Endocrine versus Neural Integration
A question that surely comes across your mind is, "what is the need for two types of integrative mechanisms, the neural and the endocrine"? Each of these systems has particular properties and functions and therefore confers specific adaptations to the animal. Previously you have learnt that the nervous system responds rapidly to the various stimuli. Thus, when a rapid action is called for, nervous system will be more effective. On the other hand, in functions controlled through endocrine system hormone concentration is built up gradually, and, only when the titres reach a threshold level, the function of the cell or tissue or organ is carried out. Necessarily hormone concentration is built up gradually, the specific function is carried out and then the hormone is metabolised and broken down slowly. As a result, the effect of the hormone is sustained and continued for a long duration. So when rapid responses are required, like the escaping from a predator, the animal resorts to neural mechanism; but when a slow but sustained effect is called for, for example, during the growth of the animal or the development of the oocyte, the hormonal mechanism takes over.