Understanding of modern physiology has gone through several changes and through several stages of evolution, from the standpoint of health and its workings. At first, there used to be a static view of the individual and of specific functions of a body’s constituent organs and tissues. Gradually, it was realized that there was an integrative control mechanism through the nervous system and psychic influences could not be regarded as functioning separately from the body. A study of endocrine secretions led to discoveries of newer processes of physiologic and metabolic conditions having integrative chemical control on the body and subsequently, new light was thrown onto the cellular structure and function. And now it is known that the whole human physiology is an integrated process of interdependent components. The peculiar characteristic of the human body is its capability to modify its internal structure and function to cope up and adapt to changes in the external environment. This capability naturally involves a continuous maintenance of the body structure by means of periodic repair of an organ’s wear and tear and provision of a continuous supply of energy for maintaining the optimal temperature and keeping the various interdependent systems running, so as to help the organism react appropriately to environmental changes within and without the body. The following three systems are integral to every organism, big or small: | Understanding of modern physiology has gone through several changes and through several stages of evolution, from the standpoint of health and its workings. At first, there used to be a static view of the individual and of specific functions of a body’s constituent organs and tissues. Gradually, it was realized that there was an integrative control mechanism through the nervous system and psychic influences could not be regarded as functioning separately from the body. A study of endocrine secretions led to discoveries of newer processes of physiologic and metabolic conditions having integrative chemical control on the body and subsequently, new light was thrown onto the cellular structure and function. And now it is known that the whole human physiology is an integrated process of interdependent components. The peculiar characteristic of the human body is its capability to modify its internal structure and function to cope up and adapt to changes in the external environment. This capability naturally involves a continuous maintenance of the body structure by means of periodic repair of an organ’s wear and tear and provision of a continuous supply of energy for maintaining the optimal temperature and keeping the various interdependent systems running, so as to help the organism react appropriately to environmental changes within and without the body. The following three systems are integral to every organism, big or small: |