Chapter 1
Introduction to
Physiology
About this Chapter
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Definition of physiology
Review of organ systems
Function and process
Introduction to homeostasis
Ideas in physiology
Themes in physiology
The science of physiology
Levels of Organization
• Physiology defined
• Study of the normal functioning of a living
organism and its component parts
• Includes all its chemical and physical processes
• Literal “knowledge of nature” Aristole.
• Anatomy defined
• Study of structures
• Literal to dissect or take apart
• Organization of life
• The cell is the unit of life
• Cells, tissues, organs, organ systems, and
organisms
Levels of Organization
PHYSIOLOGY
CHEMISTRY
Atoms
MOLECULAR
BIOLOGY
Molecules
Cells
ECOLOGY
CELL
BIOLOGY
Tissues
Organs
Organ
systems
Organisms
Populations of
one species
Ecosystem of
different species
Biosphere
Figure 1-1
Levels of Organization - Human
Organ Systems in Review
Know Names, functions
and major components
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NIRMCRUDLES
Integumentary
Musculoskeletal
Respiratory
Digestive
Urinary
Reproductive
Circulatory / Cardiovascular
Nervous
Endocrine
Lymphatic / Immune
Organ
System
Integumentary
system
Major
Functions
Protection from environmental
hazards; temperature control
Skeletal
system
Support, protection of soft
tissues; mineral storage;
blood formation
Muscular
system
Locomotion, support, heat
production
Nervous
system
Directing immediate responses
to stimuli, usually by coordinating
the activities of other organ
systems
Endocrine
system
Directing long-term changes
in the activities of other organ
systems
Cardiovascular
system
Internal transport of cells and
dissolved materials, including
nutrients, wastes, and gases
Lymphatic
system
Defense against infection and
disease
Respiratory
system
Delivery of air to sites where gas
exchange can occur between
the air and circulating blood
Digestive
system
Processing of food and absorption
of organic nutrients, minerals,
vitamins, and water
Urinary
system
Elimination of excess water,
salts, and waste products;
control of pH
Reproductive
system
Production of sex cells and
hormones
Organ Systems in Review
• The integration between systems of the body
Integumentary System
Respiratory
system
Nervous
system
Circulatory
system
Endocrine
system
Digestive
system
Musculoskeletal
system
Urinary
system
Reproductive
system
Figure 1-2
Function versus Process
• Function explains the “why”
• Teleological approach
• Process or mechanism describes the “how”
• Mechanistic approach
• Red blood cell example
• “Because cells need oxygen and red blood cells
bring it to them.”
• “Oxygen binds to hemoglobin molecules
contained in the red blood cells.”
Homeostasis
• Adaptive significance of functions
• Keeping internal environment stable
• Cell
• Intracellular fluid
• Extracellular fluid
• Outside world
Homeostasis
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Most cells contact extracellular fluid
Out out
Out
In
External environment
In in
of the body
Material enters
and leaves
the body
Material enters
and leaves
the body
Intracellular
fluid of
most cells
Extracellular fluid:
the internal environment
of the body
Figure 1-3
Homeostasis and Controls
• External or
internal change
• Loss of
homeostasis
• Sensed by
organism
• Physiological
attempt to
correct
• Negative
feedback loop
Homeostasis and Controls
• Successful
compensation
• Homeostasis
reestablished
• Failure to
compensate
• Illness
• Death
• Study of failure to
compensate is
pathophysiology
Homeostasis and Controls
Organism in
homeostasis
External
change
Internal
change
Internal change
results in
loss of homeostasis
Organism attempts
to compensate
Compensation fails
Illness or disease
Compensation succeeds
Wellness
Figure 1-4
Themes in Physiology
• Homeostasis
• Control systems
• Biological energy use
• Structure-function relationships
• Molecular interactions
• Mechanical properties of cells, tissues, and
organs
• Communication
• Chemical and electrical signals
Themes in Physiology
• A simple control system
Input
signal
Controller
Output
signal
Figure 1-5
Concept Mapping
• Organizational tool for relationships and
processes
• Schematic diagram of structure and function
• Cells, tissues, and organs
• Flow charts
• Diagram processes in sequence
Concept Mapping: Types of Maps
Person working
outside on a hot,
dry day
Loses body water
by evaporation
Body fluids become
more concentrated
Internal receptors
sense change in
internal concentration
Thirst pathways
stimulated
Person seeks out
and drinks water
Water added
to body fluids
decreases their
concentration
(b) A process map, or flow chart
Figure 1-6b