Presentation on theme: "Ionic and Osmotic Balance. Ion & Water Balance Kidneys are main organs of ion & water balance Gills, skin, digestive mucosa all help with ion and water."— Presentation transcript:
ECF of most marine invertebrates is similar from seawater. ECF of most marine vertebrates is different from seawater. ECF of most marine vertebrates is similar to mammals.
ICF of most animals is low in Na +, Cl - but high in K +, phosphates and proteins.
Osmoregulatory mechanisms Frog in fresh water (hypo osmotic environment) not only must eliminate excess water but also retain ions that tend to leak though the skin. Since animals live in a wide range of environments many different osmoregulatory mechanisms have evolved.
Water Sources Aquatic environment Diet Metabolism
Regulatory Volume Decrease RVD K+ channels; Cl- channels (separate or as cotransporters) & these exit cell Na+/Ca2+ exchanger followed by Ca2+ ATPase to export calcium Na+/K+ ATPase pump Water follows
Osmotic and Ionic Differences Epithelia surrounding the body maintains both osmotic and ionic differences between the ECF and the external environment. Aquaporins are pores in epithelium for water passage Solutes move by transcellular and paracellular transport
Integument (epithelium plus underlying tissue). Permeability varies among animals. Insects: waxy impermeable cuticle. Amphibians skins: mucus, permeable. Water and ions move by diffusion. Loss of ions compensated by active transport. Fish gills: active transport of ions. Reptiles, birds and mammals: relatively impermeable keratinized skins. Perspiration can lead to substantial water loss.
Gills Transports ions in or out of water depending on salinity of water
Digestive mucosa Solutes move across digestive mucosa Water moves across digestive mucosa
Salt Glands Birds and reptiles Excretes Na+ and Cl- Functions as countercurrent multiplier systems