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- Control of solute balance and the gain and loss of water.
- - Animal cells cannot survive wide changes in water content
- a large gain will cause cell to swell and burst;
- a large loss will cause it to shrivel and die.
movement of water across a selectively permeable membrane
total solute concentration (i.e., moles of solute per liter of solvent)
Solutions are equal in osmolarity; no net osmosis occurs between solutions.
- A solution having a greater concentration of solutes;
- net osmosis occurs into the solution (i.e., water will move into a hyperosmotic solution)
A solution having a lesser concentration of solutes. Osmosis occurs out of this solution (i.e., water moves out of a hyposmotic solution).
Terrestrial animals live in a dehydrating environment and cannot survive desiccation.
- Humans die if 12% of their body water is lost.
-Osmoregulatory mechanisms in terrestrial animals include protective outer layers, drinking and eating moist foods, behavioral adaptations and excretory organ adaptations.
...some desert animals
a) Arthropods have waxy cuticles, land snails have shells, and vertebrates are covered by a multi-layer skin comprised of dead, keratinized cells.
b) Some desert animals are nocturnal. Being active at night reduces dehydration and some (e.g., kangaroo rat) produce large amounts of metabolic water.
c) Excretory organs of terrestrial animals are adapted to conserve water while eliminating wastes.
Transport Epithelia and Osmoregulation
Animals have different variations of __ to regulate the __.
- Usually a __ of cells, joined by __, facing the external environment.
- The __ of epithelium's plasma membrane determines the specific __functions.
- transport epithelia
- transport of salt.
- single sheet
- impermeable tight junctions
- molecular composition
Examples of osmoregulation
- gill epithelium
- epithelium of marine birds
- extra funciton
- Gill epithelium pumps salt out of marine fish and into freshwater fish.
- Epithelium in the nasal glands of marine birds pump out excess salts obtained from drinking seawater.
- May also function in excretion of nitrogenous wastes in some anim