An Introduction to MEDICAL SCIENCE

Transcription

1 An Introduction to MEDICAL SCIENCE

2 An Introduction to MEDICAL SCIENCE A Comprehensive Guide to Anatomy, Biochemistry and Physiology by Ned Durkin ~ MT~LIMITED International Medical Publishers

3 Dedication To my late father, my mother and all my other good teachers. Knowledge is like a garden: ifit is not cultivated, it cannot be harvested. -Guinean proverb Published by MTP Press Limited Falcon House, Cable Street Lancaster, England Copyright 1979 Ned Durkin No part of this book may be reproduced in any form without permission from the publishers, except for the quotation of brief passages for the purpose of review. British Library Cataloguing in Publication Data Durkin, Ned An introduction to medical science. 1. Human physiology I. Title 612 QP34.5 ISBN-13: e-isbn-13: DOl: /

4 Contents Preface vii 1. An Introduction to Anatomy, Biochemistry and Physiology 2. Units, Definitions and the General Organization and Systems of the Body The Cells and Tissues The Blood The Skeletal System The Joints or Articulations The Muscular System The Circulatory (Cardiovascular) System The Lymphatic System and Lymph The Respiratory System The Urinary System ph and Hydrogen Ion Regulation The Digestive System Metabolism and Nutrition The Endocrine System The Reproductive System The Nervous System The Eye and the Ear The Skin 257 Index. 265

5 Preface This is a book for beginners. I have tried to write a text that would be helpful to students of diverse backgrounds who are starting basic science studies in preparation for work in one of the many health fields. In some ways this is a conventional text. It clearly states, for instance, that most people have but one heart, two kidneys and 12 pairs of cranial nerves. In some ways it is different from other texts. First, it begins with the basic physics, chemistry and biology necessary for understanding anatomy, biochemistry and physiology. Secondly, it tries to stress the relevance of these sciences to health, disease and patient care. Medicine is the science and art concerned with the preservation and restoration of health and with the care or cure of the person with disease. Today, for everyone physician, there are more than nine other medical professionals, although the ratio varies from country to country. These "helping people" include nurses, therapists, technicians, pharmacists, medical assistants and even the caring family and friends of those who are ill. Unlike music and mathematics, medicine has never had any child prodigies. Professional excellence in a medical field has always been achieved slowly, by hours of study and work, and has been built on a rock -solid foundation of basic science. Students today begin their professional studies with varying amounts and quality of preparation. Too often the students' foundation of basic science is shaky, and for them the process of knowledge building is nearly impossible. Even bright, well-motivated students can have difficulty and almost drown in what seems to be a sea of unrelated and incomprehensible facts. You simply cannot understand how people breathe unless you know about some of the physics of gases. To learn how the kidneys function you must first know osmosis, as well as hypotonic and hypertonic solutions. Metabolic pathways can be memorized, but it is not easy to make much sense Of them unless you have a grasp of elementary chemistry. To deal with this problem of student preparation I have added, where appropriate, mini-reviews of basic science principles, and have attempted to define or explain unfamiliar or complex scientific terms as their use arises. The first Chapters, for example, contain material on the atom and elements, chemical classes, osmosis, the cell, scientific units and anatomical terms. Most people who study the basic health sciences do not intend to become professional scientists. Generally they want to learn how to provide a service for a patient or the community. In turn, most people who seek medical help do not voice their complaints in precise anatomical, biochemical or physiolq,gical terms. It would be an unusual patient who complains that something is wrong with his or her DNA synthesis, that his or her systolic blood pressure is too low, or that his or her blood sugar concentration is too high. Still, for students, the basic sciences are essential not only for knowing how the body functions in health, but also for understanding the signs and symptoms of disease, the how and why of laboratory tests and clinical procedures, and the logic of correct diagnosis and treatment 'of disease. Knowledge precedes care. As more and more people become involved in providing health care, the necessity increases for learning and sharing this vital knowledge. To conclude on a real note of hope and encouragement, I believe that students can - with perseverance - learn the material, see its beauty and worth, and enjoy doing it. Many persons have helped me with this book. I am grateful to Virginia Carlson, Stina Miller, Peres Owuor and Elaine Parthanais for their expert typing and other 'kindnesses. David Horrobin, DPhil, MRCP, Doris Arnold, RN, and Margaret Nishakawara, PhD, have read various chapters and made excellent suggestions. Gregory Nicolosi, PhD, and Joseph Foley, MD, also have helped generously. Dr Horrobin initiated the project and provided invaluable advice. I am most indebted to him. Mr D. G. T. Bloomer and his staff at MTP Press Limited are to be commended for their expertise and their patience. I would like also to thank all my students in the United States, the West Indies and East Africa for their encouragement and insights. And finally, thanks to my friends and my family, too, for their generous and loving assistance. All errors are exclusively my own. Teaching is a communal experience. A teacher can always tell from the puzzled looks and shaking heads that it is time to erase, to begin again. Writing is a solitary act. It lacks the interaction of the classroom, and the finished textbook does not come with an eraser. Because I cannot see my readers' reactions I would like to hear from them, to be told what is or isn't clear and useful, and what might be added to make this a better book. I shall endeavour to reply to all correspondence sent to me at the following address: Ned Durkin, PhD, MD PO Box Cleveland Heights, Ohio USA