Chapter 1
Introduction to Physiology and
Homeostasis
Anatomy and Physiology
• Anatomy
– Study of the structures of the body
• Physiology
– Study of the functions of cells, tissues, organs,
organ systems, and organisms
Levels of Organization
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Chemical and Cellular Organization
• Chemical level
– Atoms, molecules,
macromolecules
• Nucleic acids, Proteins,
Carbohydrates, Lipids
• Cellular level
– Cell
• The functional and structural
unit of life
• Basic and specialized functions
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– Specialized function requires
differentiation
– Stem cell anyone?
Tissue Level of Organization
• Tissue level
– Cells of similar shape and specialized function
• Four major tissue types
– Muscle
• Specialized for contracting and generating tension
– Nervous
• Specialized in impulse production and transmission
– Connective
• Specialized for connecting and supporting
– Epithelial
• Specialized for surface lining and exchange
Organs and Organ Systems
• Organ level
– Composed of two or more tissues that perform a
common function
• Organs system level
– Composed of two or more organs that work to
perform a common functions that is essential to
survival
• Digestive, respiratory, cardiovascular
• Human body contains 11 systems
The Organism
• Collection of body systems working together
to maintain life.
• Strive to maintain an internal balance
– Homeostasis
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Homeostasis
• The maintenance of a stable internal
environment.
– 37 degrees C, pH 7.3-7.4
– Other factors that are regulated?
• The internal environment is made up of the extra
cellular fluid or ECF
– Cells that are isolated from the external environment
can still exchange materials with the ECF
Homeostatic Control Systems
• Network of body components that operate to
maintain a given factor in the internal
environment relatively constant around an
optimal level
• Local (intrinsic) controls
– Inherent, or built into a particular organ
• Systemic (extrinsic) controls
– Outside of an organ
– Involves neural and endocrine regulation
• Coordinates various organs and systems
Negative Feedback Loops
• Maintain homeostasis by detecting a deviation
from a set point and act to restore that set
point
• Four components of a negative feedback loop
– Controlled variable
– Sensor
– Control center
– Effector
Other Regulatory Mechanisms
• Positive feedback loops
– Continues increasing an change
– Controlled variable moves in one direction
• Uterine contractions
• Feed forward mechanisms
– Anticipate change and responds to that change
before it happens