This anthology of articles is designed to supplement standard texts for courses in human physiology, environmental physiology, anatomy and physiology, pathobiology, general biology, and environmental medicine. It focuses on the influences of the external environment on the body, the physiological responses to environmental challenges, and the ways in which these responses contribute to either health or disease. The articles are organized into six sections, each preceded by a general introduction. The first four sections deal with the physiological effects of and responses to the nutritional, chemical, physical, and psychosocial environments. Next is a section discussing the immune defenses of the body, including responses to the microbial environment, reactions to cancer cells, and the problems of organ transplantation. The concluding section deals with the physiology of aging and brings together information and concepts from the earlier sections. The epilogue discusses the present evolution of man. (MM)