CHAPTER 1: Homeostasis: a Framework for Human Physiology
Structural Characteristics
Physiology = study of how living organisms function
o Hierarchy of structural organization
Atoms > molecules > cells > tissues >
...
CHAPTER 1: Homeostasis: a Framework for Human Physiology
Structural Characteristics
Physiology = study of how living organisms function
o Hierarchy of structural organization
Atoms > molecules > cells > tissues > organs > organ systems > organism
o Integrated physiological function
Understanding how changes in function at each level lead to a whole-body response
o Interrelationships between structure & function
Cell division
Multiplication of cells
Only a spherical mass of identical cells without cell differentiation
Cell differentiation
Unspecialized cell > specialized cell
200 distinct kinds of cells in the body
Classified in broad types of function
o Muscle cells
o Neurons
o Epithelial cells
o Connective tissue cells
Tissues
o Muscle tissue and cells
Function
Mechanical force generation
Types
Skeletal
o Voluntary
Cardiac
o Involuntary
o Found only in the heart
Smooth
o Involuntary
o Make up walls of tubes in the body (blood vessels, gastrointestinal tract, etc.)
o Contraction helps to move substances along
Differ in shape, mechanisms controlling contractile activity, and in location in various
organs
o Nervous tissue and neurons
Function
Communication via generation of electrical signals
o A neuron signal may signal other neurons or it may stimulate a gland cell to
secrete substances
o Epithelial tissue and cells
Function
Barrier: coverings of internal & external surfaces
o Compartmentalization
o Structures
Basement membrane: protein layer of which the epithelial cells rest on,
anchoring the tissue
Basolateral side: side of cell anchored to basement membrane
Apical (luminal) side: side of cell that faces the interior of a structure
Tight junctions
Selective barriers
Regulate exchange of molecules
Selective secretion & absorption of ions & organic molecules
Protection
Type of epithelium (simple or stratified) that forms a region reflects the function of that epithelium
o Connective tissue and cells
Function
“Connect”, anchor, & support different parts of the body
Formation of extracellular matrix
o Collagen fibers and elastin (protein) fibers, polysaccharides
o Provides scaffolding for cellular attachments
o Cell signaling
Types
Tendons, ligaments, blood, bone, cartilage, & adipose tissue
Organs: discrete structure that performs a specific function
o 2+ types of tissue
Often comprised of all 4 cell/tissue types
Arranged in sheets, tubes, layers, bundles, & strips
o Functional unit: “working unit” of an organ
Smaller, similar subunits to the organ
EX: nephrons in kidneys
Organ system: several organs working together t
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