Chap 5 Flashcards
Tissues
Groups of similar cells and extracellular material with common function
Histology
Study of tissues
Four types of tissues with varied structure and function
Epithelial
Connective
Muscle
Nervous
Epithelium/epithelial tissue
One or more layers of closely packed cells
Contains little to no extracellular matrix
Avascular (no room for blood vessels)
**Lines body surfaces and body cavities **
Forms most glands
Polarity
Apical surface
Exposed to external environment or material in tube
Closest to the “white space”
May have microvilli or cilia
Lateral surface with intercellular junctions
Basal surface
Epithelium attached to underlying connective tissue
via the basement membrane
Physical protection
from dehydration, abrasion, destruction
Selective permeability
Non-permeable to some substances; Promotes passage of others
Secretions
Specialized secreting cells may be scattered or in small clusters
Sensations
Contain nerve endings; Touch, pressure, temperature, pain
Undergoes frequent cell division
Necessary due to environmental exposure; replacement of lost cells
Epithelia classification indicated by two-part name
Number of epithelial cell layers
Simple Stratified Pseudostratified
Epithelia classification indicated by two-part name
Shape of cells at apical surface
Squamous Cuboidal Columnar
Simple epithelium
ONE LAYER OF CELLS
All cells in direct contact with basement membrane
In areas where stress is minimal
Filtration, absorption, or secretion is primary function
E.g., lining of air sacs of lungs, intestines, blood vessels
Stratified epithelium
2+ layers of epithelial cells
Only basal layer in contact with basement membrane
In areas subjected to mechanical stress
Better able to resist wear and tear
Basal layer cells continuously regenerate (apical cells lost)
