Download Human Anatomy & Physiology I BIO 201

Human Anatomy & Physiology I
BIO 201
Major Themes of Anatomy &
Physiology
Chapter 1
By
Abdul Fellah, Ph.D.
Major Themes of Anatomy &
Physiology
• Form and Function
• Origins of Biomedical Science
• Scientific Method
• Human Origins and Adaptations
• Human Structure
• Human Function
• Language of Medicine
Anatomy - The Study of Form
• Observation of surface structure
• Cadaver dissection is cutting & separation of
organs to study their relationships
• Comparative anatomy is the study of more than
one species to analyze evolutionary trends
• Physical examination
– palpation, auscultation, percussion
• Gross anatomy is what is visible with naked eye
• Histology is examination of cells with microscope
Physiology - The Study of Function
• Study of bodily functions by use of methods
of experimental science
• Comparative physiology involves the study of
different species
• Basis for the development of new drugs and
medical procedures
Beginnings of Medicine
• Physicians in Mesopotamia & Egypt 3000
years ago used herbal drugs, salts &
physical therapy
• Greek physician Hippocrates established
a code of ethics & urged physicians to
seek causes of disease
• Aristotle called causes for disease
physiologi & said that complex structures
are built from simpler parts
Beginnings of Medicine
• 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
Birth of Modern Medicine
• Little advancement during the Middle ages since
medicine was taught as dogma with no new ideas
• Avicenna from Muslim world supported free inquiry
over authority
– wrote The Canon of Medicine, used in medical schools
until 16th century
• Vesalius published accurate gross anatomy atlas
(1543)
• Harvey realized blood flow out from heart & back in
1628
• Leeuwenhoek invented microscope to look at fabrics
(1632-1723)
Birth of Modern Medicine
• Hooke (1665) and Zeiss (1860) developed &
improved compound microscope (described
plant cell walls in 1665)
• Schleiden & Schwann thought that all
organisms were composed of cells -- cell
theory of 1839
• Clinical practice was in dismal state
– bleeding patients to remove toxins, operate with
dirty hands, no anesthesia for amputations
Early Microscopes
Living in a Revolution
• Pioneers in 19th & 20th centuries
– established scientific way of thinking
– replaced superstition with natural laws
– momentous discoveries
• germ theory of disease
• heredity & structure of DNA
• Now at threshold of modern biomedical science
– technology enhanced diagnostic ability & life-support
strategies
– genetic revolution --library of the molecular structure of
every human gene is finished
• Gene therapy being used to treat disease
Scientific Method
• Bacon (1561-1626) and Descartes (1596-1650)
– were not scientists but did invent new habits of scientific
thought
• scientific method as habits of disciplined creativity,
careful observations, logical thinking & analysis of
observations
• way of seeking trends & drawing generalizations
• Convinced governments of England & France to
form academies of science that still exist today
• Scientific way of thinking based on assumptions &
methods that are reliable, objective & testable
Inductive Method
• First described by philosopher Francis Bacon
• Making observations until capable of drawing
generalizations and making predictions
– anatomy is a product of inductive method
• Proof in science can not go past “proved
beyond reasonable doubt”
– reliable methods of observation
– tested and confirmed repeatedly
– not falsified by any credible observation
• In science, all truth is tentative
Hypothetico-Deductive Method
• Physiological knowledge gained by this
method
• Ask a question and formulate a hypothesis -an educated possible answer
• Good hypothesis
– consistent with what is already known
– capable of being tested and falsified with certain evidence
• If nothing could prove it wrong, it is not a
scientific belief
• Hypotheses are written as If-Then predictions
– modified and rewritten after testing
Experimental Design
• Sufficient sample size to prevent chance event
• Control group and treatment group receive the
same treatment except for the variable being
tested
• Prevention of psychosomatic effects
– use of placebo in control group
• Experimenter bias
– prevented with double-blind study
• Statistical testing to be sure the difference
between groups was not random, but was due
to variable being tested
Peer Review
• Critical evaluation by other experts in
the field
– prior to funding
– verification and repeatability of results
• Ensures honesty, objectivity & quality
in science
Facts, Laws and Theories
• Scientific fact is information that can be
independently verified by any trained person
– iron deficiency leads to anemia
• Law of nature is a description of the way
matter and energy behave
– resulting from inductive reasoning & repeated observations
– written as verbal statements or mathematical formulae
• Theory is a summary of conclusions drawn
from observable facts
– it provides explanations and predictions
– sliding filament theory of muscle contraction
Human Origins and Adaptations
• Charles Darwin’s theory of natural selection
explains how species originate and change
through time
– On the Origin of Species by Means of Natural
Selection (1859)
– The Descent of Man (1871) discussed human
evolution & our relationships to other animals
• Changed our view of our origin, our nature &
our place in the universe
• Good understanding of our evolutionary
history deepens our understanding of form &
function
Evolution, Selection, and Adaptation
• Evolution is change in genetic composition of a
population of organisms
– development of bacterial resistance to antibiotics,
new strains of AIDS virus and emergence of new
species
• Theory of natural selection
– some individuals have hereditary advantages
(adaptations) enabling them to produce more
offspring
– if they pass these characteristics on it brings about
a genetic change in the population (evolution)
– forces that favor some individuals over others are
called selection pressures -- climate, disease, etc.
Adaptations
• Adaptations are useful features that evolved in
response to selection pressures
• DNA hybridization suggests a difference of only
1.6% in DNA structure between humans &
chimpanzees
• Evolutionary developments help explain some
aspects of our anatomy (vestigial organs)
– piloerector muscle in the skin have no use
– auricularis muscles do not move in most people
• Evolutionary relationships help us chose animals for
biomedical research
– rats & mice used extensively
Primate Adaptations
• Some human features can be traced to the earliest
primates
• Squirrel-sized, insect-eating mammals became
arboreal probably due to safety, food supply & lack
of competition
– shoulder became more mobile (reach any direction)
– thumbs became opposable to encircle branches with
thumb & fingers (prehensile)
– forward-facing eyes provide depth perception
• judge distances accurately for leaping & catching prey
– color vision to distinguish ripe fruit
– larger brains & good memory to remember food sources
Walking Upright
• African forest became grassland 5 million years ago
• Bipedalism (standing & walking on 2 legs) evolved
– spot predators, carry food or infants
• Adaptations for bipedalism
– pelvis, femur, knee, great toe, arch, skull, vertebrae, etc.
• Australopithecus (2.5mya) gave rise Homo habilis
– taller, larger brain volume, speech, tool-making
• Homo erectus (1.1mya) and Homo sapiens (.3mya)
• Homo sapiens include Neanderthal & Cro-Magnon
• Evolutionary medicine traces our diseases to
evolutionary past
Primate Phylogeny
Human Structure
• Hierarchy of complexity
– organism is composed of organ
systems
– organ systems composed of
organs
– organs composed of tissues
– tissues composed of cells
– organelles composed of
molecules
– molecules composed of atoms
– Atoms compose molecules
• Reductionism versus holism
Anatomical Variation
• No 2 humans are exactly alike
• Missing organs
– palmaris longus or plantaris muscles
• More or less organs than normal
– 2 spleens, single kidney, 6 or 4 lumbar vertebrae
• Variation in organ locations (situs inversus,
dextrocardia, situs perversus)
Human Function
• Characteristics of life
– organization
– cellular composition
– excretion
– metabolism
– responsiveness and movement
– homeostasis
– development (growth or differentiation)
– reproduction
– evolution
• Clinical death is no brain waves for 24 hours
Physiological Variation
• Differs with sex, age, diet, weight, degree of
physical activity
• Typical human values
– reference man
• 22 years old, 154 lbs, light physical activity
• 2800 kcal/day
– reference woman
• same as man except 128 lbs and 2000 kcal/day
Homeostasis
• Hippocrates noted that body normally returns
to a state of equilibrium by itself
– needs to detect the change & oppose it
• Walter Cannon (1871-1945) coined the term
homeostasis indicating stable internal
environment
• Internal environment described as dynamic
equilibrium
– fluctuates within a range around a certain set point
• Loss of homeostatic control causes illness or
death
Negative Feedback Loops
• Mechanism to keep a variable close to its set
point
• Body senses a change & activates
mechanisms to reverse it
Negative Feedback, Set Point
• Room temperature does not stay at set point
of 68 degrees -- it only averages 68 degrees
Human Thermoregulation
• Blood temperature sensing nerve cells in base of
brain control shivering, sweating & vasomotor
activity
– vasodilation with heat & vasoconstriction with cold
• Evaporation of water & heat radiation occur
Control of Blood Pressure
• Rise in blood pressure detected
– stretch receptors in wall of heart and
major arteries
• Nerve signals travel to cardiac center
in brainstem
• Nerve signals slow heart and lower
blood pressure
Structures Needed for
Feedback Loop
• Receptor = structure that senses change
– stretch receptors in heart & large blood vessels
send information of an elevated BP to integrator
• Integrator = control center
– cardiac center in brainstem that signals heart to
slow
• Effector = structures that carry out commands
of the control center
– heart slows and BP decreases
– sweating begins and evaporation cools the body
Positive Feedback Loops
• Physiological change that leads to an even greater
change in the same direction (self-amplifying)
• Normal way of producing rapid changes
– birth, blood clotting, protein digestion, generation of nerve
signals
Life-Threatening Fever
• If temperature rises above 108 degrees due
to bacterial infection
– metabolic rate
increases causing
body to produce
heat faster still
• Temperature
increases &
cycle repeats
• Fatal at 113
degrees
History of Anatomical Terminology
• Most medical terms are formed from Greek and Latin
roots
• Fast-paced anatomical discoveries during the
Renaissance resulted in naming confusion
– different countries naming same structures with different
names
– structures being named after people (eponyms)
• Anatomy meetings in 1895 began search for uniform
international terminology
– Nomina Anatomica (NA) rejected all eponyms
• gave each structure a unique Latin name to be used worldwide
– Terminologia Anatomica was codified in 1998
Analyzing Medical Terms
• Medical terminology based on word elements
– lexicon of 400 common word elements in back of
book
• Scientific terms are composed of the
following elements
– at least one root (stem) that bears the core
meaning
– combining vowels that join roots together
– prefix that modifies the core meaning of the word
– suffix that modifies the core meaning of the word
• acronyms – words composed of the first few
letters of a series of words
Useful Tables in Textbook
Review of Major Themes
• Unifying principles behind all aspects of
human anatomy and physiology
– cell theory: all structure & function result from the
activity of cells
– homeostasis: maintaining stable conditions within
the body
– evolution: the body is a product of evolution,
molded by years of natural selection
– hierarchy of structure: levels of complexity
– unity of form and function: physiology can not be
separated from anatomy
Medical Imaging
• Radiography
– x-rays discovered (William Roentgen) in 1885
– penetrate soft tissues & darken photographic
film on other side of the body
– dense tissue (bone, teeth and tumors) are not
penetrated so photographic film remains white
– radiopaque substances can be either injected
(angiography) or swallowed for examination
of the gastrointestinal tract
• Sonography
– high-frequency ultrasound waves echoes
back from internal organs
– obstetrics uses to locate placenta, evaluate fetal
age, position and development
Medical Imaging
• Computed Tomography (CT scan)
– low-intensity X rays applied to the body
– computer analysis produces an image of a
slice of the body about as thin as a coin
– tumors, aneurysms, hemorrhages, kidney
stones, etc
• Magnetic Resonance Imaging (MRI)
– magnetic field aligns hydrogen atoms; radio
waves realign the atoms; when radio is
turned off the atoms give off energy
depending on tissue type
– computer analysis produces a “slice” type
image
– better for soft tissue analysis than CT
Medical Imaging
• Positron Emission Tomography (PET scan)
– assesses the metabolic state of a tissue
– injection of radioactively labeled glucose emits
positrons
– colliding positrons & electrons
give off gamma rays that are
analyzed by computer
– color image of glucose usage at
that moment
• extent of damaged heart tissue
• activity of brain of neurology patients
Basic Anatomical Terminology
• Anatomical position
• Regions of the body
• Anatomical planes, sections and directional terms
Anatomical Position
• Standardized position from which to describe
directional terms
–
–
–
–
–
–
standing upright
facing the observer, head level
eyes facing forward
feet flat on the floor
arms at the sides
palms turned forward
• Prone position = lying face down
• Supine position = lying face up
anatomical position?
Common Regional Names
• Clinical terminology based on a Greek or Latin root word.
Planes and Sections
• A plane is an imaginary
flat surface that passes
through the body.
• A section is one of the
2 surfaces (pieces) that
results when the body
is cut by a plane
passing through it.
Sagittal Plane
• Sagittal plane
– divides the body or an
organ into left and
right sides
• Midsagittal plane
– produces equal halves
• Parasagittal plane
– produces unequal
halves
Other Planes and Sections
• Frontal or coronal plane
– divides the body or an organ
into front (anterior) and back
(posterior) portions
• Transverse(cross-sectional) or
horizontal plane
– divides the body or an organ
into upper (superior) or lower
(inferior) portions
• Oblique plane
– some combination of 2 other
planes
Planes and Sections of the Brain
(3-D anatomical relationships revealed)
• Horizontal Plane
• Frontal Plane
• Midsagittal Plane
Major Directional Terms
• See Definitions page 14
Superior or Inferior
• Superior
– towards the head
– The eyes are superior
to the mouth.
• Inferior
– away from the head
– The stomach is
inferior to the heart.
Dorsal or Ventral
• Dorsal or Posterior
– at the back of the body
– The brain is posterior to
the forehead.
• Ventral or Anterior
– at the front of the body
– The sternum is anterior to
the heart.
Medial or Lateral
• Medial
– nearer to the midline of the body
– The heart lies medial to the lungs.
• Lateral
– farther from the midline of the body
– The thumb is on the lateral side of the
hand.
Proximal or Distal
• Proximal
– nearer to the attachment of the
limb to the trunk
– The knee is proximal to the
ankle.
• Distal
– farther from the attachment of
the limb to the trunk
– The wrist is distal to the elbow.
Dorsal Body Cavity
• Near dorsal surface of
body
• 2 subdivisions
– cranial cavity
• holds the brain
• formed by skull
– vertebral or spinal canal
• contains the spinal cord
• formed by vertebral
column
• Meninges line dorsal
body cavity
Ventral Body Cavity
• Near ventral surface of
body
• 2 subdivisions
– thoracic cavity above
diaphragm
– abdominopelvic cavity
below diaphragm
• Diaphragm = large,
dome-shaped muscle
• Organs called viscera
• Organs covered with
serous membrane
Abdominopelvic Cavity
• Inferior portion of ventral body cavity below diaphragm
• Encircled by abdominal wall, bones & muscles of
pelvis
Thoracic Cavity
• Encircled by ribs, sternum, vertebral column and muscle
• Divided into 2 pleural cavities by mediastinum
• Mediastinum contains all thoracic organs except lungs
Mediastinum
• Midline wall of tissue that contains heart and great
vessels, esophagus, trachea and thymus.
Serous Membranes
• Thin slippery membrane lines body cavities not
open to the outside
– parietal layer lines walls of cavities
– visceral layer covers viscera within the cavities
• Serous fluid reduces friction
Pleural & Pericardial Cavities
• Visceral pleura clings to surface of lungs --- Parietal pleura
lines chest wall
• Visceral pericardium covers heart --- Parietal pericardium
lines pericardial sac
Peritoneum
• Visceral peritoneum --- serous membrane that covers the
abdominal viscera
• Parietal peritoneum --- serous membrane that lines the
abdominal wall
Abdominopelvic Regions & Quadrants
• Describe locations of organs or source of pain
• Tic-tac-toe grid or intersecting lines through navel