Biophysics For Dummies E-Book

Ken Vos

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 651

Veröffentlichungsjahr: 2013

Beschreibung

The fun, easy way to get up to speed on biophysics concepts, principles, and practices One of the most diverse of modern scientific disciplines, biophysics applies methods and technologies from physics to the study of biological systems and phenomena, from the human nervous system to soil erosion to global warming. What are the best options for satisfying the world's growing energy demands? How can we feed the world's growing population? How can we contain, or reverse, global warming? How can we vouchsafe a plentiful supply of potable water for future generations? These are among the critical questions to which biophysicists work to provide answers. * Biophysics courses are increasingly taken by students of biology, physics, chemistry, biochemistry, physiology, statistics, bioengineering, neuroscience, computer science, pharmacology, agriculture,and many more * Provides a friendly, unintimidating overview of the material covered in a typical college-level biophysics course * A one-stop reference, course supplement and exam preparation tool for university students currently enrolled in an introductory biophysics courses * An indispensable resource for those studying the natural sciences, biological sciences, and physics, as well as math, statistics,computer science, pharmacology and many other disciplines * The current job market for people well versed in biophysics is very strong, and biophysics is currently listed as one of the fast-growing occupations in the North America

Leseprobe

Biophysics For Dummies®

Published by: John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030-5774, www.wiley.com

Copyright © 2013 by John Wiley & Sons, Inc., Hoboken, New Jersey

Published simultaneously in Canada

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ISBN: 978-1-118-51350-7 (pbk); ISBN: 978-1-118-51352-1 (ebk); ISBN: 978-1-118-51353-8 (ebk); ISBN: 978-1-118-51354-5 (ebk)

Manufactured in the United States of America

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Biophysics For Dummies®

Visit www.dummies.com/cheatsheet/biophysics to view this book's cheat sheet.

Table of Contents

Introduction

About This Book

Foolish Assumptions

Icons Used in This Book

Beyond This Book

Where to Go from Here

Part I: Getting Started with Biophysics

Chapter 1: Welcoming You to the World of Biophysics

Getting the Lowdown on What Biophysics Really Is

Grasping the Mechanics of Biomechanics

Surveying the rules

Focusing on statics

Going the dynamic route

Moving around with kinematics

Eyeing the Physics of Fluids

Understanding fluid’s mechanics and cohesive forces

Tackling fluid dynamics

Moving through membranes and porous materials

Comprehending Waves and Sound

Disturbing the material

Knowing how animals and instruments make sound waves

Hearing sound waves

Applying sound waves

Forcing Biophysics onto the World

Binding with the electromagnetic force

Getting a hold on radiation and how it battles cancer

Working with radiation

Using biophysics in medicine

Chapter 2: Interrogating Biophysics: The Five Ws and One H

Figuring Out What Biophysics Is

Locating Biophysics: The Where

Understanding Why Biophysics Is Important

Determining When Biophysics Is Relevant

Finding Out Who Are Biophysicists

Answering the Hows of Biophysics

Chapter 3: Speaking Physics: The Basics for All Areas of Biophysics

Stretching Out in All Physical Dimensions with Units

Grasping Scalars, Vectors, and Their Properties

Defining Physical Quantities

Plotting the position

Rotating to an angular position

Timing the change: Velocity

Scoping out speed

Focusing on angular velocity

Examining the direction of angular ­variables

Measuring acceleration

Describing momentum

Interacting with others: Force

Spreading force over an area: Pressure

Going ’round and ’round: Axis of rotation

Distributing mass: Moment of inertia

Quantifying motion: Angular momentum

Tackling torque

Working with work

Perusing power

Eyeing energy

Part II: Calling the Mechanics to Fix Your Bio — Biomechanics

Chapter 4: Bullying Biomechanics with the Laws of Physics

Recognizing That the Force Is Always with You: Newton’s Laws

Moving with inertia — Newton’s first law of motion

Stopping requires force — Newton’s second law of motion

Interacting takes two — forces and Newton’s third law of motion

Meeting Conservative Forces — No Tea Party Folks Here

Hooking into Hooke’s Law

Getting heavy with the effect of gravity

Recognizing the Nonconservative Forces: No Bleeding Hearts Here

Walking in the park — static friction

Hurting in the joints when moving — kinetic friction

Identifying other nonconservative forces

Thinking Green — Conservation Is Good; So Is Energy, Work, and Power

Conserving momentum

Moving energy and work

Working with energy and power

Colliding objects

Chapter 5: Sitting with Couch Potatoes –– Static Equilibrium

Understanding Static Translational Equilibrium

Solving static translational equilibrium problems

Drawing free-body diagrams

Finding forces with static translational equilibrium

Turning to Static Rotational Equilibrium

Solving rotational equilibriums

Doing static rotational free-body diagrams

Bending to the will of static rotational equilibrium

Breaking Rigid Bodies with Static Equilibrium

Applying static translational equilibrium multiple times — break a leg

Applying static rotational and static translational equilibrium — the iron cross

Chapter 6: Building the Mechanics of the Human Body and Animals

Getting Down with Gravity

Shifting to the center of mass

Staying stable and balanced

Feeling the Effects of Acceleration

Noticing the physiological effects of acceleration

Gaining a hold of effective weight — blackouts and redouts

Perceiving angular momentum and balance

Floating in space and the effects of weightlessness

Rising of the Machines — The Bio-Terminator

Marching to the mechanical advantage

Perusing the machines within biomechanics

Working with your body

Responding to Biological System’s Forces

Grasping elasticity, stress, and strain

Bending, buckling, and compressing

Shearing and twisting

Defining Scaling: No Scales Required

Growing cows and trees

Scaling in the body

Chapter 7: Making The World Go Round with Physics –– Dynamics

Reducing Motion to a Straight Line

Riding my bike

Racing the horses

Simplifying the dynamics of multiple objects in contact

Discovering Forces and Torques Involved with Circular Motion

Racing on a circular track — forces and acceleration

Accelerating around the corner — torques and forces

Chapter 8: Looking at Where Moving Objects Go –– Kinematics

Grasping One-Dimensional Motion

Analyzing sprinters’ run — the 100-meter dash

Dunking the basketball — people and animals’ jumping abilities

Skydiving and non-uniform acceleration

Spinning In Circles

Moving With Noncircular Two-Dimensional Motion

Serving in tennis — projectile motion

Pouncing on prey — combining jumping and projectile motion

Part III: Making Your Blood Boil — The Physics of Fluids

Chapter 9: Understanding the Mechanics of Fluids and Cohesive Forces

Pushing On Fluids — Pressure and Density

Squeezing atoms together — density and pressure

Weighing air and fluids — Pascal’s principle

Gauging blood pressure

Examining Why Things Float

Floating in fluid — Archimedes’ principle and the buoyant force

Measuring the density of the human body

Solving Conservation Laws

Grasping the continuity equation

Understanding Bernoulli’s equation

Applying Bernoulli’s equation to static fluids

Sticking Together — Cohesive Forces

Fighting surface tension

Making contact with capillarity and contact angles

Blocking fluids with Laplace’s law

Sneaking oxygen into the body

Looking into negative pressure in water columns

Chapter 10: Going with the Fluid Flow — Fluid Dynamics

Ignoring Friction Nonviscous Fluids

Conserving energy with Bernoulli’s equation

Flowing air — wind, birds, planes, and baseball

Regulating temperature in warm-blooded animals — conservation of heat energy

Applying the heat formulas to biophysics

Fighting the Drag — Viscous Flow

Stressing out with viscous fluids

Classifying viscous fluids — Newtonian and non-Newtonian fluids

Flowing slowly at the edge — laminar flow and Poiseuille’s law

Flowing of the blood and flow resistance

Pumping of the heart — making the blood move

Chapter 11: Breaking through to the Other Side — Transport, Membranes, and Porous Material

Examining the Ins and Outs of Diffusion

Defining the diffusion coefficient

Flowing through materials — Fick’s law

Restricting what passes through the ­barrier — osmosis and osmosis pressure

Understanding Human Metabolism

Eating — balancing your energy

Searching for efficiency of food energy

Eliminating Product from the Body

Keeping doses low — classical kinetics

Indulging too much — Michaelis-Menten kinetics

Part IV: Playing the Music Too Loud — Sound and Waves

Chapter 12: Examining the Physics of Waves and Sound

Comprehending Harmonic Motion

Explaining harmonic motion in action

Weighing a virus: Applying Hooke’s law and harmonic motion

Swinging in a swing: Applying gravity and harmonic motion

Comprehending Waves and Their Properties

Dealing with all types of waves

Grasping physical properties of waves

Going the math route with waves

Adding linear superposition and interference

Seeing the Effect of Boundaries on the Wave

Traveling from a medium into a denser medium

Traveling from a medium into a less dense medium

Going to extremes: Open and closed boundaries

Resonating with resonance

Chapter 13: Grasping How Animals and Instruments Produce Sound Waves

Knowing the Nature of Sound and the Speed of Sound

Vibrating the air and pressure waves

Speeding ticket for sound

Exploring the physical properties of sound

Resonating with Vibrations and Resonance

Resonating with a clarinet

Vibrating air in a flute

Combining Cords: The Human Voice and Musical Instruments

Tying down the strings and cords

Checking body resonance in an acoustic guitar

Collapsing cavities

Chapter 14: Detecting Sound Waves with the Ear

Understanding Hearing and the Ear

Outer ear

Middle ear

Inner ear

Realizing How Sensitive the Human Ear Is — the Power of Sound Waves

Taking a closer look at ear power

Tuning into a sound wave

Grasping the eardrum and limit range

Grasping How Amazing Hearing Is

Interacting complex waves

Beating beats and tuning a guitar

Chapter 15: Listening to Sound — Doppler Effect, Echolocation, and Imaging

Forecasting with the Doppler Effect

Moving on the receiver’s end

Moving on the source’s end

Moving sources and receiver

Considering the special case — light

Finding Your Way in the Dark — Echolocation

Echolocating with constant frequency sound waves and the Doppler Effect

Triangulating with frequency modulated sound — echolocation

Understanding the Limited Range of Echolocation

Seeing the Unseen: Ultrasound Imaging

Part V: Interacting Subatomic Particles’ Influence on Biological Organisms

Chapter 16: Charging Matter: The Laws of Physics for Electricity, Magnetism, and Electromagnetism

Forcing Matter in Biological Systems to Interact

Describing matter by their properties: The Lorentz force

Sticking balloons on the wall: Coulomb’s law and static charge

Producing electric fields

Producing magnetic fields and the Biot-Savart law

Changing electric fields create magnet fields: Maxwell-Ampere law

Creating electric fields: Faraday’s law

Resisting AC/DC — the resistance of the human body and other resistors

Storing energy with charge: Capacitors

Connecting Electric Circuits

Conserving energy: Ohm’s law and the power dissipation of devices

Drawing road maps for electrons: Circuits and circuit diagrams

Conserving energy and charge within a circuit: Kirchhoff’s laws

Chapter 17: Tapping into the Physics of Radiation

Understanding What Nuclear Physics and Radioactivity Are

Explaining radioactivity

Decaying of elements – the physical half-life

Identifying the three types of isotopes

Debunking Misconceptions about Electromagnetic Radiation

Understanding non-ionizing radiation

Comprehending ionizing radiation

Seeing How Radioactivity Interacts with Biological Systems

Finding a date in archaeology — call Carbon-14

Eliminating radioactive material within the body — biological half-life

Determining how radioactive humans are

Chapter 18: Fighting the Big C –– But Not All Radiation Is Bad

Investigating Radiation within Biological Systems

Interacting radiation with matter

Hurting cells with radiation — mechanisms of cell damage

Exposing the Body to Radiation

Estimating the effects from radiation

Measuring the unhealthy effects of radiation

Glowing walls — all matter is radioactively decaying

Looking closer at lung cancer

Chapter 19: Seeing Good Biophysics in the Medical Field

Identifying Radiation at Work in Medicine

Arming dentists and doctors with X-ray machines

Producing radionuclides and radiopharmaceuticals — nuclear medicine

Focusing Your X-Ray Vision — Computer Tomography (CT) Scans

Zapping the body — how CT works

Looking inside the body — what CT is used for

Staying away — who should avoid CT scans

Posing For Pictures — Positron Emission Tomography (PET)

Setting up the PET — how does it work

Picturing the body — what is PET used for

Part VI: The Part of Tens

Chapter 20: Ten (or So) Tips to Help You Master Your Biophysics Course

Drawing Diagrams and Figures

Obeying the Rules

Creating Your Own Dictionary

Understanding the Concepts

Not Fearing the Mathematics

Applying the Knowledge in Your Field

Networking with Your Classmates

Surfing the Internet

Chatting with Biophysicists

Chapter 21: Ten Careers for People Studying Biophysics

Experimental Biophysicist in Academia

Theoretical Biophysicist in Academia

Biophysicists outside Academia

Nuclear Power Reactor Health Physicist

Governmental Health Physicist

Environmental Health Physicist

Medical Health Physicist

Radiation Therapy Medical Physicist

Diagnostic Imaging Medical Physicist

Nuclear Medicine Medical Physicist

About the Author

Cheat Sheet

Connect with Dummies

Introduction

Welcome to Biophysics For Dummies. Biophysics is a fascinating field of science that combines the study of the laws of physics with the study of systems involving living organisms (biology). The combination of these two fields makes biophysics interdisciplinary, which means biophysicists work side by side with people from many different backgrounds. Biophysics is a very diverse and interesting field; even if you spend your entire life studying biophysics, you can still discover new and interesting pieces of information.

About This Book

Biophysics For Dummies lays down the foundations for the fields of biophysics, including neurophysics, medical physics, health physics, and related fields that overlap with biophysics, presented in an easy-to-access manner. This reference book presents biophysics in plain English, so you can easily find what you’re looking for. When you’re reading, you don’t have to begin at the beginning. You can go directly to the chapter or section that interests you and start reading. Of course, I prefer that you read it from cover to cover, but then again, I am a bit biased. If you’re strapped for time and only want to read what you need to know, even when you’re reading the chapter or section of interest to you, you can skip the sidebars and the paragraphs marked with the Technical Stuff icon without losing any of the essential info.

This book is unique in that the majority of the material is at the introductory level, but the material presented is at an advanced enough level that you can use the book as a stepping stone in your biophysics studies. This book also lays out in a clear step-by-step procedure how to apply concepts in physics to problems in biophysics and the life sciences. The book introduces topics in the five fundamental areas of physics: mechanics, fluids, thermodynamics, electromagnetism, and nuclear physics.

You may notice while reading the book that I have done a few things that I hope make your reading and search of information easier:

I avoid using URLs. These URLs can change over time, so I have placed only the more important ones that probably won't change on the online Cheat Sheet. You can find all the important links in a single place for easy access with a single click at www.dummies.com/cheatsheet/biophysics.

I italicize all the variables used in mathematical formulas, so you can easily identify them. I also italicize words when I define them. Many words in biophysics have special meanings, and understanding the terminology is an important step toward comprehending the subject.

I use certain symbols differently than do some other biophysics books. The symbols are as follows:

• N for the torque instead of τ (tau), which is used in many introductory books. (Many engineering books use M.) Some more advanced physics books use N for torque and in addition, τ looks very similar to t (time), T (period), and T (half-life). I would have too many physical quantities using similar symbols.

• P(a) for absolute pressure, P(g) for gauge pressure, and P for power. I have too many sections where I use power and pressure at the same time, so I distinguish them this way.

• E represents energy and F represents force. I distinguish between the different energies and forces by using subscripts. Some books use T or K for the kinetic energy and some use U or V for the potential energy. I use EK and EP instead for kinetic energy and potential energy.

Foolish Assumptions

As I write this book, I assume you, my dear reader, fall into at least one of the following groups:

You’re in college and taking an introductory biophysics course.

You’re interested in studying biophysics or some related field where knowledge of biophysics is useful.

You’re involved with the sciences and want to expand your knowledge base in biophysics.

You have already taken algebra, geometry, and a science course in either biology, chemistry, or physics.

Icons Used in This Book

I use a few icons as markers in the margins. These markers are useful for helping you locate material or skip over material, depending on what you’re searching for. I use them to indicate what I think is important for you to notice. These icons can help you navigate through the material.

When I present helpful information that can make your life a bit easier when studying biophysics, I use this icon.

This icon highlights important pieces of information that I suggest you store away because you’ll probably use them on a regular basis.

This icon highlights common mistakes or errors that I see time after time from people who are taking a biophysics course.

This icon indicates in-depth examples. Try solving the problem and continue reading to see how to solve the problem.

This icon requires nonessential information, usually at least at a calculus background level. If you have a math phobia, then you may want to avoid reading these paragraphs. If you enjoy biophysics and mathematics, then I encourage you to read these paragraphs.

Beyond This Book

In addition to the material in Biophysics For Dummies, I also provide a free Cheat Sheet online at www.dummies.com/cheatsheet/biophysics. The Cheat Sheet adds a few extra tidbits that you will find interesting, such as solving biomechanical problems. You can also find other interesting bits of additional information online at www.dummies.com/extras/biophysics.

After reading the Cheat Sheet and online information, you may decide to pursue biophysics more in-depth, so I include URLs to the biophysical society, the association of medical physicists, and the health physics society. These links are a great starting point in search of answers to your biophysical questions.

Where to Go from Here

Science is about being curious and exploring, which is what attracted me to biophysics. As you read this book, feel free to jump around and start with the chapters and sections that interest you the most. If you need a particular section for your science course, such as kinematics or biomechanics, you can go straight there. You can also look in the index or the table of contents to find a topic that interests you. No matter what you decide to read, enjoy your adventure into the world of biophysics.

Part I

Getting Started with Biophysics

Go to www.dummies.com/cheatsheet/biophysics to discover some more informative Dummies content online about biophysics.

In this part . . .

Get a thorough overview of what biophysics is, including its diverse fields, such as biomechanics, fluids, waves and sound, the electromagnetic force, and medical physics, so you can fully appreciate how it affects your daily life.

Discover where you can find biophysics. You may be surprised to know who biophysicists are and where biophysics is used.

Tackle mathematics, most of which should be a review for you if you’ve already taken a chemistry, physics, or calculus class. Biophysics does use mathematics, so having a decent grasp of the basic formulas and equations is important when you study biophysics.

Comprehend some of the basics of biophysics, such as notation and terminology, that aren’t used in everyday life and clear up a few common myths.

Make the distinction between experimental and theoretical biophysics. Biophysics isn’t mathematics, but mathematics is a tool used by both experimental and theoretical biophysicists.

Chapter 1

Welcoming You to the World of Biophysics

In This Chapter

Mentioning mechanics

Flowing with fluids

Riding the waves

Identifying biophysics in the every day

Biophysics is the study of biology and all sciences connected to the biological sciences using the principles and laws of physics. It’s the ultimate interdisciplinary science combining biology, chemistry, and physics. If you love science, then biophysics is for you. The field touches on all aspects of all the natural sciences.

This chapter gives you the bird’s-eye view of biophysics and what you’ll find in this book. In this chapter, I explain the general features of biomechanics, the motion of fluids, waves and sounds, and electromagnetic force as well as radiation and radioactivity.

Getting the Lowdown on What Biophysics Really Is

No matter if you’re stuck taking a biophysics course to meet your science course requirements or you’re taking your first of many biophysics courses, you need to make sure you understand what you’re studying. Just break down the word biophysics.Bio means life and physics means nature, so biophysics is the study of living matter, its motion, and its interaction with the natural universe. Chapter 2 expands on the explanation of what biophysics is, and Chapter 3 covers some of the basic terminology used in biophysics.

The following clarifies what biophysics really means:

Biophysics uses techniques and methods from physics, mathematics, biology, and chemistry to study living organisms.

Biophysicists design experiments or do computational calculations in order to understand biological processes. A few examples of these biological processes are

• Photosynthesis

• The on-off switching of genes

• Memory and brain processes

• Muscle control

Biophysicists study how the senses work.

Biophysicists try to understand why things behave the way they do in sports and improve the performance of athletes.

Biophysicists study how molecules enter cells and how they interact.

Biophysicists study how cells move, divide, and respond to the environment.

As you can see, biophysics is all of this and everything that deals with living organisms. Biophysics plays an essential role in medicine, sports, engineering, physics, biology, biochemistry, and environmental science to mention a few areas. Whenever you’re considering something that involves a living organism and its interaction with its surroundings, you’re using biophysics.

Grasping the Mechanics of Biomechanics

Biomechanics is an important part of biophysics. Bio means life, and mechanics is the study of the interaction of a physical object with its surroundings. Therefore, biomechanics is the study of a living object’s interaction with its surroundings, which also includes the study of how living organisms move and the causes of this motion.

These sections explain a bit more about what biomechanics is. I discuss rules because biophysicists love rules, explain what happens when forces try to change an object’s motion, and look at the motion of an object.

Surveying the rules

Biomechanics has many rules because things don’t happen randomly or bychance. Things happen because of actions, and these rules tell you what the consequences of an action are. These rules are usually called whichcan’t be broken.