Transcript Chapter 1

Chapter 1
1-1
Major Themes of Anatomy and
Physiology
• Form and
Function
• Origins of
Biomedical
Science
• Scientific Method
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Major Themes of Anatomy
and Physiology 2
• Human Origins and
Adaptations
• Human Structure
• Human Function
• Language of
Medicine
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Anatomy - The Study of Form
• Observation of surface structure
• Cadaver dissection
– cutting and separation of organs to study
their relationships
• Comparative anatomy
– study of more than one species to analyze
evolutionary trends
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Anatomy - The Study of Form
• Physical examination
– palpation, auscultation, percussion
• Gross anatomy
– visible with naked eye
• Histology
– examination of cells with microscope
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Early Medical Illustrations
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Physiology - The Study of
Function
• Study of bodily functions
– using methods of experimental science
• Comparative physiology
– study of different species
• Basis for the development of new
drugs and medical procedures
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Beginnings of Medicine
• Physicians in Mesopotamia and Egypt
– 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
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Beginnings of Medicine
• Aristotle
– 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
– wrote book advising followers to trust their own
observation
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Birth of Modern Medicine
• Middle Ages
– little advancement
– medicine was taught as dogma with no new ideas
• Avicenna from Muslim world
– supported free inquiry over dogma
– wrote The Canon of Medicine, used in medical
schools until 16th century
• Vesalius (1543)
– published accurate gross anatomy atlas
• Harvey (1628)
– realized blood flow out from heart and back in
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Birth of Modern Medicine 2
• Leeuwenhoek (1632-1723)
– 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)
– concluded that all organisms were composed of
cells
– 1st tenet of cell theory
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Early Compound Microscopes
The first cells seen were plant cell walls in a section of dried
cork.
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Living in a Revolution
• Early pioneers were important
– established scientific way of thinking
– replaced superstition with natural laws
• Modern biomedical science
– technological enhancement
• diagnostic ability and life-support strategies
• Genetic Revolution
• human genome is finished
• gene therapy is being used to treat disease
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Scientific Method
• Bacon (1561-1626) and Descartes
(1596-1650)
– new habits of scientific thought
• England and France
– academies of science --still exist today
• Science
– produces reliable, objective and testable
information about nature
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Inductive Method
• Philosopher Francis Bacon
– observations, generalizations and predictions
– anatomy
• Proof in science
– reliable observations
– tested repeatedly
– not falsified by any credible observation
• In science, all truth is tentative
– “proof beyond a reasonable doubt”
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Hypothetico-Deductive Method
• Physiological knowledge
• Test your hypothesis (answer) to a
specific question
• Good hypothesis
– consistent with what is already known
– testable and falsifiable with evidence
• Hypotheses are written as If-Then
statements
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Proper Experimental Design
• Sample size
– sufficient to prevent chance event
• Control group and treatment group
– identical treatment except for the variable being
tested
• Prevention of psychosomatic effects
– use of placebo in control group
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Proper Experimental Design 2
• Experimenter bias
– prevented with double-blind study
• Statistical testing
– difference between control and test
subjects was not random variation
– due to the variable being tested
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Peer Review
• Critical evaluation by other
experts in the field
– done prior to funding or publication
– done by using verification and
repeatability of results
• Ensures honesty, objectivity and
quality in science
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Facts, Laws and Theories
• Scientific fact
– information independently verified
• Law of nature
– description of the way matter and energy behave
– results from inductive reasoning and repeated
observations
– written as verbal statements or mathematical formulae
• Theory
– summary of conclusions drawn from observable facts
– it provides explanations and predictions
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Human Origins and
Adaptations
• Charles Darwin (1809-1882)
– On the Origin of Species by Means of Natural
Selection (1859)
– The Descent of Man (1871)
• Theory of natural selection
– how species originate and change through
time
– changed view of “our origin, our nature and
our place in the universe”
– increases understanding of form and function
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Evolution, Selection, and
Adaptation
• Evolution
– change in genetic composition of population
• development of bacterial resistance to antibiotics
• Adaptations
– individuals with hereditary advantages
– produce more offspring under given selection
pressures (harsh climate, predators)
– inheritable characteristics
• genetic change in the population (evolution)
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Animal Relations
• Closest relative = chimpanzee
– difference of only 1.6% in DNA structure
– chimpanzees and gorillas differ by 2.3%
• Study of evolutionary relationships
– chose animals for biomedical research
(the animal model)
– rats and mice used extensively due to
issues involved with using chimpanzees
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Primate Adaptations
• Earliest primates
– squirrel-sized, arboreal, insect-eating mammals
• 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)
• depth perception for leaping and catching prey
– color vision
• distinguish ripe fruit
– larger brains and good memory
• remember food sources
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Walking Upright
• African forest became grassland
– millions of years ago
• Bipedalism
– standing and walking on 2 legs
– spot predators, carry food or infants
• Adaptations for bipedalism
– skeletal and muscular modifications
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Walking Upright
• Australopithecus
– gave rise Homo habilis (2.5mya)
• taller, larger brain volume, speech, tool-making
• Homo habilis
– gave rise to Homo erectus (1.1mya)
• Homo erectus
– gave rise to Homo sapiens (.6 to .2mya?)
• Diseases and imperfections from our
evolutionary past
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Primate Phylogeny
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Hierarchy of complexity
• organism is composed
of organ systems
• organ systems
composed of organs
• organs composed of
tissues
• tissues composed of
cells
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Hierarchy of Complexity
• Cells contain
organelles
• Organelles composed
of molecules
• Molecules composed
of atoms
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Anatomical Variation
• No 2 humans are exactly alike
– variable number of organs
– variation in organ locations (situs inversus,
dextrocardia, situs perversus)
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Characteristics of Life
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Organization
Cellular composition
Excretion
Metabolism and excretion
Responsiveness and movement
Homeostasis
Development
Reproduction
Evolution
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Physiological Variation
• Sex, age, diet, weight, physical activity
• Typical values
– reference man
• 22 years old, 154 lbs, light physical activity
• consumes 2800 kcal/day
– reference woman
• same as man except 128 lbs and 2000 kcal/day
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Homeostasis
• Claude Bernard (1813-78)
– stable internal conditions regardless of
external conditions
• Homeostasis
– Walter Cannon (1871-1945) coined the term
– fluctuates within limited range around a set
point
• Loss causes illness or death
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Negative Feedback Loop
• Body senses a change and activates
mechanisms to reverse it
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Negative Feedback, Set Point
• Room temperature does not stay at set point
of 68 degrees -- it only averages 68 degrees
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Human Thermoregulation
• Brain senses change in blood temperature
– if overheating, vessels dilate in the skin and sweating begins
– if too cold, vasoconstriction in the skin and shivering begins
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Control of Blood Pressure
• Circulatory stretch receptors
– detect a rise in BP
• Cardiac center in brainstem
– sends out nerve signals
• Heart slowed and BP lowered
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Structure of Feedback Loop
• Receptor = senses change
• Integrator = control center that
responds
• Effector = structures that restore
homeostasis
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Positive Feedback Loops
• Self-amplifying change
– leads to change in the same direction
• Normal way of producing rapid changes
– occurs with childbirth, blood clotting, protein digestion, and
generation of nerve signals
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Life-Threatening Fever
• Temperature > 108 degrees F
– increases metabolic rate
– body produces heat even faster
• Cycle continues to reinforce itself
• Becomes fatal at 113 degrees F
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Anatomical Terminology
• Medical terms from Greek and Latin roots
• Naming confusion during the Renaissance
– same structures with different names
– structures named after people (eponyms)
• Search for uniform international terminology
– 1895 Nomina Anatomica (NA) rejected all eponyms
• each structure = unique Latin name
– Terminologia Anatomica was codified in 1998
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Analyzing Medical Terms
• Terminology based on word elements
– lexicon (Appendix C)
• Scientific terms
– one root (stem) with core meaning
– combining vowels join roots
– prefix modifies core meaning
– suffix modifies core meaning
– Acronyms
• first few letters of series of words
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Useful Tables in Textbook
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Review of Major Themes
• Cell theory
– activity of cells determine structure and function
• Homeostasis
– maintaining stable internal conditions
• Evolution
– our body evolved by natural selection
• Hierarchy of structure
– levels of complexity
• Unity of form and function
– physiology is inseparable from anatomy
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Medical Imaging
• Radiography (x rays)
– William Roentgen - 1885
– penetrate soft tissues and
darken photographic film
– dense tissue remains white
• Radiopaque substances
– injected or swallowed
– hollow structures
– blood vessels
– intestinal tract
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Medical Imaging
• Computed Tomography (CT scan)
– low-intensity X rays and computer analysis
• slice type image
• increased sharpness
• Magnetic Resonance Imaging (MRI)
– slice type image
– best for soft tissue
– Mechanics
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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
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Medical Imaging
• Positron Emission Tomography
(PET scan)
– assesses metabolic state
– mechanics
• inject labeled glucose
– positrons and electrons collide
– gamma rays given off
• analyzed by computer
– image glucose usage
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Medical Imaging
• Sonography
– mechanics
• high-frequency sound
waves echo back
from internal organs
– avoids harmful x rays
– obstetrics
– 2nd most commonly
used technique
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