This textbook, written in an easy to understand language and presented in a systematic format, enables the students to understand the principles and mechanisms of normal body functions so that they can appreciate how these mechanisms alter in illness. Clinical applications have been included in the text so that the students can understand why a patient has certain problem and thus the biological rationale for rendering appropriate medical and nursing care. In this edition new facts and concepts have been added and some parts of the text have been rewritten to update subject matter. All the illustrations have been modified, improved and redrawn to match the contemporary style of graphics seen in recent publications. The questions at the end of each chapter have been formulated to encourage students to relate to and apply the information required as their learning progresses. The book is more than sufficient for diploma in nursing and fully meets the requirements of BSc (Nursing) students. It will prove highly useful for the students of different diploma/degree courses in the field of allied health sciences.