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Chapter 1
The Study of Body
Function
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Chapter 1 Outline
 Introduction
to Physiology
 Scientific Method
 Homeostasis
 The Primary Tissues
 Muscle Tissue
 Nervous Tissue
 Epithelial Tissue
 Connective Tissue
 Organs and Systems
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Human Physiology
Physiology:
study of how
body works to maintain life
Pathophysiology:
how
physiological processes are
altered in disease or injury
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Scientific Method
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Scientific Method
 1.
Form a testable hypothesis about observations
 2. Conduct and analyze experiments to test
hypothesis
 3. Draw conclusions about whether or not results
support hypothesis
 4. Develop a theory
= general statement explaining natural phenomena
that is based on proven hypotheses
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Testing of Hypotheses
Involves:
Experimental
and control groups
Quantitative measurements performed blindly
Analysis of data using statistics
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Using Scientific Method to Develop New
Drugs
 When
a new drug is suggested
by experiments:
Its effectiveness and toxicity
is tested first in tissue
culture, rats, mice
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Using Scientific Method to Develop New
Drugs
 If
effective and safe, clinical trials performed
Phase I Trials: Toxicity and metabolism
tested in healthy human volunteers
Phase II Trials: Effectiveness and toxicity
tested in target population
Phase III Trials: Widespread test of drug in
diverse population
Phase IV Trials: Drug is tested for other
potential uses
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Homeostasis
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Homeostasis
 Is
maintenance of a state of dynamic constancy
In which conditions are stabilized above and below
a physiological set point
By negative feedback loops
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Negative Feedback Loops
Sensor:
Detects
deviation from set point
Integrating center:
Determines response
Effector: Produces
response
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Homeostasis continued
 Regulatory
mechanisms:
Intrinsic control is built into
organ being regulated
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Homeostasis continued
 Regulatory
mechanisms:
Extrinsic control comes from outside of organ
E.g. body temperature is controlled by
antagonistic effects of sweating and shivering
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 Regulatory
Homeostasis continued
mechanisms:
Extrinsic control comes from outside of organ
E.g. hormones control blood glucose levels
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Homeostasis continued
 Regulatory
mechanisms:
Positive feedback is rare because it amplifies
changes
It is involved in producing blood clots
In females it is used to create the LH surge that
causes ovulation
Positive feedback between the uterus and
oxytocin secretion occurs during labor
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Homeostasis continued
 Regulatory
mechanisms:
Negative feedback loops control blood pressure
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Negative Feedback Hormonal Control of
Blood Glucose
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The Primary Tissues
(includes muscle,
nervous, epithelial and
connective tissues)
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Muscle Tissue
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Muscle Tissue
Specialized
for contraction
3 types: skeletal, cardiac, smooth
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Skeletal Muscle
 Is
striated; voluntary
 Each fiber:
 Forms by fusion of
embryonic myoblasts
 Allowing it to
become large and
multinucleated
 Is individually
controlled
 Lines up in parallel
with other fibers to
form bundles
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 Myocardial
Cardiac Muscle
celIs:
 Are short, striated and involuntary
 Are branched to form a continuous fabric
 Have intercalated discs between cells that provide
mechanical and electrical interconnections
 Are not individually controlled
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Smooth Muscle
 Is
not striated; is involuntary
 Found in many organs, tissues
 Controlled by ANS
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Nervous Tissue
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Nervous Tissue
 Consists
of neurons and supporting or glial cells
 Neurons are specialized for conducting electrical
signals
Have a cell body, dendrites and axon
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Nervous Tissue continued
 Cell
body contains nucleus; is metabolic center
 Dendrites: highly branched extensions off cell body
Receive inputs from other neurons
 Axon: single, long extension off cell body
Conducts nerve impulses to other cells
 Supporting/Glial cells provide physical and functional
support for neurons
5X more abundant than neurons
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Epithelial Tissue
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Epithelial Tissue
 Lines
and covers body surfaces
 Consists of cells that form membranes and glands
 Regularly replaced
 Squamous epithelial cells are flattened
 Columnar epithelial cells are taller than wide
 Cuboidal epithelial cells are cube-shaped
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Epithelial Tissue continued
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Epithelial Tissue continued
 Simple
membranes are one cell thick
Specialized for transport
 Stratified has a number of layers
Specialized for protection
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Epithelial Tissue continued
 Non-keratinized
stratified squamous consists of living
cells (Fig 1.13)
 Keratinized stratified squamous has outer layer of
dead cells
Cells contain water-resistant keratin
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Epithelial Tissue continued
 Cells
are joined by junctional complexes, which
increase strength and create barrier
 Separated from underlying tissue by basement
membrane
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Exocrine Glands
 Derived
from epithelial cells
 Secrete onto epithelium via ducts
 Can be simple tubes or clusters called acini
 Whose secretion is controlled by surrounding myoepithelial
cells
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Connective Tissue
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Connective Tissue
 Has
lots of extracellular material deposited in space
between its cells
 Includes connective tissue proper, cartilage, bone and
blood
 Loose connective tissue consists of collagen (fibrous
proteins) and tissue fluid
E.g. dermis of skin
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Connective Tissue Proper
 Dense
fibrous
connective tissue is
packed with fibers of
collagen
Can be regularly
arranged as in
tendons
Or irregularly
oriented as in
capsules, sheaths
(Fig 1.16)
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Connective Tissue - Adipose
Specialized
for fat synthesis, breakdown and storage
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Connective Tissue - Cartilage
Specialized
for support, protection
Made of chondrocytes and elastic extracellular
material
Serves as precursor for bone
Forms articular surfaces for joints
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Connective Tissue - Bone
 Formed
as concentric
layers of calcified
material
 Contains 3 cell types:
Osteoblasts: boneforming cells
Osteocytes: trapped,
inactive osteoblasts
Osteoclasts: the
bone resorbing cells
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Organs and Systems
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Organs
Are
anatomical and functional
units made of two or more
primary tissues
Systems are groups of
organs working together to
maintain homeostasis
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Skin—The Largest Organ
Has
an outer layer of protective cornified epidermis
Next layer is dermis, which contains connective tissue,
glands, blood vessels, nerves
Inner layer is hypodermis, which contains fat
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Stem Cells
Most
cells in organs are highly specialized or
differentiated
Many organs retain small populations of adult stem
cells
These are less differentiated; can become many cell
types
E.g. bone marrow stem cells can give rise to all of
the different blood cell types
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Stem Cells continued
Hair follicle stem
cells can form
the hair shaft,
root sheath,
sebaceous
glands and
epidermis
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Body-Fluid Compartments
Body
has intracellular and extracellular compartments
Intracellular is inside cells
Extracellular is outside cells
Separated by cell’s outer membrane
Extracellular is composed of blood plasma and
interstitial fluid
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