The material covered on pages 704-710 will not be covered in lecture but will be tested upon. All of Chapter 40 should be read. Physiology is the study of how organisms work or the study of the functions of all parts and processes of living systems. Physiology includes studying how living organisms adjust to the adversities of their environments. In order to understand how a complex organism works, it is necessary to understand the hierarchy of the components of an animal.
Homeostasis is the ability of the organism to maintain a relatively stable internal environment.
Thus homeostasis and the regulation of the internal environment are central precepts of animal physiology. Homeostasis is a continuous process that involves monitoring and regulating multiple parameters and coordinating the responses in order to minimize the disturbance to the organism. Examples of factors that are homeostatically controlled are nutrients, salts, wastes, oxygen and carbon dioxide, volumes and pressures, body pH, and temperature. In a negative feedback loop, the response opposes or removes the signal to stabilize the physiological variable. For positive feedback loops, the response reinforces or amplifies the stimulus rather than decreasing it or removing it and may lead to a vicious cycle.