Plasma and blood cells. Composition of plasma: electrolytes, organic molecules. Coelomic fluid differ in composition from that of circulatory fluids. Proteins in plasma and vertebrates and cephalopod mollusks have high plasma protein concentrations. Proteins is very important in osmotic pressure. Osmotic pressure due to proteins in called as colloid osmotic pressure.
in vertebrate animals, the circulating blogg fluid, is kept within a closed circulating system, whereas hemolymph is circulating fluid of animals with open circulator system, for example insect.
the coelomic fluid of some invertebrates also has a circulatorry role instead of blood. the function of blood, respiratory pigments in blood, transport of nutrients, circulate hormones, blood clotting immnune responses. Phagocytosis of dead cellls and foreing materials. Important pH buffer system, constituents of blood can confer antifreeze properties. Heat exchange.
In animals having open circulatory system, the blood volume is only a fraction of the extracellular fluid volume but blood volume is only a fraction of the extracellullar volume for animals with a closed circulatory system.