Osmoregulation = keeping water and salt balanced in the body Question 1: why is this important...
-
Upload
emily-ramsey -
Category
Documents
-
view
218 -
download
0
Transcript of Osmoregulation = keeping water and salt balanced in the body Question 1: why is this important...
Osmoregulation = keeping water and salt balanced in the body
• Question 1: why is this important – Come up with three reasons
• Question 2: What water and salt problems do the following organisms face?– Freshwater fish– Marine fish– Marine birds– Marine mammals
• Question 3: How might each group solve those problems?
Definitions• Solute• Solvent• Osmosis• Osmotic Pressure• Osmolarity• Hyperosmotic• Hypoosmotic• Osmoconformer• Osmoregulator
Solutes are dissolved particles in solution (any type)
•Osmotic pressure: the pressure of water to enter, given the solute concentration•--depends on the number of solutes/unit volume (rather than chemical nature of solutes)
isosmotic
•Osmotic pressure: the pressure of water to enter, given the solute concentration
(osmotic pressure is equal)
hypersmotic(higher osmotic pressure)
hyposmotic(lower osmotic pressure)
•Osmotic pressure: the pressure of water to enter, given the solute concentration
Water always moves from an area of low osmotic pressure to an area of high osmotic pressure
Hyposmotic (lower osmotic pressure)
Hyperosmotic (higher osmotic pressure)
osmotic pressure: the pressure of water to enter, given the solute concentration
Osmosis: movement of water from anArea with lower osmotic pressure to Higher osmotic pressure
Osmolarity= concentration of solutes in a solution
Osmolarity vs. Molarity:
150 mMol sucrose= 150 mOsm sucrose
150 mMol NaCl = 300 mOsm NaCl
Osmotic pressures are generally described in osmolar units:
Definitions• Solute:• Solvent:• Osmosis:• Osmotic Pressure:• Osmolarity:• Hyperosmotic:• Hypoosmotic:• Osmoconformer:• Osmoregulator:
Dissolved particles in a solution
movement of water from an area with lower osmotic pressure to higher osmotic pressure the pressure of water to enter,
given the solute concentration
Concentration of solutes in a solution
Higher osmotic pressure
Lower osmotic pressure
What the particles are dissolved in
Body fluid isoosmotic with envir.
Body fluid osmolarity regulated in opposition to environment
Freshwater teleosts: Osmoregulators
Problems?
• water gain• salt loss
Solutions?
• move salt into blood
• Lots of dilute urine
* The gills have specialized cells:
CHLORIDE CELLS: they result in the active uptake of ions across the gills
Hyperosmotic to environment
Main osmoregulatory
organ = skin
Problems?• Gaining water
Solutions?
• Losing salt
• dilute urine• pump salt into body
Amphibians: osmoregulatorsHyperosmotic to environment
…but no gills, so no chloride cells…
• Active transport of Na+ into animal
2 K+
3 Na+
ATP
Active transport of salts via skin:
Cl-Cl-
Cl-
• Cl- follows passively (electric gradient)
Marine teleosts:Osmoregulators(hyposmotic to environment)
Problems?• water loss
Solutions?
How?• excrete salt …
• salt gain
• produce little urine (isosmotic to plasma)
• gain water (food, drink)
Chloride Cells in the gills!Actively pump ions OUT
Marine reptiles and birds…Osmoregulators
Blood is hyposmotic to seawater
Can’t concentrate urine Can concentrate urine (a *little* bit!)
How do they get rid of huge salt load?
Marine reptiles and birds…
seawater3% salt
Salt glands!
Nasal fluid5 % salt
urine0.3% salt
Salt glands
• salt is excreted from the gland to outside the body• more concentrated than sea water!
• mechanism is same in marine reptiles-but salt gland is in different
places
Na+ mOsm
seawater 470
sea snake 620
sea turtle 690
Marine Iguana 1000-1400
gull 600-900
cormorant 500-600
petrel 900-1100
Cortex
OuterMedulla
InnerMedulla
Loop of Henle
mammalian nephron:
Na+Na+
Na+Na+
Na+Na+
• Na+ is pumped out of the filtrate
•Results in osmotic gradient in the kidney ECF
•Why does this matter?
300
600
900
300 mOsm
600
900
1200 mOsm 1200
Cortex
OuterMedulla
InnerMedulla
Loop of HenleAs filtrate passes through the collecting duct, it loses water to the ECF
H2O
H2O
H2O
H2O
300
600
900
300
600
900
1200mOsm
1200mOsm
How concentrated can the filtrate become in this organism?
~150
As concentrated as the ECF
Final urine is hyperosmotic
to plasma
• up to 4X in regular terrestrial mammals• up to 6X in marine mammals• up to 30X in desert mammals!
Marine MammalsLive in seawater…but no chloride cells, no salt glands…?
1. Long loop of henle in the kidney--concentrated urine--less water lost with waste
2. Diet--carnivores, eating mostly
vertebrates--vertebrates have lower osmolarity
3. Absence of sweat glands
Several Adaptations:
Osmoregulation = aquatic animals• Question 1: why is this important
– Low solute concentration: cells shrink– High solute concentration: cells burst– Cells need proper ion balance to function
• Muscle, nerve cells; Na+/K+ pump
• Question 2: Problems?• Question 3: solutions?
– Problem: solution– Freshwater fish
• Water gain: produce lots of dilute urine• Salt loss: pump salt in through chloride cells in gills
– Marine fish• Osmoconformers: no regulation• ionoconformers: increase plasma solutes—Urea• Osmoregulators
– Lose water: drink lots of sea water, produce little urine– Gain salt: Chloride Cells in gills
– Marine birds• Gain salt: excrete salt in salt glands
– Marine mammals• Gain salt: excrete hi solute urine
TERRESTRIAL VERTEBRATES
Water Gain:
1. Food/water intake
2. Metabolic water
Water Loss:
1. Excretiona) Fecalb) Urinary
2. Evaporative Water Lossa) Cutaneousb) Respiratory
3. Reproduction
In humans:
+ 2.2 L/day
+ 0.3 L/day - 1.6 L/day
- 0.9 L/day
Total Water gain and loss: 2.2 + 0.3 = 1.6 + 0.9
• Water soluble• Very toxic• Excreted w/lots of water
• Not water soluble• Low toxicity• Excreted w/little water
• Water soluble• Low toxicity• Excreted w/less water
Nitrogenous Wastes affect Water Balance
Proteins Nucleic acids
Nitrogenous waste products
UREAAMMONIA URIC ACID
Excretion
• ammonia
• urea
• uric acid
Teleost fish
chondrichthyes
Birds and reptiles
mammals
Amphibians reptiles
% of urinary nitrogen
Species Habitat Ammonia Urea Uric Acid
Red-eared slider Freshwater 79 17 4
Forest hinge-back tortoise
Moist Terrestrial 6 61 4
Mediterranean spur-thighed tortoise
Dry terrestrial 4 22 52
Texas tortoise Desert 4 3 93
Tortoises and Turtles:
Teleost fish Amphibians
Amphibians
reptiles
Mammals:• most drink, eat foods high in water •very concentrated urine
BUT, what about desert mammals?
How do Kangaroo Rats Cope?
• don’t pant• few sweat glands• LONG loop of henle•Human urine= 1200 mOsm•Kangaroo rat = 5500 mOsm
• eat dry food *• don’t drink! • don’t tolerate dehydration!C6H12O6 + 6O2 6 CO2 + 6H2O
Metabolic water:
How?
1 g glucose 0.6 g water
100g barley35 g
Water gains: Water losses:
54 mL: oxidation water6 mL: absorbed water
16.1 mL: urine, feces43.9 mL: evaporation
60 mL water 60 mL water
=
=
Urine = 9x higher osmolarity than sea water!!