Transcript Chapter 1 - HCC Learning Web

Chapter 1
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Copyright (c) The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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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 2
• Physical examination
– palpation, auscultation, percussion
• Gross anatomy
– visible with naked eye
• Histology
– examination of cells with microscope
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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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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 2
• 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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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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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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END of Chapter 1
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