Transcript Chapter 1

Chapter 1
Lecture Outline
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Major Themes of Anatomy and
Physiology
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• Form and Function
Organism
• Origins of
Biomedical Science
Organ system
Tissue
Organ
• Scientific Method
Cell
Macromolecule
Organelle
Figure 1.7
Atom
Molecule
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Major Themes of Anatomy
and Physiology 2
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• Human Origins
and Adaptations
Organism
• Human Structure
• Human Function
Organ system
Tissue
Organ
Cell
• Language of
Medicine
Figure 1.7
Macromolecule
Organelle
Atom
Molecule
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Anatomy - The Study of Form
• Examining structure of the Human Body
–
–
–
–
inspection
palpation
auscultation
percussion
• Cadaver dissection
– cutting and separation of tissues to reveal their
relationships
• Comparative anatomy
– study of more than one species in order to examine
structural similarities and differences, and analyze
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evolutionary trends
Anatomy - The Study of Form
• Exploratory Surgery
– open body and take a look inside
• Medical imaging
– viewing the inside of the body without surgery
– Radiology – branch of medicine concerned with imaging
• Gross Anatomy
– study of structures that can be seen with the naked eye
• Cytology
– study of structure and function of cells
• Histology (microscopic anatomy)
– examination of cells with microscope
• Ultrastructure
– the molecular detail seen in electron microscope
• Histopathology
– microscopic examination of tissues for signs of disease
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Physiology - The Study of
Function
• Subdisciplines
– neurophysiology (physiology of nervous system)
– endocrinology (physiology of hormones)
– pathophysiology (mechanisms of disease)
• Comparative Physiology
– limitations on human experimentation
– study of different species to learn about bodily function
• animal surgery
• animal drug tests
– basis for the development of new drugs and medical
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procedures
Greek and Roman Legacy
• Physicians in Mesopotamia and Egypt
– 3000 years ago used herbal drugs, salts and
physical therapy
• Hippocrates - Greek physician
– “father of medicine”
– established a code of ethics (Hippocratic Oath)
– urged physicians to seek natural causes of disease
rather than attributing them to acts of the gods and
demons
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Greek and Roman Legacy
• Aristotle
– one of the first philosophers to write about
anatomy and physiology
– believed that diseases had either supernatural
causes or physical causes
• called supernatural causes of disease theologi
• called natural causes for disease physiologi
• this gave rise to the terms: physician and physiology
– believed that complex structures are built from
simpler parts
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Greek and Roman Legacy
• Claudius Galen
– physician to the Roman gladiators
– did animal dissections since use of cadavers banned
in his time
– saw science as a method of discovery not just a body
of facts taken on faith
– wrote book advising followers to trust their own
observation more than the teaching of dogma of the
“ancient masters”
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Birth of Modern Medicine
• Christian culture of Europe in Middle Ages
– science severely repressed
– taught medicine primarily as dogmatic commentary on Galen
and Aristotle
– crude medical illustrations
• In Jewish and Muslim cultures free inquiry was less
inhibited
• Jewish physician Maimonides (Moses ben Maimon)
– wrote 10 influential medical texts
– was physician to Egyptian sultan, Saladin
• Avicenna (Ibn Sina) from Muslim world
– “the Galen of Islam”
– combined Galen and Aristotle findings with original discoveries
– wrote The Canon of Medicine, used in medical schools for 500
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years
Birth of Modern Medicine
th
around the 16 century
• Andreas Vesalius
– taught anatomy in Italy
– Catholic Church relaxed restrictions on dissection of cadavers and
permitting autopsies
– barbering and surgery were considered ‘kindred arts of the knife’
– performed his own dissections rather than the barber-surgeons
– published first atlas of anatomy, Di Humani Corporis Fabrica (On the
Structure of the Human Body) in 1543
• William Harvey
– early physiologist…contributions represent the birth of experimental
physiology
– remembered for early studies on blood circulation
– realized blood flows out from heart and back to it again
– published book De Motu Cordis (On the Motion of the Heart) in 1628
– Michael Servetus, along with Harvey, were the first Western
scientists to realize that blood must circulate continuously around the
body, from the heart to other organs, and back to the heart again 1-11
Early Medical Illustrations
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Art Resource
Figure 1.2
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© SPL/Photo Researchers, Inc.
Figure 1.3
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Birth of Modern Medicine
• Robert Hooke
– made many improvements to the compound microscope -2 lensesocular lens (eyepiece) and objective lens (near specimen)
• invented specimen stage, illuminator, coarse and fine focus controls
• his microscopes magnified only 30X
• first to see and named ‘cells’
– published first comprehensive book of microscopy (Micrographia) in
1665
• Antony van Leeuwenhoek
– invented a simple (single-lens) microscope with great magnification to
look at fabrics (200X)
– published his observations of blood, lake water, sperm, bacteria from
tooth scrapings and many other things
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Birth of Modern Medicine
• Carl Zeiss & Ernst Abbe
– greatly improved compound microscopes
– added condenser and superior optics
• eliminated blurry edges (spherical aberration) and rainbow-like distortions
(chromatic aberration)
• Matthias Schleiden and Theodor Schwann
– with improved microscopes, examination of a wide variety of
specimens followed
– concluded that “all organisms were composed of cells”
– first tenet of Cell Theory
• considered as the most important breakthrough in biomedical history
• all functions of the body are interpreted as effects of cellular activity
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Early Compound Microscopes
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Figure 1.4
(a)
(b)
a: Courtesy of the Armed Forces Institute of Pathology; b: © Corbis–Bettmann
The first cells seen were plant cell walls in a section of dried cork.
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Living in a Revolution
• Modern biomedical science
– technological enhancements
• advances in Medical Imaging have enhanced our
diagnostic ability and life-support strategies
• Genetic Revolution
• human genome is finished
• gene therapy is being used to treat disease
• Early pioneers were important
– established scientific way of thinking
– replaced superstition with natural laws
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Scientific Method
• Francis Bacon, in England, and
Rene Descartes, in France
– philosophers who invented new habits of scientific
thought
– sought systematic way of seeking similarities,
differences, and trends in nature and drawing useful
generalizations from observable facts
• Governments of England and France
– established academies of science -- still exist today
• Science and scientific methods
– set standards for truth
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Inductive Method
• Described by Francis Bacon
– making numerous observations until one becomes
confident in drawing generalizations and predictions from
them
– knowledge of anatomy obtained by this method
• Proof in science
– reliable observations
– tested and confirmed 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
• more physiological knowledge gained by this
method
• investigator asks a question
• formulates a hypothesis- an educated speculation or
possible answer to the question
– characteristics of a good hypothesis
• consistent with what is already known
• testable and possibly falsifiable with evidence
• Falsifiability – if we claim something is scientifically true,
we must be able to specify what evidence it would take to
prove it wrong
• Hypothesis - to suggest a method for answering
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questions - are written as ‘If-Then’ statements
Experimental Design
• Sample size
– number of subjects used in a study
– controls for chance events and individual variation
• Controls
– control group and treatment group
– comparison of treated and untreated individuals
• Psychosomatic Effects
– effects of the subject’s state of mind on his or her
physiology
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– use of placebo in control group
Proper Experimental Design
• Experimenter bias
– prevented with double-blind study
• Statistical testing
– provides statements of probability
– difference between control and test subjects
was not random variation
– results 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 that can be independently verified by a trained
person
• Law of nature
– generalization about the predictable way matter and
energy behave
• results from inductive reasoning and repeated observations
• written as verbal statements or mathematical formulae
• Theory
– an explanatory statement or set of statements derived from
facts, laws, and confirmed hypotheses
• summarizes what we know
• suggests direction for further study
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Human Origins & Adaptations
• Charles Darwin
– On the Origin of Species by Means of Natural
Selection (1859) – ‘book that shook the world’
– The Descent of Man (1871) – human evolution
• 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 human form and
function
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Evolution, Selection, and
Adaptation
• Evolution
– change in genetic composition of population of organisms
• development of bacterial resistance to antibiotics
• appearance of new strains of AIDS virus
• Natural Selection
– some individuals within a species have hereditary
advantage over their competitors
• better camouflage
• disease resistance
• ability to attract mates
– produce more offspring and advantage passed on
– Selection Pressures – natural forces that promote
the reproductive success of some individuals more
than others
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Evolution, Selection, and
Adaptation
• Adaptations – features of an organism’s
anatomy, physiology, or behavior that have evolved
in response to these selection pressures and
enable the organism to cope with the challenges of
its environment.
– Model – animal species selected for research on a
particular problem
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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
– help us chose animals for biomedical
research (the animal model)
– rats and mice used extensively due to issues
involved with using chimpanzees
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Vestiges of Human Evolution
• Vestigial Organs – remnants of organs that
apparently were better developed and more
functional in the ancestors of a species, and now
serve little or no purpose
– piloerector muscle
– auricularis muscles
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Life in the Trees
• Primates – order of mammals to which humans, monkeys, and apes
belong
• Earliest Primates
– squirrel-sized, arboreal, insect-eating African mammals
– moved to trees due to safety, food supply and lack of competition
• Adaptations for arboreal (treetop) life style
– mobile shoulders
– opposable thumbs made hands prehensile to grasp branches and
encircle them with the thumb and finger
– forward-facing eyes (stereoscopic vision)
• depth perception for leaping and catching prey
– color vision
• distinguish ripe fruit and young, less toxic foliage
– larger brains and good memory
• remember food sources and improved social organization
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Walking Upright
• African forest became grassland 4-5 million
years ago
– producing more predators and less protection
• Bipedalism - standing and walking on 2 legs
– helps spot predators, carry food or infants
• Adaptations for bipedalism
– skeletal and muscular modifications
– increased brain volume
– family life and social changes
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Walking Upright
• Australopithecus – oldest bipedal primate
• Homo genus (appeared 2.5 million years ago)
• taller, larger brain volume, probable speech, tool-making
• Homo erectus (appeared 1.8 million years ago)
– migrated from Africa to parts Asia
• Other Homo species discovered recently still
matter of considerable debate
• Homo sapiens originated in Africa 200,000
years ago
– sole surviving hominid species
• Evolutionary (darwinian) medicine traces
some of our diseases and imperfections to
our past
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Hierarchy of Complexity
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• Organism is composed of
organ systems
Organism
• Organ Systems composed of
organs
• Organs composed of tissues
• Tissues composed of cells
• Cells composed of organelles
• Organelles composed of
molecules
• Molecules composed of
atoms
Figure 1.7
Organ system
Tissue
Organ
Cell
Macromolecule
Organelle
Atom
Molecule
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Hierarchy of Complexity
• Organism – a single, complete individual
• Organ System – human body made of 11 organ systems
• Organ – structure composed of two or more tissue types that work together to carry
out a particular function
• Tissue – a mass of similar cells and cell products that form discrete region of an
organ and performs a specific function
• Cells – the smallest units of an organism that carry out all the basic functions of life
– Cytology – the study of cells and organelles
• Organelles – microscopic structures in a cell that carry out its individual functions
• Molecules – make up organelles and other cellular components
– macromolecules – proteins, carbohydrates, fats, DNA
• Atoms – the smallest particles with unique chemical identities
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Hierarchy of Complexity
• Reductionism – theory that a large, complex system
such as the human body can be understood by studying
its simpler components
– first espoused by Aristotle
– highly productive approach
– essential to scientific thinking
• Holism – there are ‘emergent properties’ of the whole
organism that cannot be predicted from the properties of
the separate parts
– humans are more than the sum of their parts
– complementary theory to reductionism
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Anatomical Variation
• No two humans are exactly alike
– 70% most common structure
– 30% anatomically variant
– variable number of organs
• missing muscles, extra vertebrae, renal arteries
– variation in organ locations (situs solitus, situs
inversus, dextrocardia, situs perversus)
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Normal
Pelvic kidney
Horseshoe kidney
Figure 1.8
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Normal
Variations in branches of the aorta
Characteristics of Life
• Organization
• Cellular composition
• Metabolism
– anabolism, catabolism and excretion
• Responsiveness and movement
– stimuli
• Homeostasis
• Development
– differentiation and growth
• Reproduction
• Evolution
– mutations
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Physiological Variation
• Sex, age, diet, weight, physical activity
• Typical physiological 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
• Overmedication of elderly
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Homeostasis
• Homeostasis – the body’s ability to detect change,
activate mechanisms that oppose it, and thereby maintain
relatively stable internal conditions
• Claude Bernard (1813-78)
– constant internal conditions regardless of external
conditions
• internal body temperature ranges from 97 to 99 degrees despite
variations in external temperature
• Walter Cannon (1871-1945)
– coined the term ‘Homeostasis’
– state of the body fluctuates (dynamic equilibrium) within
limited range around a set point
– Negative feedback keeps variable close to the set point
• Loss of homeostatic control causes illness
or death
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Negative Feedback Loop
• Body senses a change and activates mechanisms
to reverse it - dynamic equilibrium
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1
Room temperature
falls to 66°F (19°C)
C 10°
15°
20°
25°
F 50°
60°
70°
80°
6 Room cools down
2
C 10°
15°
20°
25°
F 50°
60°
70°
80°
Thermostat activates
furnace
5 Thermostat shuts
off furnace
4 Room temperature
rises to 70°F (21°C)
(a)
3 Heat output
Figure 1.9a
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Negative Feedback, Set Point
Room temperature (°F)
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(b)
75
Furnace turned
off at 70°F
70
Set point 68°F
65
Furnace turned
on at 66°F
60
Time
Figure 1.9b
• Room temperature does not stay at set point of
68 degrees -- it only averages 68 degrees
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Negative Feedback in Human
Thermoregulation
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Core body temperature
Sweating
37.5°C
(99.5°F)
Vasodilation
37.0°C
(98.6°F)
Set point
Vasoconstriction
36.5°C
(97.7°F)
Time
Figure 1.10
Shivering
• Brain senses change in blood temperature
– if to warm, vessels dilate (vasodilation) in the skin and sweating
begins (heat losing mechanisms)
– if too cold, vessels in the skin constrict (vasoconstriction)
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and shivering begins (heat gaining mechanism)
Negative Feedback Control of
Blood Pressure
• Sitting up in bed causes a drop in blood pressure
in the head and upper thorax
• Baroreceptors in the arteries near the heart alert
the cardiac center in the brainstem
• Cardiac center sends nerve signals that increase
the heart rate and return the blood pressure to
normal
• Failure of this to feedback loop may produce
dizziness in the elderly
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Control of Blood Pressure
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Person rises
from bed
Blood pressure rises
to normal; homeostasis
is restored
Cardiac center
accelerates heartbeat
Blood drains from
upper body, creating
homeostatic imbalance
Baroreceptors above
heart respond to drop
in blood pressure
Figure 1.11
Baroreceptors send signals
to cardiac center of brainstem
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3 Components of a Feedback
Loop
• Receptor - senses change in the body
• Integrating (Control) Center - control
center that processes the sensory
information, ‘makes a decision’, and
directs the response
• Effector – carries out the final corrective
action to restore homeostasis
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Positive Feedback Loops
• Self-amplifying cycle
– leads to greater change in the same direction
– feedback loop is repeated – change produces more change
• Normal way of producing rapid changes
– occurs with childbirth, blood clotting, protein digestion, fever, and
generation of nerve signals
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3 Brain stimulates
pituitary gland to
secrete oxytocin
4
Oxytocin stimulates uterine
2 Nerve impulses
contractions and pushes
from cervix
fetus toward cervix
Transmitted
to brain
1 Head of fetus
pushes against cervix
Figure 1.12
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Harmful Positive Feedback Loop
• Fever > 104 degrees F
– metabolic rate increases
– body produces heat even faster
– body temperature continues to rise
– further increasing metabolic rate
• Cycle continues to reinforce itself
• Becomes fatal at 113 degrees F
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Anatomical Terminology
• Standard International Anatomical Terminology
– Terminologia Anatomica was codified in 1998
by professional associations of anatomists
• About 90% of medical terms from 1,200
Greek and Latin roots
• Naming confusion during the Renaissance
– same structures with different names in different countries
– structures named after people (eponyms)
• 1895 Nomina Anatomica (NA)
– rejected all eponyms
– each structure given a unique Latin name to be used worldwide
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Analyzing Medical Terms
• Terminology based on word elements
– lexicon of 400 word elements on the inside the back
cover of textbook
• Scientific terms
–
–
–
–
one root (stem) with core meaning
combining vowels join roots into a word
prefix modifies core meaning of root word
suffix modifies core meaning of root word
• Acronyms formed from first letter, or first few letters of
series of words
– Calmodulin comes from the phrase - calcium
modulating protein
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Useful Tables in Textbook
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Plural, Adjectival, and
Possessive Forms
• Plural forms not always easy
– ovary – ovaries, cortex – cortices, corpus – corpora, epididymis –
epididymides
• Adjectival form of same word
– brachium denotes ‘arm’
– brachii denotes ‘of the arm’
- digits – fingers and toes
- digiti – of a single finger or toe
- digitorum – of multiple fingers or toes
• 3 examples of positive, comparative, and superlative
degrees of comparison
• English – large, larger, and largest
• Latin - magnus means large, major means larger of 2, while maximus is largest
of 3 being compared
• Adjectives often follow the noun in a name
• foramen magnum or pectoralis major
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Importance of Precision
• Be precise in your terms
• Spell correctly
• Health Care professions demand the
same type of precision
• People’s lives will be in your hands
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Review of Major Themes
• Cell Theory
– All structure and function result from the activity of cells
• Homeostasis
– The purpose of most normal physiology is to maintain stable
conditions within the body
• Evolution
– The human body is a product of evolution
• Hierarchy of Structure
– Human structure can be viewed as a series of levels of complexity
• Unity of Form and Function
– Form and function complement each other; physiology cannot be
divorced from anatomy
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Medical Imaging
• Radiography (x rays)
– William Roentgen - 1885
– penetrate tissues to
darken photographic film
beneath the body
– dense tissue appears
white
– over half of all medical
imaging
– until 1960’s, it was the only
method widely available
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Medical Imaging
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• Radiopaque substances
– injected or swallowed
– fills hollow structures
• blood vessels
• intestinal tract
(b) Cerebral angiogram
Custom Medical Stock Photo, Inc.
Figure 1.13b
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Medical Imaging
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• Computed
Tomography (CT
scan)
– formerly called a CAT
scan
– low-intensity X rays
and computer analysis
• slice type image
• increased
sharpness of image
(c) Computed tomographic (CT) scan
© CNR/Phototake
Figure 1.13c
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Medical Imaging - Nuclear Medicine
• Positron Emission Tomography (PET scan)
– assesses metabolic state of tissue
– distinguished tissues most active at a
given moment
– mechanics
• inject radioactively labeled glucose
–
–
–
–
–
positrons and electrons collide
gamma rays given off
detected by sensor
analyzed by computer
image color shows which tissues
were using the most glucose at that moment
– damaged tissues appear dark
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Medical Imaging
• Magnetic Resonance
Imaging (MRI)
–
–
–
–
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slice type image
superior quality to CT scan
best for soft tissue
mechanics
• alignment & realignment of
hydrogen atoms with
magnetic field & radio waves
• varying levels of energy
given off used by computer
to produce an image
(e) Magnetic resonance image (MRI)
© Monte S. Buchsbaum, Mt. Sinai School of Medicine, New York, NY
Figure 1.13e
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Medical Imaging
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• Sonography
– second oldest & second
most widely used
– mechanics
• high-frequency sound
waves echo back
from internal organs
(a)
– avoids harmful x rays
• obstetrics
• image not very sharp
(b)
© Alexander Tsiaras/Photo Researchers, Inc.; (inset): Ken Saladin
Figure 1.14
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