Chapter 1

1-1

Major Themes of Anatomy and Physiology

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Form and Function

•

Origins of Biomedical Science

•

Scientific Method 1-2

Major Themes of Anatomy and Physiology 2

• • • •

Human Origins and Adaptations Human Structure Human Function Language of Medicine 1-3

Anatomy - The Study of Form

• •

Observation of surface structure Cadaver dissection

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cutting and separation of organs to study their relationships

•

Comparative anatomy

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study of more than one species to analyze evolutionary trends 1-4

Anatomy - The Study of Form

• • •

Physical examination

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palpation, auscultation, percussion Gross anatomy

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visible with naked eye Histology

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examination of cells with microscope 1-5

Early Medical Illustrations

1-6

Physiology - The Study of Function

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Study of bodily functions

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using methods of experimental science

•

Comparative physiology

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study of different species

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Basis for the development of new drugs and medical procedures 1-7

Beginnings of Medicine

• •

Physicians in Mesopotamia and Egypt

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3000 years ago used herbal drugs, salts and physical therapy Greek physician Hippocrates

– –

established a code of ethics urged physicians to seek causes of disease 1-8

Beginnings of Medicine

• •

Aristotle

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called causes for disease physiologi complex structures are built from simpler parts Galen (physician to the Roman gladiators)

– –

saw science as a method of discovery did animal dissections since use of cadavers banned

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wrote book advising followers to trust their own observation 1-9

Birth of Modern Medicine

• • • •

Middle Ages

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little advancement

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medicine was taught as dogma with no new ideas Avicenna from Muslim world

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supported free inquiry over dogma

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wrote The Canon of Medicine, used in medical schools until 16th century Vesalius (1543)

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published accurate gross anatomy atlas Harvey (1628)

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realized blood flow out from heart and back in 1-10

Birth of Modern Medicine 2

• • •

Leeuwenhoek (1632-1723)

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invented a simple microscope (200x) to look at fabrics Hooke (1665) and Zeiss (1860)

– –

developed and improved compound microscope described plant cell walls in 1665 Schleiden and Schwann (1839)

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concluded that all organisms were composed of cells

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1 st tenet of cell theory 1-11

Early Compound Microscopes

The first cells seen were plant cell walls in a section of dried cork.

1-12

Living in a Revolution

• • •

Early pioneers were important

– –

established scientific way of thinking replaced superstition with natural laws Modern biomedical science

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technological enhancement

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diagnostic ability and life-support strategies Genetic Revolution

• •

human genome is finished gene therapy is being used to treat disease 1-13

Scientific Method

• •

Bacon (1561-1626) and Descartes (1596-1650)

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new habits of scientific thought

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England and France

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academies of science --still exist today Science

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produces reliable, objective and testable information about nature 1-14

Inductive Method

• • •

Philosopher Francis Bacon

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observations, generalizations and predictions

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anatomy Proof in science

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reliable observations

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tested repeatedly

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not falsified by any credible observation In science, all truth is tentative

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“proof beyond a reasonable doubt” 1-15

Hypothetico-Deductive Method

• •

Physiological knowledge Test your hypothesis (answer) to a specific question

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Good hypothesis

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consistent with what is already known

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testable and falsifiable with evidence

•

Hypotheses are written as If-Then statements 1-16

Proper Experimental Design

• • •

Sample size

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sufficient to prevent chance event Control group and treatment group

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identical treatment except for the variable being tested Prevention of psychosomatic effects

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use of placebo in control group 1-17

Proper Experimental Design 2

• •

Experimenter bias

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prevented with double-blind study Statistical testing

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difference between control and test subjects was not random variation

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due to the variable being tested 1-18

Peer Review

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Critical evaluation by other experts in the field

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done prior to funding or publication

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done by using verification and repeatability of results

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Ensures honesty, objectivity and quality in science 1-19

Facts, Laws and Theories

• • •

Scientific fact

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information independently verified Law of nature

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description of the way matter and energy behave

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results from inductive reasoning and repeated observations

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written as verbal statements or mathematical formulae Theory

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summary of conclusions drawn from observable facts it provides explanations and predictions 1-20

Human Origins and Adaptations

• •

Charles Darwin (1809-1882)

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On the Origin of Species by Means of Natural

Selection (1859)

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The Descent of Man (1871) Theory of natural selection

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how species originate and change through time changed view of “our origin, our nature and our place in the universe”

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increases understanding of form and function 1-21

Evolution, Selection, and Adaptation

• •

Evolution

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change in genetic composition of population

•

development of bacterial resistance to antibiotics Adaptations

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individuals with hereditary advantages

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produce more offspring under given selection pressures (harsh climate, predators)

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inheritable characteristics

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genetic change in the population (evolution) 1-22

Animal Relations

• •

Closest relative = chimpanzee

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difference of only 1.6% in DNA structure

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chimpanzees and gorillas differ by 2.3% Study of evolutionary relationships

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chose animals for biomedical research (the animal model)

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rats and mice used extensively due to issues involved with using chimpanzees 1-23

Primate Adaptations

• •

Earliest primates

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squirrel-sized, arboreal, insect-eating mammals

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due to safety, food supply and lack of competition Adaptations for aboreal life style

– – –

mobile shoulders opposable thumbs manipulate small objects forward-facing eyes (stereoscopic vision)

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depth perception for leaping and catching prey

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color vision

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distinguish ripe fruit

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larger brains and good memory

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remember food sources 1-24

Walking Upright

• • •

African forest became grassland

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millions of years ago Bipedalism

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standing and walking on 2 legs

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spot predators, carry food or infants Adaptations for bipedalism

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skeletal and muscular modifications 1-25

Walking Upright

• • • •

Australopithecus

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gave rise Homo habilis (2.5mya)

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taller, larger brain volume, speech, tool-making

Homo habilis

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gave rise to Homo erectus (1.1mya)

Homo erectus

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gave rise to Homo sapiens (.6 to .2mya?) Diseases and imperfections from our evolutionary past 1-26

Primate Phylogeny

1-27

Hierarchy of complexity

• • • •

organism is composed of organ systems organ systems composed of organs organs composed of tissues tissues composed of cells 1-28

Hierarchy of Complexity

• • •

Cells contain organelles Organelles composed of molecules Molecules composed of atoms 1-29

Anatomical Variation

•

No 2 humans are exactly alike

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variable number of organs

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variation in organ locations (situs inversus, dextrocardia, situs perversus) 1-30

Characteristics of Life

• • • • • • • • •

Organization Cellular composition Excretion Metabolism and excretion Responsiveness and movement Homeostasis Development Reproduction Evolution 1-31

Physiological Variation

• •

Sex, age, diet, weight, physical activity Typical values

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reference man

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22 years old, 154 lbs, light physical activity

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consumes 2800 kcal/day

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reference woman

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same as man except 128 lbs and 2000 kcal/day 1-32

Homeostasis

•

Claude Bernard (1813-78)

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stable internal conditions regardless of external conditions

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Homeostasis

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Walter Cannon (1871-1945) coined the term

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fluctuates within limited range around a set point

•

Loss causes illness or death 1-33

Negative Feedback Loop

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Body senses a change and activates mechanisms to reverse it 1-34

Negative Feedback, Set Point

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Room temperature does not stay at set point of 68 degrees -- it only averages 68 degrees 1-35

Human Thermoregulation

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Brain senses change in blood temperature

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if overheating, vessels dilate in the skin and sweating begins

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if too cold, vasoconstriction in the skin and shivering begins 1-36

Control of Blood Pressure

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Circulatory stretch receptors

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detect a rise in BP

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Cardiac center in brainstem

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sends out nerve signals

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Heart slowed and BP lowered 1-37

Structure of Feedback Loop

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Receptor = senses change Integrator = control center that responds

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Effector = structures that restore homeostasis 1-38

Positive Feedback Loops

• •

Self-amplifying change

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leads to change in the same direction Normal way of producing rapid changes

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occurs with childbirth, blood clotting, protein digestion, and generation of nerve signals 1-39

Life-Threatening Fever

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Temperature > 108 degrees F

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increases metabolic rate

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body produces heat even faster

• •

Cycle continues to reinforce itself Becomes fatal at 113 degrees F 1-40

Anatomical Terminology

• • •

Medical terms from Greek and Latin roots Naming confusion during the Renaissance

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same structures with different names

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structures named after people (eponyms) Search for uniform international terminology

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1895 Nomina Anatomica (NA) rejected all eponyms

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each structure = unique Latin name

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Terminologia Anatomica was codified in 1998 1-41

Analyzing Medical Terms

• •

Terminology based on word elements

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lexicon (Appendix C) Scientific terms

– – – – –

one root (stem) with core meaning combining vowels join roots prefix modifies core meaning suffix modifies core meaning Acronyms

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first few letters of series of words 1-42

Useful Tables in Textbook

1-43

Review of Major Themes

• • • • •

Cell theory

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activity of cells determine structure and function Homeostasis

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maintaining stable internal conditions Evolution

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our body evolved by natural selection Hierarchy of structure

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levels of complexity Unity of form and function

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physiology is inseparable from anatomy 1-44

Medical Imaging

• •

Radiography (x rays)

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William Roentgen - 1885 penetrate soft tissues and darken photographic film

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dense tissue remains white Radiopaque substances

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injected or swallowed hollow structures

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blood vessels intestinal tract 1-45

Medical Imaging

• •

Computed Tomography (CT scan)

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low-intensity X rays and computer analysis

• •

slice type image increased sharpness Magnetic Resonance Imaging (MRI)

– – –

slice type image best for soft tissue Mechanics

• • • • •

magnetic field aligns atoms radio waves realign the atoms radio turned off atoms realign to the magnetic field energy given off depending on tissue type 1-46

Medical Imaging

•

Positron Emission Tomography (PET scan)

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assesses metabolic state

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mechanics

•

inject labeled glucose

– –

positrons and electrons collide gamma rays given off

•

analyzed by computer

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image glucose usage 1-47

Medical Imaging

•

Sonography

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mechanics

•

high-frequency sound waves echo back from internal organs

– – –

avoids harmful x rays obstetrics 2 nd most commonly used technique 1-48