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Chapter 1
*APR Lecture
PowerPoint
Major Themes of
Anatomy and
Physiology
*See separate FlexArt PowerPoint slides for all
figures and tables preinserted into PowerPoint
without notes.
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Introduction
• Anatomy and physiology (A&P) is about human
structure and function—the biology of the human
body
• We want to know how our body works!
• A&P is a foundation for advanced study in health
care, exercise physiology, pathophysiology, and
other health-care-related fields
• Considers the historical development and a
central concept of physiology—homeostasis
1-2
The Scope of Anatomy
and Physiology
• Expected Learning Outcomes
– Define anatomy and physiology and relate
them to each other.
– Describe several ways of studying human
anatomy.
– Define a few subdisciplines of human
physiology.
1-3
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
Figure 1.1
– Study of more than one
species in order to examine
structural similarities and
differences, and analyze
evolutionary trends
1-4
Cadaver Dissection
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
– View molecular detail under electron microscope
• Histopathology
– Microscopic examination of tissues for signs of disease
1-6
Exploratory Surgery
Cytology
Histology
Medical Imaging
Gross Anatomy
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
procedures
1-8
The Origins of
Biomedical Sciences
• Expected Learning Outcomes
– Give examples of how modern biomedical
science emerged from an era of superstition
and authoritarianism.
– Describe the contributions of some key
people who helped to bring about the
transformation.
1-9
Greek and Roman Legacy
• Physicians in Mesopotamia and Egypt
– 3,000 years ago used herbal drugs, salts, and
physical therapy
• Hippocrates, the 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
1-10
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
1-11
Greek and Roman Legacy
• Claudius Galen
– Physician to the Roman gladiators
– Did animal dissections since use of cadavers was
banned in his time
– Saw science as a method of discover, 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”
1-12
The 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
years
1-13
The Birth of Modern Medicine
• 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, De Humani
Corporis Fabrica (On the Structure of the Human
Body) in 1543
1-14
The Birth of Modern Medicine
• 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, they 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
1-15
Early Medical Illustrations
Figure 1.2
Figure 1.3
1-16
The Birth of Modern Medicine
• Robert Hooke
– Made many improvements to
the compound microscope—
two lenses: ocular 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 name “cells”
Figure 1.4
– Published first
comprehensive book of
microscopy (Micrographia) in
1665
1-17
The Birth of Modern Medicine
• 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
• Carl Zeiss and Ernst Abbe
– Greatly improved compound microscopes
– Added condenser and superior optics
• Eliminated blurry edges (spherical aberration) and
rainbowlike distortions (chromatic aberration)
1-18
Cell Theory
The Birth of Modern Medicine
• 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
1-20
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
1-21
Scientific Method
• Expected Learning Outcomes
– Describe the inductive and hypothetico–
deductive methods of obtaining scientific
knowledge.
– Describe some aspects of experimental
design that help to ensure objective and
reliable results.
– Explain what is meant by hypothesis, fact,
law, and theory in science.
1-22
Scientific Method
• Francis Bacon, in England, and René
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 that still exist today
• Science and scientific methods
– Set standards for truth
1-23
The 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”
1-24
The 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
1-25
The Hypothetico–Deductive Method
• 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
questions: written as “if–then” statements
1-26
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
– Use of placebo in control group
1-27
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
1-28
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
1-29
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
1-30
Human Origins and Adaptations
• Expected Learning Outcomes
– Explain why evolution is relevant to
understanding human form and function.
– Define evolution and natural selection.
– Describe some human characteristics that
can be attributed to the tree-dwelling habits of
earlier primates.
– Describe some human characteristics that
evolved later in connection with upright
walking.
1-31
Human Origins and Adaptations
• Charles Darwin
– On the Origin of Species by Means of Natural
Selection (1859)—‟the book that shook the world”
– The Descent of Man (1871)—human evolution,
anatomy and behavior, relationship to other animals
• Theory of natural selection
– How species originate and change through time
– Changed prevailing view of our origin, nature and
our place in the universe
– Increases understanding of human form and
function
1-32
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
– Selection pressures—natural forces that promote the
reproductive success of some individuals more than
others
1-33
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
1-34
Evolution, Selection,
and Adaptation
• 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
1-35
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
1-36
Our Basic Primate Adaptations
• 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
1-37
Our Basic Primate Adaptations
• Adaptations for arboreal (treetop) lifestyle
– 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
1-38
Our Basic Primate Adaptations
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Monkey
Human
Figure 1.5
Figure 1.6
1-39
Walking Upright
• African forest became grassland 4 to 5 million
years ago
– Producing more predators and less protection
• Bipedalism—standing and walking on two legs
– Helps spot predators, carry food or infants
• Adaptations for bipedalism
– Skeletal and muscular modifications
– Increased brain volume
– Family life and social changes
1-40
Walking Upright
• Australopithecus—oldest bipedal primate
• Homo genus (appeared 2.5 million years ago)
– Taller, larger brain volume, probable speech, toolmaking
• Homo erectus (appeared 1.8 million years ago)
– Migrated from Africa to parts Asia
1-41
Walking Upright
• 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
1-42
Human Structure
• Expected Learning Outcomes
– List the levels of human structure from the most
complex to the simplest.
– Discuss the value of both reductionistic and holistic
viewpoints to understanding human form and
function.
– Discuss the clinical significance of anatomical
variation among humans.
1-43
The Hierarchy of Complexity
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Organism is composed of
organ systems
Organism
• Organ systems composed of
organs
• Organs composed of tissues
• Tissues composed of cells
Organ system
Tissue
Organ
• Cells composed of organelles
Cell
• Organelles composed of
molecules
• Molecules composed of
atoms
Macromolecule
Organelle
Atom
Molecule
Figure 1.7
1-44
The 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
1-45
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)
1-46
Anatomical Variation
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Normal
Pelvic kidney
Horseshoe kidney
Figure 1.8
Normal
1-47
Variations in branches of the aorta
Anatomical Variation
Abdominal Aorta and Common Iliac Arteries
Human Function
• Expected Learning Outcomes
– State the characteristics that distinguish living
organisms from nonliving objects.
– Explain the importance of defining a reference
man and woman.
– Define homeostasis and explain why this concept
is central to physiology.
– Define negative feedback, give an example of it,
and explain its importance to homeostasis.
– Define positive feedback and give examples of its
beneficial and harmful effects.
1-49
Characteristics of Life
• Organization—living things exhibit a higher
level of organization than the nonliving world
around them
• Cellular composition—living matter is always
compartmentalized into one or more cells
• Metabolism—sum of all internal chemical
change: anabolism, catabolism, and excretion
• Responsiveness and movement—sense and
react to stimuli (responsiveness, irritability, or
excitability)
1-50
Characteristics of Life
• Homeostasis—maintaining relatively stable
internal conditions
• Development—differentiation and growth
• Reproduction—producing copies of
themselves; pass genes to offspring
• Evolution—mutations: changes in genetic
structure
1-51
Physiological Variation
• Sex, age, diet, weight, physical activity
• Typical physiological values
– Reference man
• 22 years old, 154 lb, light physical activity
• Consumes 2,800 kcal/day
– Reference woman
• Same as man except 128 lb and 2,000 kcal/day
• Failure to consider variation can lead to
overmedication of elderly or medicating
women on the basis of research done on
men
1-52
Homeostasis and Negative Feedback
• 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°–99°F despite variations
in external temperature
1-53
Homeostasis and Negative Feedback
• 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
1-54
Negative Feedback Loop
• Body senses a change and activates mechanisms to reverse it—
dynamic equilibrium
• Because feedback mechanisms alter the original changes that triggered
them (temperature, for example), they are called feedback loops
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Room temperature
fallsto66В°F(19В°C)
1
C10В°
15В°20В°25В°
6 Room cools down
F50В°
60В°70В°80В°
2
C10В°
15В°20В°25В°
Thermost atactivates
furnace
F50В°
60В°70В°80В°
Figure 1.9a
5 Thermostat shuts
off furnace
4 Room temperature
rises to 70В°F (21В°C)
3 Heat output
(a)
1-55
Negative Feedback
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Room temperature (oF)
75
(b)
Furnace turned
off at 70 oF
70
Set point 68 oF
65
Furnace turned
on at 66 oF
60
Figure 1.9b
Time
• Example: Room temperature does not stay at set point
of 68°F—it only averages 68°F
1-56
Negative Feedback
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Core body temperature
Sweating
37.5 oC
(99.5
oF)
Vasodilation
37.0 oC
(98.6
oF)
36.5 oC
(97.7
oF)
Set point
Vasoconstriction
Figure 1.10
Time
Shivering
• Example: Brain senses change in blood temperature
– If too warm, vessels dilate (vasodilation) in the skin and
sweating begins (heat-losing mechanism)
– If too cold, vessels in the skin constrict (vasoconstriction)
and shivering begins (heat-gaining mechanism)
1-57
Homeostatis and Negative Feedback
• Sitting up in bed causes a drop in blood pressure in
the head and upper torso region (local imbalance in
homeostasis); detected by baroreceptors
• Baroreceptors (sensory nerve endings) in the
arteries near the heart alert the cardiac center in
the brainstem. They transmit to the cardiac center
1-58
Homeostatis and Negative Feedback
• Cardiac center sends nerve signals that increase
the heart rate and return the blood pressure to
normal; regulates heart rate
• Failure of this to feedback loop may produce
dizziness in the elderly
1-59
Postural Change in Blood Pressure
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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
Homeostasis and Negative Feedback
• Receptor—senses change in the body (e.g.,
stretch receptors that monitor blood pressure)
• Integrating (control) center—control center
that processes the sensory information,
“makes a decision,” and directs the response
(e.g., cardiac center of the brain)
• Effector—carries out the final corrective
action to restore homeostasis (e.g., cell or
organ)
1-61
Positive Feedback and Rapid Change
• 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
1-62
Positive Feedback and Rapid Change
• During birth, the head of the fetus pushes
against the cervix and stimulates its
nerve endings
– Hormone oxytocin is secreted from the pituitary
gland
– Oxytocin travels through the bloodstream to the
uterus stimulating it to contract
– This action pushes the fetus downward toward
cervix, thus stimulating the cervix more, causing
the positive feedback loop to be repeated
1-63
Positive Feedback Loops
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
3 Brain stimulates
pituitary gland to
secrete oxytocin
4
Oxytocin stimulates uterine
contractions and pushes
fetus toward cervix
2 Nerve impulses
from cervix
transmitted
to brain
1 Head of fetus
pushes against cervix
1-64
Positive Feedback and Rapid Change
• Fever > 104°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°F
1-65
The Language of Medicine
• Expected Learning Outcomes
– Explain why modern anatomical terminology is so
heavily based on Greek and Latin.
– Recognize eponyms when you see them.
– Describe the efforts to achieve an internationally
uniform anatomical terminology.
– Break medical terms down into their basic word
elements.
– State some reasons why the literal meaning of a word
may not lend insight into its definition.
– Relate singular noun forms to their plural and
adjectival forms.
– Discuss why precise spelling is important in anatomy
and physiology.
1-66
The History of
Anatomical Terminology
• Standard international anatomical terminology
– Terminologia Anatomica (TA) was codified in 1998
by professional associations of anatomists
• About 90% of medical terms from 1,200
Greek and Latin roots
1-67
The History of
Anatomical Terminology
• 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
1-68
Analyzing Medical Terms
• Terminology based on word elements
– Lexicon of 400 word elements on the inside 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
1-69
Analyzing Medical Terms
• Acronyms formed from first letter, or first few
letters, of series of words
– Calmodulin comes from the phrase “calciummodulating protein”
1-70
Plural, Adjectival, and
Possessive Forms
1-71
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”
Digiti—of a single finger or toe
Digits—fingers and toes
Digitorum—of multiple fingers or toes
1-72
Plural, Adjectival, and
Possessive Forms
• Three examples of positive, comparative, and
superlative degrees of comparison
• English: large, larger, and largest
• Latin: magnus means “large,” major means “larger of
two,” while maximus means “largest of three being
compared”
• Adjectives often follow the noun in a name
• Examples: foramen magnum or pectoralis major
1-73
Pronunciation
• Simple pronunciation guides for many terms
are given when terms are first introduced
• Go to the Anatomy & Physiology/Revealed
website for this book to hear pronunciation of
most anatomical terms!
– http://www.mhhe.com/sem/apr/
1-74
The 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
1-75
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
1-76
Medical Imaging
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Radiography (X-rays)
– William Roentgen’s
discovery in 1885
– Penetrate tissues to
darken photographic film
beneath the body
– Dense tissue appears
white
– Over half of all medical
imaging
– Until 1960s, it was the
only method widely
available
(a) X-ray (radiograph)
В© U.H.B. Trust/Tony Stone Images/Getty Imagese
Figure 1.13a
1-77
Medical Imaging
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
• Radiopaque substances
– Injected or swallowed
– Fills hollow structures
• Blood vessels
• Intestinal tract
Figure 1.13b
(b Cerebral angiogram
Custom Medical Stock Photos, Inc.
1-78
Medical Imaging
• Computed
tomography (CT scan)
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
– Formerly called a CAT
scan
– Low-intensity X-rays and
computer analysis
• Slice-type image
• Increased sharpness of
image
Figure 1.13c
(c) Computed tomographic (CT) scan
В© CNR/Phototake
1-79
Medical Imaging—Nuclear Medicine
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(d) Positron emission tomographic
(PET) scan
Tony Stone Images/Getty Images
Figure 1.13d
• 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 tissues using
the most glucose at that moment
• Damaged tissues appear dark
1-80
Medical Imaging
• Magnetic resonance
imaging (MRI)
–
–
–
–
Slice-type image
Superior quality to CT scan
Best for soft tissue
Mechanics
• Alignment and realignment
of hydrogen atoms with
magnetic field and radio
waves
• Varying levels of energy
given off used by computer
to produce an image
Copyright В© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(e) Magnetic resonance image (MRI)
В© Monte S. Buchsbaum, Mt. Sinai School of Medicine, New York, NY
Figure 1.13e
1-81
Medical Imaging
• Sonography
– Second oldest and
second most widely
used
– Mechanics
• High-frequency sound
waves echo back
from internal organs
– Avoids harmful X-rays
• Obstetrics
• Image not very sharp
Figure 1.14
1-82
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