(b) : Homoeostasis is the regulation by an organism of the chemical composition of its body fluids and other aspects of its internal environment so that physiological processes can proceed at optimum rates. It involves monitoring changes in the external and internal environment by means of receptors and adjusting the composition of the body fluids accordingly; excretion and osmoregulation are important in this process. Example of homeostatic regulation are the maintenance of the acid-base balance and body temperature.