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)

Water always moves from an area of low osmotic pressure to an area of high osmotic pressure

osmotic pressure:

Osmosis:

Freshwater teleosts: Osmoregulators

Problems?

Solutions?

Hyperosmotic to environment

• 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)

Cl-

Na+

Marine Strategies

Cartilaginous fish

Marine teleosts:Osmoregulators(hyposmotic to environment)

Problems?

Solutions?

How do they get rid of huge salt load?

Marine reptiles and birds…

seawater

Salt glands!

Nasal fluid urine

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

How do mammals make concentrated urine?

Each nephron has a loop of Henle:

nephron loopofHenle

Cortex

OuterMedulla

InnerMedulla

Loop of Henle

mammalian nephron:

Na+Na+

Na+Na+

Na+Na+

mOsm

Marine Mammals

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:

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

Forest hinge-back tortoise

Moist Terrestrial

Mediterranean spur-thighed tortoise

Dry terrestrial

Texas tortoise Desert

Tortoises and Turtles:

Teleost fish Amphibians

Amphibians

reptiles

Terrestrial summary• Water in:

– Food and drink– Metabolic water

• Water out:– excretion– Evaporative water loss

• Adaptations in the desert?– Extended loop of henle– Reduced evaporative water loss

• (gain in camel nose)– High dehydration tolerance