The book deals with the neural integration of behavioral and physiological aspects of bodily homeostasis viewed from the standpoint of the lower brainstem, particularly the medulla oblongata. An historical framework is maintained. Functions covered include breathing, regulation of arterial pressure and blood flow to the tissues, arousal and nociception, and eating and metabolism. A concluding chapter, devoted to the human, includes an anatomical atlas of the human lower brainstem. Emphasis is placed on anatomically-established neural circuitry rather than on poorly characterized functional centers (e.g., vasomotor centers). Similarly, conventionally recognized neural systems, including the limbic system, the reticular formation and the autonomic nervous system, are shown to be unhelpful as explanatory concepts. The autonomic nervous system, for example, comprises afferent and efferent neurons which connect the brain with the various cardiovascular and visceral structures. It does not function in its own right. Patterns of autonomic discharge originate in the brain. The book stresses the role of the visceral information that reaches the brainstem via afferent components of the lower cranial nerves, including the vagus. Homeostatic functions involve changes in behavior as well as changes in internal physiological functions, an integration achieved by the nervous system functioning as a whole.