This text bridges the gap between introductory physics and its application to the life sciences. There are many topics treated in this wide-ranging book. The fourth edition is updated throughout to reflect new developments; the discussion of theory is more closely linked to experiment; a discussion of stochastic processes is added; the discussions of anatomy and biology are expanded. The text includes many problems to test the student's understanding, and chapters include useful bibliographies for further reading. Its minimal prerequisites and wide coverage make it ideal for self-study, as well as a useful reference for workers in medical and biological research.