab paper on smolting)
-lots of mitochondria to power ATPases
-mechanism similar in nasal glands (birds
and reptiles), and shark rectal gland
(Eckert 14-14)
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1
4
3
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Hill et al. 2004, Fig 26.7
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5
Freshwater fish:
The mechanism basically reversed to allow uptake of
salt from water against concentration gradient
(recall lab paper on smolting)
Sea ÅÆ Freshwater
Switch between getting rid of excess salt in
seawater and taking up salt in freshwater
Na/K-ATPase
to generate
Na gradient
proton pump to
create electrical
gradient
Growth hormone and cortisol for Æ sea
(more active chloride cells with more
Na/K-ATPase activity)
Prolactin for Æ freshwater
(Eckert 14-31)
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Gradients established and used…to move ions, water
Osmoregulatory Mechanisms
Apical surface (faces lumen and outside world)
Basal surface (faces body and extracellular fluid)
- Active movement of ions/salts requires ATP
- Movement of water follows movement of ions/salts
active
passive
(Eckert 14-12)
(14-11)
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Mammalian Kidney
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