Third Edition - Masaryk University

1 Third EditionPhysics in Biology and MedicineComplementary Science SeriesACADEMIC PRESS2008 To be publishedPhysics in the Arts (Full Edition ) Gilbert Willy Haeberli2003 2007 Physics in Biology and Medicine, Third EditionPaul DavidovitsCrystallography Made Crystal Clear, Third EditionGale RhodesFusionGarry M. McCracken Peter StottIntroduction to Quantum MechanicsSy M. BlinderFundamentals of Quantum Chemistry, Second EditionJames E. House2000 2002 Introduction to RelativityJohn B. KogutEarth Magnetism: A Guided Tour through Magnetic FieldsWallace H. CampbellThe Physical Basis of Chemistry, Second EditionWarren S. EditionPhysics in Biologyand MedicinePaul DavidovitsAMSTERDAM BOSTON HEIDELBERG LONDONNEW YORK OXFORD PARIS SAN DIEGOSAN FRANCISCO SYDNEY TOKYOA cademic Press is an imprint of ElsevierACADEMIC PRESSA cademic Press is an imprint of Elsevier30 Corporate Drive, Suite 400, Burlington, MA 01803, USA525 B Street, Suite 1900, San Diego, California 92101-4495, USA84 Theobald s Road, London WC1X 8RR, UKThis book is printed on acid-free 2008, Elsevier Inc.

2 All rights part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage andretrieval system, without permission in writing from the may be sought directly from Elsevier s Science & Technology RightsDepartment in Oxford, UK: phone: (+44) 1865 843830, fax: (+44) 1865 853333,E-mail: You may also complete your request onlinevia the Elsevier homepage ( ), by selecting Support & Contact then Copyright and Permission and then Obtaining Permissions. Library of Congress Cataloging-in-Publication DataDavidovits, in biology and medicine / Paul Davidovits. 3rd cm. (Complementary science series)Includes bibliographical references and : 978-0-12-369411-9 (pbk. : alk. paper) 1. Biophysics. 2. Medical physics. I. dc222007021167 British Library Cataloguing-in-Publication DataA catalogue record for this book is available from the British LibraryISBN: 978-0-12-369411-9 For information on all Academic Press publicationsvisit our web site at in the United States of America07080910 987654321 ContentsPrefacexiiiAbbreviationsxvii1 Static and Considerations for the Human of the Human Body under the Action of anExternal Tip-Toe on One Dynamic Aspects of at an at the Hip Fin of a Translational of Gravity on the Vertical High of a Broad Broad Jump (Long Jump).

3 Through Consumed in Physical Angular on a Curved Runner on a Curved of Walking and Expended in Perspectives on Walking And Elasticity and Strength of Stretch and Fracture: Energy Due to a Fall: Impulsive Force : Inflating Collision Protection from Great and Insect Wing Required for Energy of Wings in of and Pressure in a s Required to Remain of Locomotion on Contraction of The Motion of s and Poiseuille s of the of Blood of Blood in the and Blood Power Produced by the Measurement of Blood 114viiiContents9 Heat and Kinetic and Theory of of of of Molecules by through Respiratory and and Contact 13310 First Law of Second Law of Difference between Heat and Other Forms Thermodynamics of Living Information and the Second 14411 Heat and Energy Requirements of Energy from Regulation of Body Control of Skin Radiative Heating by

4 The Resistance to Heat and 15912 Waves and Properties of Some Properties of and Hearing and the of the and and Bats and Sounds Produced by Acoustic Clinical Uses of Ultrasonic 17813 The Nervous Potentials in the as an Electric of the Action Analysis of the Axon Potentials in Electricity in Electricity in the Electric 19814 Electrical Electrical Technology in Biological Diagnostic Physiological Effects of Control Sensory 21315 Nature of Structure of the Eye and the and Depth of Lens System of the Reduced Resolving Power of the Threshold of Vision and the Nervous Defects in Lens for Lens for Presbyopia and Extension of Confocal Fiber 23716 Atomic The Quantum Electron X-ray Computerized 25517 Nuclear The Magnetic Resonance Magnetic with Magnetic Resonance Imaging(fMRI).

5 Radiation Food Preservation by Isotopic Laws of Physics and 271 Appendix A: Basic Concepts in Mechanics272 Appendix B: Review of Electricity287 Appendix C: Review of Optics293 Bibliography302 Answers to Numerical Exercises310 Index314 Companion Web Site InformationInstructor support materials forPhysics in Biology and Medicine, Third Edition , can be found PrefaceUntil the mid 1800s it was not clear to what extent the laws of physics andchemistry, which were formulated from the observed behavior of inanimatematter, could be applied to living matter. It was certainly evident that on thelarge scale the laws were applicable. Animals are clearly subject to the samelaws of motion as inanimate objects. The question of applicability arose ona more basic level. Living organisms are very complex. Even a virus, whichis one of the simplest biological organisms, consists of millions of interactingatoms.

6 A cell, which is the basic building block of tissue, contains on the aver-age 1014atoms. Living organisms exhibit properties not found in inanimateobjects. They grow, reproduce, and decay. These phenomena are so differ-ent from the predictable properties of inanimate matter that many scientists inthe early 19th century believed that different laws governed the structure andorganization molecules in living matter. Even the physical origin of organicmolecules was in question. These molecules tend to be larger and more com-plex than molecules obtained from inorganic sources. It was thought that thelarge molecules found in living matter could be produced only by living organ-isms through a vital force that could not be explained by the existing laws ofphysics. This concept was disproved in 1828 when Friedrich W ohler synthe-sized an organic substance, urea, from inorganic chemicals. Soon thereaftermany other organic molecules were synthesized without the intervention ofbiological organisms.

7 Today most scientists believe that there is no specialvital force residing in organic substances. Living organisms are governed bythe laws of physics on all of the biological research during the past hundred years has beendirected toward understanding living systems in terms of basic physical effort has yielded some significant successes. The atomic structure ofmany complex biological molecules has now been determined, and the role ofthese molecules within living systems has been described. It is now possible toexplain the functioning of cells and many of their interactions with each the work is far from complete. Even when the structure of a complexmolecule is known, it is not possible at present to predict its function from itsatomic structure. The mechanisms of cell nourishment, growth, reproduction,and communication are still understood only qualitatively. Many of the basicquestions in biology remain unanswered.

8 However, biological research hasso far not revealed any areas where physical laws do not apply. The amazingproperties of life seem to be achieved by the enormously complex organizationin living aim of this book is to relate some of the concepts in physics to livingsystems. In general, the text follows topics found in basic college physicstexts. The discussion is organized into the following areas: solid mechanics,fluid mechanics, thermodynamics, sound, electricity, optics, and atomic andnuclear chapter contains a brief review of the background physics, but mostof the text is devoted to the applications of physics to biology and previous knowledge of biology is assumed. The biological systems tobe discussed are described in as much detail as is necessary for the physicalanalysis. Whenever possible, the analysis is quantitative, requiring only basicalgebra and biological systems can be analyzed quantitatively.

9 A few exampleswill illustrate the approach. Under the topic of mechanics we calculate theforces exerted by muscles. We examine the maximum impact a body cansustain without injury. We calculate the height to which a person can jump,and we discuss the effect of an animal s size on the speed at which it can our study of fluids we examine quantitatively the circulation of blood inthe body. The theory of fluids allows us also to calculate the role of diffusionin the functioning of cells and the effect of surface tension on the growth ofplants in soil. Using the principles of electricity, we analyze quantitativelythe conduction of impulses along the nervous system. Each section containsproblems that explore and expand some of the are, of course, severe limits on the quantitative application of physicsto biological systems. These limitations are of the advances in the life sciences have been greatly aided by theapplication of the techniques of physics and engineering to the study of livingsystems.

10 Some of these techniques are examined in the appropriate sectionsof the new Edition has been updated and includes a discussion of informa-tion theory and descriptions of CT scan, endoscopy, MRI and fMRI imaging,techniques that were not available at the writing of the earlier word about units. Most physics and chemistry textbooks now use theMKS International System of units (SI). In practice, however, a variety ofunits continues to be in use. For example, in the SI system, pressure isexpressed in units of pascal (kg/m2). Both in common use and in the sci-entific literature one often finds pressure also expressed in units of dynes/cm2,Torr (mm Hg), psi, and atm. In this book I have used mostly SI units. How-ever, other units have also been used when common usage so dictated. Inthose cases conversion factors have been provided either within the text or ina compilation at the end of Appendix A.