Osmotic and Ionic Regulation

The  ammonotelism, ureotelism and uricotelism are the adaptations of the animals for the removal of toxic nitrogenous wastes and thereby maintain homeostasis. Animals regulate the concentration of water and salts in their body fluids in accordance with their external environment. The process of maintenance of osmotic concentration of the body fluids is called osmoregulation. Osmoregulation and excretion are intimately related as the ultimate aim of these processes is to maintain homeostasis. These processes are performed by the same set of organs. Kidney is the major organ of osmoregulation in vertebrates. Gills, integument, salt glands and rectal glands assist kidneys in this endeavour.

The osmoregulatory organs of invertebrates are nephridia, antenna glands and malpighian tubules. The cuticle of insects also performs an excellent osmoregulatory function in both aquatic and terrestrial insects. In this unit you shall study about the osmotic environments, osmotic exchanges between animal and the environment, the mechanisms used by various animals to cope up with environmental osmotic extremes and also about role of hormones in osmotic and ionic regulation.