8/16/2019 Urogenital Tables

http://slidepdf.com/reader/full/urogenital-tables 1/1

Environment

Primary osmotic prob Sol’n

Example taxa

Freshwater

• Hypoosmotic envi

• Excess H2O

uptake

• Must excrete

excess H2O &conserve salts

• Waste excreted as ammonia

• Use excess H2O as solvent

• ctively transport solutes !or

retention

"W teleosts# a$uatic &semia$uativeamp%ibians

Salt

water

• Hyperosmotic

envi

• Excessive H2O

loss

• Excessive uptake

o! salts

• Must retain H2O#

eliminate salts

• soosmoticity

• 'ose (lomerulus )dec* H2O

loss+

• Hyperosmotic rel to envi

• ,etain urea

•

nc H2O uptake• ,etain (lomerulus to excrete

H2O

• Salt excretion (lands-

• ,ectal (land

• Salt (lands on (ills

• Ha(.s%

• Marine teleosts

• Elasmobranc%s )&

Latimeria+

• Elasmobranc%s

•  /eleosts

Terrestrial

• 0ry envi

• 'imited H2O & salts

• Must retain bot%

• secondary returnto H2O

• ,eintroduces

above a$uaticconcerns

• 1 excreted in all !orms

• 3alance costs vs bene.ts

• 4ariable amon( taxa

• 4ariable in li!e %istories

• ,educe (lomerulus

• Solute recovery

•'oop o! Henle or e$uivalent

• Salt (lands )elimination+

• 1onavian reptiles#

anurans

• 3irds & mammals

• Marine taxa

Form  o! 1itro(en

Energycost

Toxicity Solubility H2O,e$uirements

Ammonia

'east costly Hi(%lytoxic

Hi(%ly soluble 5reatest

Ureantermediate

Minimal 6uite soluble ntermediate

Uricacid

Minimal none Sli(%tly solublePpts 78 pHc%an(e

'east